Reservoir computing has been considered as a promising intelligent computing paradigm for effectively processing complex temporal information.Exploiting tunable and reproducible dynamics in the single electronic devic...Reservoir computing has been considered as a promising intelligent computing paradigm for effectively processing complex temporal information.Exploiting tunable and reproducible dynamics in the single electronic device have been desired to implement the “reservoir” and the “readout” layer of reservoir computing system.Two-dimensional moiré materials,with an artificial lattice constant many times larger than the atomic length scale,are one type of most studied artificial quantum materials in community of material science and condensed-matter physics over the past years.These materials are featured with gate-tunable periodic potential and electronic correlation,thus varying the electric field allows the electrons in the moiré potential per unit cell to exhibit distinct and reproducible dynamics,showing great promise in robust reservoir computing.Here,we report that a moiré synaptic transistor can be used to implement the reservoir computing system with a homogeneous reservoir-readout architecture.The synaptic transistor is fabricated based on an h-BN/bilayer graphene/h-BN moiré heterostructure,exhibiting ferroelectricity-like hysteretic gate voltage dependence of resistance.Varying the magnitude of the gate voltage enables the moiré transistor to switch between long-term memory and shortterm memory with nonlinear dynamics.By employing the short-and long-term memories as the reservoir nodes and weights of the readout layer,respectively,we construct a full-moiré physical neural network and demonstrate that the classification accuracy of 90.8% can be achieved for the MNIST(Modified National Institute of Standards and Technology) handwritten digits database.Our work would pave the way towards the development of neuromorphic computing based on moiré materials.展开更多
Hybrid materials constructed from a visible-light-absorbing semiconductor and a functional metal complex have attracted attention as efficient photocatalysts for CO_(2) reduction with high selectivity to a desired pro...Hybrid materials constructed from a visible-light-absorbing semiconductor and a functional metal complex have attracted attention as efficient photocatalysts for CO_(2) reduction with high selectivity to a desired product.In this work,defect fluorite-type Ln-Ta oxynitrides LnTaO_(x)N_(y)(Ln=Nd,Sm,Gd,Tb,Dy and Ho)were examined as the semiconductor component in a hybrid photocatalyst system combined with known Ag nanoparticle promoter and binuclear ruthenium(Ⅱ)complex(RuRu’).Among the LnTaO_(x)N_(y) examined,TbTaO_(x)N_(y) gave the highest performance for CO_(2) reduction under visible light(k>400 nm),with a Ru Ru0-based turnover number of 18 and high selectivity to formate(>99%).Physicochemical analyses indicated that high crystallinity and more negative conduction band potential of Ln Ta O_(x)N_(y)with the absence of Ln-4 f states in the band gap structure contributed to higher activity of the hybrid photocatalyst.展开更多
The effect of cold high pressure densification(CHPD)on anisotropy of the critical current density(Jc)in《in situ》single core binary and alloyed MgB2 tapes has been determined as a function of temperatures at 4.2 K,20...The effect of cold high pressure densification(CHPD)on anisotropy of the critical current density(Jc)in《in situ》single core binary and alloyed MgB2 tapes has been determined as a function of temperatures at 4.2 K,20 K and 25 K as well as at applied magnetic fields up to 19 T.The study includes binary and C4H6O5(malic acid)doped MgB2 tapes before and after CHPD.It is remarkable that the CHPD process not only improved the Jc values,in particular at the higher magnetic fields,but also decreased the anisotropy ratio,Г=JC^///JC^⊥In binary MgB2 tapes,the anisotropy factor F increases with higher aspect ratios,even after applying CHPD.In malic acid(C4H6O5)doped tapes,however,the application of CHPD leads only to small enhancements ofГ,even for higher aspect ratios.This is attributed to the higher carbon content in the MgB2 filaments,which in turn is a consequence of the reduced chemical reaction path in the densified filaments.At all applied field values,it was found that CHPD processed C4H6O5 doped tapes exhibit an almost isotropic behavior.This constitutes an advantage in view of industrial magnet applications using wires with square or slightly rectangular configuration.展开更多
A facile one-step method was developed for the fabrication of hierarchical ZnO film on substrate. Neither seed nor catalyst layer is necessary for the growth of hierarchical ZnO film. Three kinds of nucleation process...A facile one-step method was developed for the fabrication of hierarchical ZnO film on substrate. Neither seed nor catalyst layer is necessary for the growth of hierarchical ZnO film. Three kinds of nucleation process were found, and the influences of growth time, growth electrolyte, growth temperature on the morphology of ZnO film were evaluated. Hierarchical ZnO film can absorb more than 97% of incident photons with wavelength shorter than 380 nm. Such hierarchical ZnO film would be a promising scaffold for photoelectrochemical application.展开更多
Covalent modification of graphene oxide(GO)with functional chromophores plays an important role in constructing various kinds of advanced optoelectronic materials for applications in molecular diagnosis,light-harvesti...Covalent modification of graphene oxide(GO)with functional chromophores plays an important role in constructing various kinds of advanced optoelectronic materials for applications in molecular diagnosis,light-harvesting,photodynamic therapy,and optical limiting.Herein,a new approach to functionalizing GO with meso-substituted formylporphyrins at GO’s edge sites via imidazole condensation is developed,which affords a novel GO-imi-Por nanohybrid covalently-linked by imidazole rings between two components.The structure of the GO-imi-Por nanohybrid was thoroughly characterized by scanning electron microscopy(SEM),attenuated total reflectance-Fourier transform infrared(ATR-FTIR),Raman,and X-ray photoelectron spectroscopy(XPS).The red-shifted steady-state absorption,95%quenched fluorescence,and largely enhanced nonlinear optical(NLO)properties through Z-scan studies at lower input energies demonstrate that this GO-imi-Por nanohybrid exhibits a more effective photoinduced energy/electron transfer between the intrahybrid two components and can be flexibly applied as an optical limiter candidate.This covalent edge-functionalization approach provides a new paradigm for constructing various edge-expanding GO nanohybrids with an efficient energy/electron transfer process and improved nonlinear optical effects,which would draw inspiration for engineering more adaptable optoelectronic devices.展开更多
Monolayer group VI transition metal dichalcogenides(TMDs)have recently emerged as promising candidates for photonic and opto-valleytronic applications.The optoelectronic properties of these atomically-thin semiconduct...Monolayer group VI transition metal dichalcogenides(TMDs)have recently emerged as promising candidates for photonic and opto-valleytronic applications.The optoelectronic properties of these atomically-thin semiconducting crystals are strongly governed by the tightly bound electron-hole pairs such as excitons and trions(charged excitons).The anomalous spin and valley configurations at the conduction band edges in monolayer WS_(2)give rise to even more fascinating valley many-body complexes.Here we find that the indirect Q valley in the first Brillouin zone of monolayer WS_(2)plays a critical role in the formation of a new excitonic state,which has not been well studied.By employing a high-quality h-BN encapsulated WS_(2)field-effect transistor,we are able to switch the electron concentration within K-Q valleys at conduction band edges.Consequently,a distinct emission feature could be excited at the high electron doping region.Such feature has a competing population with the K valley trion,and experiences nonlinear power-law response and lifetime dynamics under doping.Our findings open up a new avenue for the study of valley many-body physics and quantum optics in semiconducting 2D materials,as well as provide a promising way of valley manipulation for next-generation entangled photonic devices.展开更多
Moiré superlattices have emerged as a highly controllable quantum platform for exploration of various fascinating phenomena,such as Mott insulator states,ferroelectric order,unconventional superconductivity and o...Moiré superlattices have emerged as a highly controllable quantum platform for exploration of various fascinating phenomena,such as Mott insulator states,ferroelectric order,unconventional superconductivity and orbital ferromagnetism.Although remarkable progress has been achieved,current research in moiré physics has mainly focused on the single species properties,while the coupling between distinct moiré quantum phenomena remains elusive.Here we demonstrate,for the first time,the strong coupling between ferroelectricity and correlated states in a twisted quadrilayer MoS2moiré superlattice,where the twist angles are controlled in sequence to be ~57°,~0°,and ~-57°.Correlated insulator states are unambiguously established at moiré band filling factors v = 1,2,3 of twisted quadrilayer MoS_(2).Remarkably,ferroelectric order can occur at correlated insulator states and disappears quickly as the moiré band filling deviates from the integer fillings,providing smoking gun evidences of the coupling between ferroelectricity and correlated states.Our results demonstrate the coupling between different moiré quantum properties and will hold great promise for new moiré physics and applications.展开更多
The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones o...The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones of FSW TWIP joint were studied for the first time.The results showed that the content of recrystallized grains in the stir zone(SZ)increased from 10.5%of basal material(BM)to 14.2%,and that of heat affected zone(HAZ)increased to 78.6%.The percentage of annealing twins decreased from 26.8%in BM to 11%in SZ,while increased to 35%in HAZ.Compared with the BM,the ultimate tensile strength and yield strength of the FSW joint increased to 1036 and 550 MPa,respectively,reaching 106.7%and 110.9%of BM,respectively.The elongation of the entire joint was 50.5%,which was lower than that of BM due to the nonuniform deformation during the tensile test.The engineering strain was mainly concentrated in BM and SZ and transferred to each other during the tensile test,while the engineering strain in HAZ was always the lowest.Finally,the tensile fracture occurred in the SZ.The order of ultimate tensile strength of micro-zones in the FSW joint was as follows:HAZ>BM≈SZ.The order of yield strength was as follows:HAZ>BM>SZ.展开更多
Due to its unique electronic structure and special size effect,two-dimensional(2D)nanomaterials have shown great potential far beyond bulk materials in the field of photocatalysis.How to deeply explore the photocataly...Due to its unique electronic structure and special size effect,two-dimensional(2D)nanomaterials have shown great potential far beyond bulk materials in the field of photocatalysis.How to deeply explore the photocatalytic mechanism of 2D nanomaterials and design more efficient 2D semiconductor photocatalysts are research hotspots.This review provides a comprehensive introduction to typical 2D nanomaterials and discusses their current application status in the field of photocatalysis.The effects of material properties such as band structure,morphology,crystal face structure,crystal structure and surface defects on the photocatalytic process are discussed.The main modification methods are highlighted,including doping,noble metal deposition,heterojunction,thickness adjustment,defect engineering,and dye sensitization in 2D material systems.Finally,the future development of 2D nanomaterials is prospected.It is hoped that this paper can provide systematic and useful information for researchers engaged in the field of photocatalysis.展开更多
A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long peri...A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.展开更多
Recent developments in the use of diamond materials as metal-oxide-semiconductor field-effect transistors (MOSFETs) are in- troduced in this article, including an analysis of the advantages of the device owing to the ...Recent developments in the use of diamond materials as metal-oxide-semiconductor field-effect transistors (MOSFETs) are in- troduced in this article, including an analysis of the advantages of the device owing to the unique physical properties of diamond materials, such as their high-temperature and negative electron affinity characteristics. Recent research progress by domestic and international research groups on performance improvement of hydrogen-terminated and oxygen-terminated diamond-based MOSFETs is also summarized. Currently, preparation of large-scale diamond epitaxial layers is still relatively difficult, and improvements and innovations in the device structure are still ongoing. However, the key to improving the performance of diamond-based MOSFET devices lies in improving the mobility of channel carriers. This mainly includes improvements in doping technologies and reductions in interface state density or carrier traps. These will be vital research goals for the future of diamond-based MOSFETs.展开更多
Axially coordinated metal-porphyrin-functionalized multi-walled carbon nanotube (MWCNT) nanohybrids were prepared via two different synthetic approaches (a one-pot 1,3-dipolar cycloaddition reaction and a stepwise ...Axially coordinated metal-porphyrin-functionalized multi-walled carbon nanotube (MWCNT) nanohybrids were prepared via two different synthetic approaches (a one-pot 1,3-dipolar cycloaddition reaction and a stepwise approach that involved 1,3-dipolar cycloaddition followed by nucleophilic substitution), and characterized through spectroscopic techniques. Attachment of the tin porphyrins to the surface of the MWCNTs significantly improves their solubility and ease of processing. These axially coordinated (5,10,15,20-tetraphenylporphyrinato)tin(Ⅳ) (SnTPP)- MWCNTs exhibit significant fluorescence quenching. The third-order nonlinear optical properties of the resultant nanohybrids were studied by using the Z-scan technique at 532 nm with both nanosecond and picosecond laser pulses. The results show that the nanohybrids exhibit significant reverse saturable absorption or saturable absorption when nanosecond or picosecond pulses, respectively, are employed. Improvement in the nanosecond regime nonlinear absorption is observed on proceeding to the nanohybrids and is ascribed to a combination of the outstanding properties of MWCNTs and the chemically attached metal-porphyrins.展开更多
Alum has an excellent safety record and is the only licensed inorganic adjuvant for human vaccines.However,the exploration of alum nanosheets as chemotherapy drug delivery system,especially the clarification about the...Alum has an excellent safety record and is the only licensed inorganic adjuvant for human vaccines.However,the exploration of alum nanosheets as chemotherapy drug delivery system,especially the clarification about the relationship between structures and drug loading properties,is totally insufficient.Herein,aluminum hydroxides(AlOOH)nanosheets with tunable specific surface area and pore size were synthesized by adjusting the synthesis time in the presence of triblock copolymers.The obtained materials exhibited the highest surface area about 470 m2/g.The structure-dependent chemotherapy drug loading capability for AlOOH nanosheets was observed:the higher specific surface area and pore size are,the higher amount of chemotherapy drug is loaded.AlOOH nanosheets loaded with doxorubicin showed a pH-dependent sustained release behavior with quick release in low pH about 5 and slow release in pH around 7.4.Doxorubicin-loaded AlOOH nanosheets exhibited much higher cancer cellular uptake efficiency than that in free form by flow cytometry.Moreover,doxorubicin-loaded AlOOH nanosheets with high specific surface area showed an increased cellular uptake efficiency and enhanced ratios of apoptosis and necrosis,compared with those showing low specific surface area.Therefore,AlOOH nanosheets are promising materials as chemotherapy drug delivery system.展开更多
Molybdenum phosphide (MoP) flakes were synthesized by the reduction of hexaammonium heptamolybdate tetrahydrate and ammonium dihydrogen phosphate. The flakes are porous and constructed by MoP nanoparticles with ca. 10...Molybdenum phosphide (MoP) flakes were synthesized by the reduction of hexaammonium heptamolybdate tetrahydrate and ammonium dihydrogen phosphate. The flakes are porous and constructed by MoP nanoparticles with ca. 100 nm diameters. The lateral size of flakes ranges from less than 1 μm to larger than 5 μm, and the thickness of MoP fakes is ca. 200 nm. The mixture of MoP flakes and carbon black exhibits effective catalytic activity in the hydrogen evolution reaction. The optimal overpotential required for 20 mA·cm﹣2 current density is 155 mV in acidic solution and 184 mV in basic solution. The mixture can work stably in long-term hydrogen generation in both acidic and basic solution. The faradaic yield of mixture in hydrogen evolution reaction is nearly 100% in both acidic and basic solution. The Mo and P species in MoP flakes are found to have small positive and negative charge, respectively. The catalytic activity of MoP flakes is likely to be correlated with this charged nature.展开更多
Twisting two layers into a magic angle(MA) of ~1.1°is found essential to create low energy flat bands and the resulting correlated insulating,superconducting,and magnetic phases in twisted bilayer graphene(TBG).W...Twisting two layers into a magic angle(MA) of ~1.1°is found essential to create low energy flat bands and the resulting correlated insulating,superconducting,and magnetic phases in twisted bilayer graphene(TBG).While most of previous works focus on revealing these emergent states in MA-TBG,a study of the twist angle dependence,which helps to map an evolution of these phases,is yet less explored.Here,we report a magnetotransport study on one non-magic angle TBG device,whose twist angle θ changes from 1.25° at one end to 1.43°at the other.For θ=1.25° we observe an emergence of topological insulating states at hole side with a sequence of Chern number |C|=4-|v|,where v is the number of electrons(holes) in moire unite cell.When θ> 1.25°,the Chern insulator from flat band disappears and evolves into fractal Hofstadter butterfly quantum Hall insulator where magnetic flux in one moire unite cell matters.Our observations will stimulate further theoretical and experimental investigations on the relationship between electron interactions and non-trivial band topology.展开更多
Metal oxide and carbide strengthening molybdenum(Mo)alloys have been designed as promising ad-vanced materials in refractory metals to solve some of the core engineering problems in superalloy ap-plications.Hence,ther...Metal oxide and carbide strengthening molybdenum(Mo)alloys have been designed as promising ad-vanced materials in refractory metals to solve some of the core engineering problems in superalloy ap-plications.Hence,there is a need to summarize the results obtained and evaluate the opportunities for preparing high-performance Mo alloys by strengthening metal oxides and carbides to improve the per-formance characteristics of Mo metal materials.This paper reviews the results of the reported work con-cerning the structure and properties of Mo alloys with different metal oxide and carbide strengthening methods added to Mo matrix.The influence of the doping of La 2 O 3 and Y 2 O 3 particles,ceramic Al 2 O 3 and ZrO 2 particles,and refractory TiC and ZrC carbides particles of Mo alloys are discussed.The impacts of particle morphology,size,distribution and volume fractions of oxide and carbide are analyzed,as well as the specific features of different doping techniques for obtaining high-performance Mo alloys mate-rials.This work will guide future research on the design of high-performance refractory Mo alloys by adding oxides and carbide particles,helping to solve the core issues in the field of superalloy application research.展开更多
Low-carbon steel plates were successfully subjected to normal friction stir processing(NFSP) in air and submerged friction stir processing(SFSP) under water, and the microstructure, mechanical properties, and corrosio...Low-carbon steel plates were successfully subjected to normal friction stir processing(NFSP) in air and submerged friction stir processing(SFSP) under water, and the microstructure, mechanical properties, and corrosion behavior of the NFSP and SFSP samples were investigated. Phase transformation and dynamic recrystallization resulted in fine-grained ferrite and martensite in the processed zone. The SFSP samples had smaller ferrites(5.1 μm), finer martensite laths(557 nm), and more uniform distribution of martensite compared to the NFSP samples. Compared to the base material(BM), the microhardness of the NFSP and SFSP samples increased by 19.8% and 27.1%, respectively because of the combined strengthening effects of grain refinement, phase transformation, and dislocation. The ultimate tensile strengths(UTSs) of the NFSP and SFSP samples increased by 27.1% and 38.7%, respectively. Grain refinement and martensite transformation also improved the electrochemical corrosion properties of the low-carbon steel. Overall, the SFSP samples had better mechanical properties and electrochemical corrosion resistance than the NFSP samples.展开更多
A highly efficient and stable hydrotalcite-derived Cu-MgAlO catalyst was developed for the partial oxidation of cyclohexane with molecular oxygen.The physical–chemical properties of Cu-MgAlO catalysts were studied,an...A highly efficient and stable hydrotalcite-derived Cu-MgAlO catalyst was developed for the partial oxidation of cyclohexane with molecular oxygen.The physical–chemical properties of Cu-MgAlO catalysts were studied,and the results indicated that the copper component had been successfully introduced into the hydrotalcite unit layer structure.The catalytic reaction results showed that copper as the active species could activate CAH bond and effectively promote the decomposition of cyclohexyl hydroperoxide(CHHP)to the mixture of cyclohexanol and cyclohexanone(KA oil).8.3%of cyclohexane conversion and 82.9%of selectivity for KA oil were obtained over 9%Cu-MgAlO catalyst at 150℃with 0.6 MPa of oxygen pressure for 2 h.Especially,its catalytic performance was still stable after five runs.展开更多
Magnetoresistance(MR) provides rich information about Fermi surface, carrier scatterings, and exotic phases for a given electronic system. Here, we report a study of the magnetoresistance for the metallic states in tw...Magnetoresistance(MR) provides rich information about Fermi surface, carrier scatterings, and exotic phases for a given electronic system. Here, we report a study of the magnetoresistance for the metallic states in twisted double bilayer graphene(TDBG). We observe quadratic magnetoresistance in both Moiré valence band(VB) and Moiré conduction band(CB). The scaling analysis shows validity of Kohler's rule in the Moiré valence band. On the other hand, the quadratic magnetoresistance appears near the halo structure in the Moiré conduction band, and it violates Kohler's rule, demonstrating the MR scaling related to band structure in TDBG. We also propose an alternative scaling near the halo structure. Further analysis implies that the observed quadratic magnetoresistance and alternative scaling in conduction band are related to the halo boundary. Our results may inspire investigation on MR in twisted 2D materials and provide new knowledge for MR study in condensed matter physics.展开更多
Transition metal dichalcogenides(TMDs),being valley selectively,are an ideal system hosting excitons.Stacking TMDs together to form heterostructure offers an exciting platform to engineer new optical and electronic pr...Transition metal dichalcogenides(TMDs),being valley selectively,are an ideal system hosting excitons.Stacking TMDs together to form heterostructure offers an exciting platform to engineer new optical and electronic properties in solid-state systems.However,due to the limited accuracy and repetitiveness of sample preparation,the effects of interlayer coupling on the electronic and excitonic properties have not been systematically investigated.In this report,we study the photoluminescence spectra of bilayer-bilayer MoS_(2)/WS_(2) heterostructure with a typeⅡband alignment.We demonstrate that thermal annealing can increase interlayer coupling in the van der Waals heterostructures,and after thermally induced band hybridization such heterostructure behaves more like an artificial new solid,rather than just the combination of two individual TMD components.We also carry out experimental and theoretical studies of the electric controllable direct and indirect infrared interlayer excitons in such system.Our study reveals the impact of interlayer coupling on interlayer excitons and will shed light on the understanding and engineering of layer-controlled spin-valley configuration in twisted van der Waals heterostructures.展开更多
基金supported in part by the National Natural Science Foundation of China(Grant Nos.62122036,12322407,62034004,61921005,12074176,and 61974176)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB44000000)+1 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.020414380203 and 020414380179)the support from the AIQ foundation。
文摘Reservoir computing has been considered as a promising intelligent computing paradigm for effectively processing complex temporal information.Exploiting tunable and reproducible dynamics in the single electronic device have been desired to implement the “reservoir” and the “readout” layer of reservoir computing system.Two-dimensional moiré materials,with an artificial lattice constant many times larger than the atomic length scale,are one type of most studied artificial quantum materials in community of material science and condensed-matter physics over the past years.These materials are featured with gate-tunable periodic potential and electronic correlation,thus varying the electric field allows the electrons in the moiré potential per unit cell to exhibit distinct and reproducible dynamics,showing great promise in robust reservoir computing.Here,we report that a moiré synaptic transistor can be used to implement the reservoir computing system with a homogeneous reservoir-readout architecture.The synaptic transistor is fabricated based on an h-BN/bilayer graphene/h-BN moiré heterostructure,exhibiting ferroelectricity-like hysteretic gate voltage dependence of resistance.Varying the magnitude of the gate voltage enables the moiré transistor to switch between long-term memory and shortterm memory with nonlinear dynamics.By employing the short-and long-term memories as the reservoir nodes and weights of the readout layer,respectively,we construct a full-moiré physical neural network and demonstrate that the classification accuracy of 90.8% can be achieved for the MNIST(Modified National Institute of Standards and Technology) handwritten digits database.Our work would pave the way towards the development of neuromorphic computing based on moiré materials.
基金supported by a Grant-in-Aid for Scientific Research on Innovative Area “Mixed Anion(Projects JP16K21724 and JP16H06441)”from the Japan Society for the Promotion of Science(JSPS)a CREST program(Project JPMJCR13L1)from the Japan Science and Technology Agency(JST)a JSPS Fellowship for Young Scientists(Project JP17J06914)。
文摘Hybrid materials constructed from a visible-light-absorbing semiconductor and a functional metal complex have attracted attention as efficient photocatalysts for CO_(2) reduction with high selectivity to a desired product.In this work,defect fluorite-type Ln-Ta oxynitrides LnTaO_(x)N_(y)(Ln=Nd,Sm,Gd,Tb,Dy and Ho)were examined as the semiconductor component in a hybrid photocatalyst system combined with known Ag nanoparticle promoter and binuclear ruthenium(Ⅱ)complex(RuRu’).Among the LnTaO_(x)N_(y) examined,TbTaO_(x)N_(y) gave the highest performance for CO_(2) reduction under visible light(k>400 nm),with a Ru Ru0-based turnover number of 18 and high selectivity to formate(>99%).Physicochemical analyses indicated that high crystallinity and more negative conduction band potential of Ln Ta O_(x)N_(y)with the absence of Ln-4 f states in the band gap structure contributed to higher activity of the hybrid photocatalyst.
基金This work was supported by the Australian Research Council(Grant No.LP160101784)A.K.thanks the Researchers Supporting Project(RSP-2019/127)King Saud University,Riyadh,Saudi Arabia for the support.This work was performed in part at the Queensland node of the Australian National Fabrication Facility,a company established under the National Collaborative Research Infrastructure Strategy to provide nano-and microfabrication facilities for Australia's researchers.M.M.acknowledges an internal funding project of the University of Osijek(ZUP-2018).
文摘The effect of cold high pressure densification(CHPD)on anisotropy of the critical current density(Jc)in《in situ》single core binary and alloyed MgB2 tapes has been determined as a function of temperatures at 4.2 K,20 K and 25 K as well as at applied magnetic fields up to 19 T.The study includes binary and C4H6O5(malic acid)doped MgB2 tapes before and after CHPD.It is remarkable that the CHPD process not only improved the Jc values,in particular at the higher magnetic fields,but also decreased the anisotropy ratio,Г=JC^///JC^⊥In binary MgB2 tapes,the anisotropy factor F increases with higher aspect ratios,even after applying CHPD.In malic acid(C4H6O5)doped tapes,however,the application of CHPD leads only to small enhancements ofГ,even for higher aspect ratios.This is attributed to the higher carbon content in the MgB2 filaments,which in turn is a consequence of the reduced chemical reaction path in the densified filaments.At all applied field values,it was found that CHPD processed C4H6O5 doped tapes exhibit an almost isotropic behavior.This constitutes an advantage in view of industrial magnet applications using wires with square or slightly rectangular configuration.
文摘A facile one-step method was developed for the fabrication of hierarchical ZnO film on substrate. Neither seed nor catalyst layer is necessary for the growth of hierarchical ZnO film. Three kinds of nucleation process were found, and the influences of growth time, growth electrolyte, growth temperature on the morphology of ZnO film were evaluated. Hierarchical ZnO film can absorb more than 97% of incident photons with wavelength shorter than 380 nm. Such hierarchical ZnO film would be a promising scaffold for photoelectrochemical application.
文摘Covalent modification of graphene oxide(GO)with functional chromophores plays an important role in constructing various kinds of advanced optoelectronic materials for applications in molecular diagnosis,light-harvesting,photodynamic therapy,and optical limiting.Herein,a new approach to functionalizing GO with meso-substituted formylporphyrins at GO’s edge sites via imidazole condensation is developed,which affords a novel GO-imi-Por nanohybrid covalently-linked by imidazole rings between two components.The structure of the GO-imi-Por nanohybrid was thoroughly characterized by scanning electron microscopy(SEM),attenuated total reflectance-Fourier transform infrared(ATR-FTIR),Raman,and X-ray photoelectron spectroscopy(XPS).The red-shifted steady-state absorption,95%quenched fluorescence,and largely enhanced nonlinear optical(NLO)properties through Z-scan studies at lower input energies demonstrate that this GO-imi-Por nanohybrid exhibits a more effective photoinduced energy/electron transfer between the intrahybrid two components and can be flexibly applied as an optical limiter candidate.This covalent edge-functionalization approach provides a new paradigm for constructing various edge-expanding GO nanohybrids with an efficient energy/electron transfer process and improved nonlinear optical effects,which would draw inspiration for engineering more adaptable optoelectronic devices.
基金the strong support from Singapore Ministry of Education via AcRF Tier 3 Programme “Geometrical Quantum Materials” (MOE2018-T3-1-002)AcRF Tier 2 grants (MOE2017-T2-1040)+7 种基金the National Natural Science Foundation of China (Grant No. 61435010)the National Natural Science Foundation of China (Grant No. 61905156)the National Natural Science Foundation of China (Grant No. 61575010)the China Postdoctoral Science Foundation (Grant No. 2017M622764)the Natural Science Foundation of Fujian Province (Grant No. 2022J01555)the Beijing Municipal Natural Science Foundation (Grant No. 4162016)the financial support of the Presidential Postdoctoral Fellowship program of the Nanyang Technological Universitysupport from the Elemental Strategy Initiative conducted by the MEXT, Japan and the CREST (JPMJCR15F3), JST
文摘Monolayer group VI transition metal dichalcogenides(TMDs)have recently emerged as promising candidates for photonic and opto-valleytronic applications.The optoelectronic properties of these atomically-thin semiconducting crystals are strongly governed by the tightly bound electron-hole pairs such as excitons and trions(charged excitons).The anomalous spin and valley configurations at the conduction band edges in monolayer WS_(2)give rise to even more fascinating valley many-body complexes.Here we find that the indirect Q valley in the first Brillouin zone of monolayer WS_(2)plays a critical role in the formation of a new excitonic state,which has not been well studied.By employing a high-quality h-BN encapsulated WS_(2)field-effect transistor,we are able to switch the electron concentration within K-Q valleys at conduction band edges.Consequently,a distinct emission feature could be excited at the high electron doping region.Such feature has a competing population with the K valley trion,and experiences nonlinear power-law response and lifetime dynamics under doping.Our findings open up a new avenue for the study of valley many-body physics and quantum optics in semiconducting 2D materials,as well as provide a promising way of valley manipulation for next-generation entangled photonic devices.
基金supported by the Key-Area Research and Development Program of Guangdong Province,China (Grant No.2020B0101340001)the National Key Research and Development Program of China (Grant Nos.2021YFA1202900 and 2020YFA0309600)+4 种基金the National Science Foundation of China (Grant Nos.61888102,11834017,1207441,and 12274447)the Strategic Priority Research Program of CAS(Grant Nos.XDB30000000 and XDB33000000)the supports from the Elemental Strategy Initiative conducted by the MEXT,Japan(Grant No.JPMXP0112101001)JSPS KAKENHI(Grant Nos.19H05790,20H00354,and 21H05233)A3 Foresight by JSPS。
文摘Moiré superlattices have emerged as a highly controllable quantum platform for exploration of various fascinating phenomena,such as Mott insulator states,ferroelectric order,unconventional superconductivity and orbital ferromagnetism.Although remarkable progress has been achieved,current research in moiré physics has mainly focused on the single species properties,while the coupling between distinct moiré quantum phenomena remains elusive.Here we demonstrate,for the first time,the strong coupling between ferroelectricity and correlated states in a twisted quadrilayer MoS2moiré superlattice,where the twist angles are controlled in sequence to be ~57°,~0°,and ~-57°.Correlated insulator states are unambiguously established at moiré band filling factors v = 1,2,3 of twisted quadrilayer MoS_(2).Remarkably,ferroelectric order can occur at correlated insulator states and disappears quickly as the moiré band filling deviates from the integer fillings,providing smoking gun evidences of the coupling between ferroelectricity and correlated states.Our results demonstrate the coupling between different moiré quantum properties and will hold great promise for new moiré physics and applications.
基金the National Natural Science Foundation of China(Nos.52034005,52227807,52104383,and 51974220)China’s National Defense Science and Technology(173 Program)(No.2021-JCJQ-JJ-0190)+2 种基金the Shaanxi Province National Science Fund for Distinguished Young Schol-ars(No.2022JC-24)the Key Research and Development Pro-gram of Shaanxi Province(No.2020ZDLGY13-06)the Scientific Re-search Program for Youth Innovation Team Construction of Shaanxi Provincial Department of Education(No.21JP058)。
文摘The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones of FSW TWIP joint were studied for the first time.The results showed that the content of recrystallized grains in the stir zone(SZ)increased from 10.5%of basal material(BM)to 14.2%,and that of heat affected zone(HAZ)increased to 78.6%.The percentage of annealing twins decreased from 26.8%in BM to 11%in SZ,while increased to 35%in HAZ.Compared with the BM,the ultimate tensile strength and yield strength of the FSW joint increased to 1036 and 550 MPa,respectively,reaching 106.7%and 110.9%of BM,respectively.The elongation of the entire joint was 50.5%,which was lower than that of BM due to the nonuniform deformation during the tensile test.The engineering strain was mainly concentrated in BM and SZ and transferred to each other during the tensile test,while the engineering strain in HAZ was always the lowest.Finally,the tensile fracture occurred in the SZ.The order of ultimate tensile strength of micro-zones in the FSW joint was as follows:HAZ>BM≈SZ.The order of yield strength was as follows:HAZ>BM>SZ.
基金supported by the National Natural Science Foundation of China Youth Program (52204399)the Postdoctoral Research Foundation of China (2021MD703866)+6 种基金the Scientific and Technological Innovation Team Project of Shaanxi Innovation Capability Support Plan (2022TD-30)Youth Innovation Team of Shaanxi Universities (2019-2022)Fok Ying Tung Education Foundation (171101)Natural Science Basic Research Program of Shaanxi Province (2022JQ-478)the Scientific Research Program of Youth Innovation Team of Shaanxi (22JP037)the Science and Technology Project of Universities and Institutes StaffServing Enterprises in Xi'an (22GXFW0059)Top Young Talents Project of“Special Support Program for High Level Talents”in Shaanxi Province (2018-2023)。
文摘Due to its unique electronic structure and special size effect,two-dimensional(2D)nanomaterials have shown great potential far beyond bulk materials in the field of photocatalysis.How to deeply explore the photocatalytic mechanism of 2D nanomaterials and design more efficient 2D semiconductor photocatalysts are research hotspots.This review provides a comprehensive introduction to typical 2D nanomaterials and discusses their current application status in the field of photocatalysis.The effects of material properties such as band structure,morphology,crystal face structure,crystal structure and surface defects on the photocatalytic process are discussed.The main modification methods are highlighted,including doping,noble metal deposition,heterojunction,thickness adjustment,defect engineering,and dye sensitization in 2D material systems.Finally,the future development of 2D nanomaterials is prospected.It is hoped that this paper can provide systematic and useful information for researchers engaged in the field of photocatalysis.
基金supported by the National Key Research and Development Program of China(2021YFB3501002)State Key Program of National Natural Science Foundation of China(5203405)+3 种基金National Natural Science Foundation of China(51974220,52104383)National Key Research and Development Program of China(2021YFB3700902)Key Research and Development Program of Shaanxi Province(2020ZDLGY13-06,2017ZDXM-GY-037)Shaanxi Province National Science Fund for Distinguished Young Scholars(2022JC-24)。
文摘A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.
基金financially supported by the National Key Research and Development Program of China (No.2018YFB0406501)the Beijing Municipal Science and Technology Commission (No. Z181100004418009)the National Natural Science Foundation of China (No.51702313)
文摘Recent developments in the use of diamond materials as metal-oxide-semiconductor field-effect transistors (MOSFETs) are in- troduced in this article, including an analysis of the advantages of the device owing to the unique physical properties of diamond materials, such as their high-temperature and negative electron affinity characteristics. Recent research progress by domestic and international research groups on performance improvement of hydrogen-terminated and oxygen-terminated diamond-based MOSFETs is also summarized. Currently, preparation of large-scale diamond epitaxial layers is still relatively difficult, and improvements and innovations in the device structure are still ongoing. However, the key to improving the performance of diamond-based MOSFET devices lies in improving the mobility of channel carriers. This mainly includes improvements in doping technologies and reductions in interface state density or carrier traps. These will be vital research goals for the future of diamond-based MOSFETs.
基金Financial support from the National Natural Science Foundation of China (Nos. 51432006, 50925207, and 51172100), the Ministry of Science and Technology of China for the International Science Linkages Program (No. 2011DFG52970), the Ministry of Education of China for the Changjiang Innovation Research Team (No. IRT14R23), the Ministry of Education and the State Administration of Foreign Experts Affairs for the 111 Project (No. B13025), 100 Talents Program of CAS, and Jiangsu Innovation Research Team are gratefully acknowledged. M. G. H., M. P. C., and C. Z. thank the Australian Research Council (ARC) for support.
文摘Axially coordinated metal-porphyrin-functionalized multi-walled carbon nanotube (MWCNT) nanohybrids were prepared via two different synthetic approaches (a one-pot 1,3-dipolar cycloaddition reaction and a stepwise approach that involved 1,3-dipolar cycloaddition followed by nucleophilic substitution), and characterized through spectroscopic techniques. Attachment of the tin porphyrins to the surface of the MWCNTs significantly improves their solubility and ease of processing. These axially coordinated (5,10,15,20-tetraphenylporphyrinato)tin(Ⅳ) (SnTPP)- MWCNTs exhibit significant fluorescence quenching. The third-order nonlinear optical properties of the resultant nanohybrids were studied by using the Z-scan technique at 532 nm with both nanosecond and picosecond laser pulses. The results show that the nanohybrids exhibit significant reverse saturable absorption or saturable absorption when nanosecond or picosecond pulses, respectively, are employed. Improvement in the nanosecond regime nonlinear absorption is observed on proceeding to the nanohybrids and is ascribed to a combination of the outstanding properties of MWCNTs and the chemically attached metal-porphyrins.
基金National Institute for Materials Science of Japan
文摘Alum has an excellent safety record and is the only licensed inorganic adjuvant for human vaccines.However,the exploration of alum nanosheets as chemotherapy drug delivery system,especially the clarification about the relationship between structures and drug loading properties,is totally insufficient.Herein,aluminum hydroxides(AlOOH)nanosheets with tunable specific surface area and pore size were synthesized by adjusting the synthesis time in the presence of triblock copolymers.The obtained materials exhibited the highest surface area about 470 m2/g.The structure-dependent chemotherapy drug loading capability for AlOOH nanosheets was observed:the higher specific surface area and pore size are,the higher amount of chemotherapy drug is loaded.AlOOH nanosheets loaded with doxorubicin showed a pH-dependent sustained release behavior with quick release in low pH about 5 and slow release in pH around 7.4.Doxorubicin-loaded AlOOH nanosheets exhibited much higher cancer cellular uptake efficiency than that in free form by flow cytometry.Moreover,doxorubicin-loaded AlOOH nanosheets with high specific surface area showed an increased cellular uptake efficiency and enhanced ratios of apoptosis and necrosis,compared with those showing low specific surface area.Therefore,AlOOH nanosheets are promising materials as chemotherapy drug delivery system.
文摘Molybdenum phosphide (MoP) flakes were synthesized by the reduction of hexaammonium heptamolybdate tetrahydrate and ammonium dihydrogen phosphate. The flakes are porous and constructed by MoP nanoparticles with ca. 100 nm diameters. The lateral size of flakes ranges from less than 1 μm to larger than 5 μm, and the thickness of MoP fakes is ca. 200 nm. The mixture of MoP flakes and carbon black exhibits effective catalytic activity in the hydrogen evolution reaction. The optimal overpotential required for 20 mA·cm﹣2 current density is 155 mV in acidic solution and 184 mV in basic solution. The mixture can work stably in long-term hydrogen generation in both acidic and basic solution. The faradaic yield of mixture in hydrogen evolution reaction is nearly 100% in both acidic and basic solution. The Mo and P species in MoP flakes are found to have small positive and negative charge, respectively. The catalytic activity of MoP flakes is likely to be correlated with this charged nature.
基金National Key R&D program(Grant No.2020YFA0309604)the National Natural Science Foundation of China(Grant Nos.61888102,11834017,and 12074413)+7 种基金the Strategic Priority Research Program of CAS(Grant Nos.XDB30000000 and XDB33000000)the Key-Area Research and Development Program of Guangdong Province(Grant No.2020B0101340001)Research Program of Beijing Academy of Quantum Information Sciences(Grant No.Y18G11)the start-up grant of ShanghaiTech UniversityNational Key R&D Program(Grant No.2020YFA0309601)Elemental Strategy Initiative conducted by the MEXT,Japan(Grant No.JPMXP0112101001)JSPS KAKENHI(Grant No.JP20H00354)CREST(JPMJCR15F3),JST。
文摘Twisting two layers into a magic angle(MA) of ~1.1°is found essential to create low energy flat bands and the resulting correlated insulating,superconducting,and magnetic phases in twisted bilayer graphene(TBG).While most of previous works focus on revealing these emergent states in MA-TBG,a study of the twist angle dependence,which helps to map an evolution of these phases,is yet less explored.Here,we report a magnetotransport study on one non-magic angle TBG device,whose twist angle θ changes from 1.25° at one end to 1.43°at the other.For θ=1.25° we observe an emergence of topological insulating states at hole side with a sequence of Chern number |C|=4-|v|,where v is the number of electrons(holes) in moire unite cell.When θ> 1.25°,the Chern insulator from flat band disappears and evolves into fractal Hofstadter butterfly quantum Hall insulator where magnetic flux in one moire unite cell matters.Our observations will stimulate further theoretical and experimental investigations on the relationship between electron interactions and non-trivial band topology.
基金the Outstanding Doctorate Dis-sertation Cultivation Fund of Xi’an University of Architecture and Technology(No.160842012)ScientificandTechnologicalInnova-tion Team Project of the Shaanxi Innovation Capability Support Plan,China(No.2022TD-30)+8 种基金the Fok Ying Tung Education Foun-dation(No.171101)Youth Innovation Team of Shaanxi Universi-ties(No.2019-2022)Top young talents project of“Special support program for high-level talents”in the Shaanxi Province(No.2018-2023)Major scientific and technological projects in the Shaanxi Province of China(No.2020ZDZX04-02-01)Service local spe-cial program of education department of Shaanxi province,China(No.21JC016)General Special Scientific Research Program of the Shaanxi Provincial Department of Education(No.21JK0722)the General Projects of Key R&D Program of the Shaanxi Province,China(No.2021GY-209)China Postdoctoral Science Foundation(No.2021M693878)China Postdoctoral Science Foundation(No.2021MD703866).
文摘Metal oxide and carbide strengthening molybdenum(Mo)alloys have been designed as promising ad-vanced materials in refractory metals to solve some of the core engineering problems in superalloy ap-plications.Hence,there is a need to summarize the results obtained and evaluate the opportunities for preparing high-performance Mo alloys by strengthening metal oxides and carbides to improve the per-formance characteristics of Mo metal materials.This paper reviews the results of the reported work con-cerning the structure and properties of Mo alloys with different metal oxide and carbide strengthening methods added to Mo matrix.The influence of the doping of La 2 O 3 and Y 2 O 3 particles,ceramic Al 2 O 3 and ZrO 2 particles,and refractory TiC and ZrC carbides particles of Mo alloys are discussed.The impacts of particle morphology,size,distribution and volume fractions of oxide and carbide are analyzed,as well as the specific features of different doping techniques for obtaining high-performance Mo alloys mate-rials.This work will guide future research on the design of high-performance refractory Mo alloys by adding oxides and carbide particles,helping to solve the core issues in the field of superalloy application research.
基金financially supported by the National Natural Science Foundation of China (Nos. U1360105, U1760201, and 51574192)
文摘Low-carbon steel plates were successfully subjected to normal friction stir processing(NFSP) in air and submerged friction stir processing(SFSP) under water, and the microstructure, mechanical properties, and corrosion behavior of the NFSP and SFSP samples were investigated. Phase transformation and dynamic recrystallization resulted in fine-grained ferrite and martensite in the processed zone. The SFSP samples had smaller ferrites(5.1 μm), finer martensite laths(557 nm), and more uniform distribution of martensite compared to the NFSP samples. Compared to the base material(BM), the microhardness of the NFSP and SFSP samples increased by 19.8% and 27.1%, respectively because of the combined strengthening effects of grain refinement, phase transformation, and dislocation. The ultimate tensile strengths(UTSs) of the NFSP and SFSP samples increased by 27.1% and 38.7%, respectively. Grain refinement and martensite transformation also improved the electrochemical corrosion properties of the low-carbon steel. Overall, the SFSP samples had better mechanical properties and electrochemical corrosion resistance than the NFSP samples.
基金the financial support by the National Natural Science Foundation of China (21676226 and 21776067)Natural Science Foundation for Distinguished Young Scholars in Hunan Province (2018JJ1023 and 2020JJ2014)+3 种基金Natural Science Foundation in Hunan Province (2018JJ3144)Key Research and Development Program in Hunan Province (2019GK2041)Scientific Research Fund of Hunan Provincial Education Department (17C0630)PhD Startup Foundation of Hunan University of Science and Technology (E51756)
文摘A highly efficient and stable hydrotalcite-derived Cu-MgAlO catalyst was developed for the partial oxidation of cyclohexane with molecular oxygen.The physical–chemical properties of Cu-MgAlO catalysts were studied,and the results indicated that the copper component had been successfully introduced into the hydrotalcite unit layer structure.The catalytic reaction results showed that copper as the active species could activate CAH bond and effectively promote the decomposition of cyclohexyl hydroperoxide(CHHP)to the mixture of cyclohexanol and cyclohexanone(KA oil).8.3%of cyclohexane conversion and 82.9%of selectivity for KA oil were obtained over 9%Cu-MgAlO catalyst at 150℃with 0.6 MPa of oxygen pressure for 2 h.Especially,its catalytic performance was still stable after five runs.
基金supported by the National Key Research and Development Program of China (Grant No. 2020YFA0309600)the National Natural Science Foundation of China (Grant Nos. 61888102, 11834017, and 12074413)+3 种基金the Strategic Priority Research Program of CAS (Grant Nos. XDB30000000 and XDB33000000)the Key-Area Research and Development Program of Guangdong Province (Grant No. 2020B0101340001)supported by the Elemental Strategy Initiative conducted by the MEXT, Japan, Grant Number JPMXP0112101001, JSPS KAKENHI (Grant No. JP20H00354)A3 Foresight by JSPS。
文摘Magnetoresistance(MR) provides rich information about Fermi surface, carrier scatterings, and exotic phases for a given electronic system. Here, we report a study of the magnetoresistance for the metallic states in twisted double bilayer graphene(TDBG). We observe quadratic magnetoresistance in both Moiré valence band(VB) and Moiré conduction band(CB). The scaling analysis shows validity of Kohler's rule in the Moiré valence band. On the other hand, the quadratic magnetoresistance appears near the halo structure in the Moiré conduction band, and it violates Kohler's rule, demonstrating the MR scaling related to band structure in TDBG. We also propose an alternative scaling near the halo structure. Further analysis implies that the observed quadratic magnetoresistance and alternative scaling in conduction band are related to the halo boundary. Our results may inspire investigation on MR in twisted 2D materials and provide new knowledge for MR study in condensed matter physics.
基金the National Key Research and Development Program of China(Grant No.2020YFA0309604)the National Natural Science Foundation of China(Grant Nos.11834017,61888102,and 12074413)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB30000000 and XDB33000000)the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2020B0101340001)the Research Program of Beijing Academy of Quantum Information Sciences(Grant No.Y18G11).
文摘Transition metal dichalcogenides(TMDs),being valley selectively,are an ideal system hosting excitons.Stacking TMDs together to form heterostructure offers an exciting platform to engineer new optical and electronic properties in solid-state systems.However,due to the limited accuracy and repetitiveness of sample preparation,the effects of interlayer coupling on the electronic and excitonic properties have not been systematically investigated.In this report,we study the photoluminescence spectra of bilayer-bilayer MoS_(2)/WS_(2) heterostructure with a typeⅡband alignment.We demonstrate that thermal annealing can increase interlayer coupling in the van der Waals heterostructures,and after thermally induced band hybridization such heterostructure behaves more like an artificial new solid,rather than just the combination of two individual TMD components.We also carry out experimental and theoretical studies of the electric controllable direct and indirect infrared interlayer excitons in such system.Our study reveals the impact of interlayer coupling on interlayer excitons and will shed light on the understanding and engineering of layer-controlled spin-valley configuration in twisted van der Waals heterostructures.