Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor t...Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor transport method.We measured the magnetization,longitudinal resistivityρxx(T,H),Hall resistivityρxy(T,H),as well as performed calculations of the electronic band structure.It was found that V_(1/3)TaS_(2) is an A-type antiferromagnet with the Neel temperature T_(N)=6.20 K,and exhibits a negative magnetoresistance(MR)near T_(N).Both band structure calculations and Hall resistivity measurements demonstrated it is a magnetic semimetal.展开更多
Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared...Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.展开更多
A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Mont...A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Monte Carlo simulations,we present a theoretical proposal for a stacking-dependent exchange bias in two-dimensional compensated van der Waals ferromagnetic/antiferromagnetic bilayer heterostructures. The exchange bias effect emerges in stacking registries that accommodate inhomogeneous interlayer magnetic interactions between the ferromagnetic layer and different spin sublattices of the antiferromagnetic layer. Moreover, the on/off switching and polarity reversal of the exchange bias can be achieved by interlayer sliding, and the strength can be modulated using an external electric field. Our findings push the limits of exchange bias systems to extreme bilayer thickness in two-dimensional van der Waals heterostructures, potentially stimulating new experimental investigations and applications.展开更多
We conducted a comparative study of the magnetic and transport properties of single-crystalline LaCo_(2)As_(2) and NdCo_(2)As_(2).LaCo_(2)As_(2) is a soft metallic ferromagnet which exhibits purely intrinsic anomalous...We conducted a comparative study of the magnetic and transport properties of single-crystalline LaCo_(2)As_(2) and NdCo_(2)As_(2).LaCo_(2)As_(2) is a soft metallic ferromagnet which exhibits purely intrinsic anomalous Hall effect(AHE) due to Co-3d electrons. With Nd-4f electronic magnetism, ferrimagnetic NdCo_(2)As_(2) manifests pronounced sign reversal and multiple hysteresis loops in temperature-and field-dependent magnetization, Hall resistivity, and magnetoresistance, due to complicated magnetic structural changes. We reveal that the AHE for NdCo_(2)As_(2) is stemming from the Co sub-lattice and deduce its phase diagram which includes magnetic compensation and two meta-magnetic phase transitions. The sensitivity of the Hall effect on the details of the magnetic structures in ferrimagnetic NdCo_(2)As_(2) provides a unique opportunity to explore the magnetic interaction between 4f and 3d electrons and its impact on the electronic structure.展开更多
Control and detection of antiferromagnetic topological materials are challenging since the total magnetization vanishes.Here we investigate the magneto-optical Kerr and Faraday effects in bilayer antiferromagnetic ins...Control and detection of antiferromagnetic topological materials are challenging since the total magnetization vanishes.Here we investigate the magneto-optical Kerr and Faraday effects in bilayer antiferromagnetic insulator Mn Bi2Te4.We find that by breaking the combined mirror symmetries with either perpendicular electric field or external magnetic moment,Kerr and Faraday effects occur.Under perpendicular electric field,antiferromagnetic topological insulators(AFMTI)show sharp peaks at the interband transition threshold,whereas trivial insulators show small adjacent positive and negative peaks.Gate voltage and Fermi energy can be tuned to reveal the differences between AFMTI and trivial insulators.We find that AFMTI with large antiferromagnetic order can be proposed as a pure magneto-optical rotator due to sizable Kerr(Faraday)angles and vanishing ellipticity.Under external magnetic moment,AFMTI and trivial insulators are significantly different in the magnitude of Kerr and Faraday angles and ellipticity.For the qualitative behaviors,AFMTI shows distinct features of Kerr and Faraday angles when the spin configurations of the system change.These phenomena provide new possibilities to optically detect and manipulate the layered topological antiferromagnets.展开更多
Topological magnetotransport in non-collinear antiferromagnets has attracted extensive attention due to the exotic phenomena such as large anomalous Hall effect(AHE),magnetic spin Hall effect,and chiral anomaly.The ma...Topological magnetotransport in non-collinear antiferromagnets has attracted extensive attention due to the exotic phenomena such as large anomalous Hall effect(AHE),magnetic spin Hall effect,and chiral anomaly.The materials exhibiting topological antiferromagnetic physics are typically limited in special Mn_3X family such as Mn_3Sn and Mn_3Ge.Exploring the topological magnetotransport in common antiferromagnetic materials widely used in spintronics will not only enrich the platforms for investigating the non-collinear antiferromagnetic physics,but also have great importance for driving the nontrivial topological properties towards practical applications.Here,we report remarkable AHE,anisotropic and negative parallel magnetoresistance in the magnetron-sputtered Ir_(20)Mn_(80)antiferromagnet,which is one of the most widely used antiferromagnetic materials in industrial spintronics.The ab initio calculations suggest that the Ir_4Mn_(16)(IrMn_4)or Mn_3Ir nanocrystals hold nontrivial electronic band structures,which may contribute to the observed intriguing magnetotransport properties in the Ir_(20)Mn_(80).Further,we demonstrate the spin–orbit torque switching of the antiferromagnetic Ir_(20)Mn_(80)by the spin Hall current of Pt.The presented results highlight a great potential of the magnetron-sputtered Ir_(20)Mn_(80)film for exploring the topological antiferromagnet-based physics and spintronics applications.展开更多
Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra.Here we demonstrate that a spin gap exists in the quasi-1D Heise...Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra.Here we demonstrate that a spin gap exists in the quasi-1D Heisenberg antiferromagnet CoTi2O5 with highly ordered Co2+/Ti4+occupation,in which the Co2+ions with S=3/2 form a 1D spin chain along the a-axis.CoTi2O5 undergoes an antiferromagnetic transition at TN~24 K and exhibits obvious anisotropic magnetic susceptibility even in the paramagnetic region.Although a gapless magnetic ground state is usually expected in a quasi-1D Heisenberg antiferromagnet with half-integer spins,by analyzing the specific heat,the thermal conductivity,and the spin-lattice relaxation rate(1/T1)as a function of temperature,we found that a spin gap is opened in the spin-excitation spectrum of CoTi2O5 around TN,manifested by the rapid decrease of magnetic specific heat to zero,the double-peak characteristic in thermal conductivity,and the exponential decay of 1/T1 below TN.Both the magnetic measurements and the first-principles calculations results indicate that there is spin-orbit coupling in CoTi2O5,which induces the magnetic anisotropy in CoTi2O5,and then opens the spin gap at low temperature.展开更多
We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used ...We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.展开更多
The magnetic properties of an antiferromagnetic bond alternating spin-1/2 zigzag chain with asymmetrical ferromagnetic next-nearest-neighbour exchange interactions at finite temperature are investigated by using the m...The magnetic properties of an antiferromagnetic bond alternating spin-1/2 zigzag chain with asymmetrical ferromagnetic next-nearest-neighbour exchange interactions at finite temperature are investigated by using the many-body Green's function theory.It is found that the ferrimagnetic ordering does not appear in the symmetrical next-nearestneighbour coupling case,and takes place only for the asymmetrical next-nearest-neighbour case at finite temperature rather than the ground state.Furthermore,as the asymmetry degree of the next-nearest-neighbour exchange interactions increases,the ferrimagnetism becomes more and more dominant.It is shown that the elementary excitation spectra are responsible for the observed magnetic behaviour.展开更多
We use the mean-field approximation of Dyson–Maleev representation to study an XXZ Heisenberg ferrimagnetic spin chain with single-ion anisotropy. By solving the self-consistent equations with different anisotropies,...We use the mean-field approximation of Dyson–Maleev representation to study an XXZ Heisenberg ferrimagnetic spin chain with single-ion anisotropy. By solving the self-consistent equations with different anisotropies, λ and D respectively,the energy spectrums, internal energy, static susceptibility and specific heat are calculated. Especially, the quantum phase transition of the magnetization plateau induced by single-ion anisotropy D is obtained in the model of the ferrimagnetic spin chain by using Dyson–Maleev mean-field theory.展开更多
We exploit a scheme to obtain a long-lived entanglement using a driven central spin interacting with an antiferromagnetic spin bath. Our numerical results show the effects of different parameters on the population inv...We exploit a scheme to obtain a long-lived entanglement using a driven central spin interacting with an antiferromagnetic spin bath. Our numerical results show the effects of different parameters on the population inversion and the entanglement dynamics in terms of the linear entropy. It is shown that the long-lived entanglement is an intriguing result corresponding to the collapse region of the atomic inversion. As illustration, we examine the long-time interaction of the entanglement under the resonance and off-resonance regimes.展开更多
Rare earth iron garnets R3Fe5-x Mn x O12(R=Pr,Nd,Sm,Eu) were prepared through mild hydrothermal method.The initial alkalinity of solutions was thought to play an important role in governing the content of Mn.The effec...Rare earth iron garnets R3Fe5-x Mn x O12(R=Pr,Nd,Sm,Eu) were prepared through mild hydrothermal method.The initial alkalinity of solutions was thought to play an important role in governing the content of Mn.The effect of substitution Fe3+ ions by Mn3+ ions on magnetic properties was investigated.The saturation magnetizations of Mn-doped samples are larger than that of corresponding parent compounds due to the moment of Mn3+ ion being smaller than that of Fe3+.It is clearly shown that incorporation of Mn3+ gives rise to significant variations in the Curie temperature.With increasing of Mn content x,Curie temperatures reduced sharply for the garnets,which could be explained by the exchange interaction between a-d Fe3+ being reduced in these compounds.展开更多
We report the detailed physical properties of quaternary compound Ba2BiFeS5 with the key structural ingredient of isolated FeS4 tetrahedra.Magnetization and heat capacity measurements clearly indicate that Ba2BiFeS5 h...We report the detailed physical properties of quaternary compound Ba2BiFeS5 with the key structural ingredient of isolated FeS4 tetrahedra.Magnetization and heat capacity measurements clearly indicate that Ba2BiFeS5 has a paramagnetic to antiferromagnetic transition at about 30 K.The calculated magnetic entropy above ordering temperature is much smaller than theoretical value for high-spin Fe^3+ion with S=5/2,implying the possible short-range antiferromagnetic fluctuation in Ba2BiFeS5.展开更多
The aims of the work were to study the effect of Ge (0-6wt. %) on the paramagnetic-antiferromagnetic transition and martensitic transformation of Fe-Mn alloy using the susceptibility, microstructure examination, X-ray...The aims of the work were to study the effect of Ge (0-6wt. %) on the paramagnetic-antiferromagnetic transition and martensitic transformation of Fe-Mn alloy using the susceptibility, microstructure examination, X-ray diffraction (XRD) and lattice parameter measurement. Ge lowers the Neel temperature, TN, and enhances the mag-netic susceptibility X, changing the Pauli paramagnetism above TN to paramagnetism state obeying the Curie Weiss law, which is essentially similar to that of γ-Fe-Mn alloys containing Al or Si; Ge depresses γ → ε martensitic transformation, which attribute to Ge increasing the stacking fault energy; Moreover, Ge increases the lat-tice parameter of 7 phase, and low content Ge increases the lattice parameter of γphase more than that of high Ge content. Comparing Ge(4s2 4p2 ) with Si(3s2 3p2 ) and Al(3s2 3p1), which have the same outer-shell of electron structures, we found that their effects on the martensitic transformation of Fe-Mn alloy are completely different. The result suggests the outer-shell of electron is not the main factor of governing the Ms temperature of Fe-Mn alloy although it is essential in the alloy's antiferromagnetic transition. The relation among the Ms temperature, stacking fault energy and lattice parameter of austenite, has been discussed in brief.展开更多
Polycrystalline samples of La0.67-xPrxCa0.33MnO3(x=0~0.67) were synthesized by a conventional solid state reaction. X-ray diffraction revealed that the samples were all of single phase with an orthorhombic distorted ...Polycrystalline samples of La0.67-xPrxCa0.33MnO3(x=0~0.67) were synthesized by a conventional solid state reaction. X-ray diffraction revealed that the samples were all of single phase with an orthorhombic distorted perovskite structure. The magnetization depended on temperature measured in FC (field cooling) and ZFC (zero field cooling). It revealed that the compounds mainly underwent a ferromagnetic transition (TC) when the less Pr doped (x<0.4). With increasing doping content (x>0.5), the ferromagnetic transition disappeared and the antiferromagnetic transition (TN) was dominant. Charge ordering (TCO) also emerged when x>0.36. The transition temperatures TN and TCO would change with the Pr doping content. The phase separation could be used to explain these characters occurred in these polycrystalline samples.展开更多
An effective-field treatment for the two dimensional Isingantiferromagent-antiferromagnetic superlattice(AFAFS)without external field is pres-ented.The critical temperature dependence of the number of laycrs of superl...An effective-field treatment for the two dimensional Isingantiferromagent-antiferromagnetic superlattice(AFAFS)without external field is pres-ented.The critical temperature dependence of the number of laycrs of superlattice cell andthe temperature dependence of magnetization of each layer in the superlattice are investi-gated.The similarity of the magnetic properties of AFAFS and those offerromagnet-ferromagnetic superlattice(FFS)is also discussed.展开更多
In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field(H_(ex)) and strength(-J_(iec)) in synthetic antiferromagnetic(SAF) structure of [Pt(0.6)/Co(0.6)]_2/Ru(t_(Ru...In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field(H_(ex)) and strength(-J_(iec)) in synthetic antiferromagnetic(SAF) structure of [Pt(0.6)/Co(0.6)]_2/Ru(t_(Ru))/[Co(0.6)/Pt(0.6)]_4 multilayers with perpendicular anisotropy. Depending on the thickness of the spacing ruthenium(Ru) layer, the observed interlayer exchange coupling can be either ferromagnetic or antiferromagnetic. The H_(ex) were studied by measuring the magnetization hysteresis loops in the temperature range from 100 K to 700 K as well as the theoretical calculation of the-J_(iec). It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The H_(ex)exhibits either a linear or a non-linear dependence on the temperature for different thickness of Ru. Furthermore, our SAF multilayers show a high thermal stability even up to 600 K(H_(ex)= 3.19 kOe,-J_(iec)= 1.97 erg/cm^2 for t_(Ru)=0.6 nm, the unit 1 Oe = 79.5775 A·m^(-1)), which was higher than the previous studies.展开更多
Electrical spin,which is the key element of spintronics,has been regarded as a powerful substitute for the electrical charge in the next generation of information technology,in which spin plays the role of the carrier...Electrical spin,which is the key element of spintronics,has been regarded as a powerful substitute for the electrical charge in the next generation of information technology,in which spin plays the role of the carrier of information and/or energy in a similar way to the electrical charge in electronics.Spin-transport phenomena in different materials are central topics of spintronics.Unlike electrical charge,spin transport does not depend on electron motion,particularly spin can be transported in insulators without accompanying Joule heating.Therefore,insulators are considered to be ideal materials for spin conductors,in which magnetic insulators are the most compelling systems.Recently,we experimentally studied and theoretically discussed spin transport in various antiferromagnetic systems and identified spin susceptibility and the Néel vector as the most important factors for spin transport in antiferromagnetic systems.Herein,we summarize our experimental results,physical nature,and puzzles unknown.Further challenges and potential applications are also discussed.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFA1403202)the National Natural Science Foundation of China(Grant Nos.NSFC-12074335,11974095,5177115,11974095,and 12188101)the Natural Science Foundation of Shaanxi Province of China(Grant No.2022JM-028).
文摘Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor transport method.We measured the magnetization,longitudinal resistivityρxx(T,H),Hall resistivityρxy(T,H),as well as performed calculations of the electronic band structure.It was found that V_(1/3)TaS_(2) is an A-type antiferromagnet with the Neel temperature T_(N)=6.20 K,and exhibits a negative magnetoresistance(MR)near T_(N).Both band structure calculations and Hall resistivity measurements demonstrated it is a magnetic semimetal.
基金Project supported by the open research fund of Songshan Lake Materials Laboratory(Grant No.2021SLABFN11)the National Natural Science Foundation of China(Grant Nos.U2130101 and 92165204)+5 种基金Natural Science Foundation of Guangdong Province(Grant No.2022A1515010035)Guangzhou Basic and Applied Basic Research Foundation(Grant No.202201011798)the Open Project of Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)the Open Project of Key Laboratory of Optoelectronic Materials and Technologies(Grant No.OEMT-2023-ZTS-01)the National Key R&D Program of China(Grant Nos.2023YFF0718400 and 2023YFA1406500)(national)college students innovation and entrepreneurship training program,Sun Yat-sen University(Grant No.202310359).
文摘Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.
基金Project supported by the National Key Research and Development Program of China (Grant No.2019YFA0210004)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB30000000)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No.WK3510000013)the National Supercomputing Center in Tianjin。
文摘A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Monte Carlo simulations,we present a theoretical proposal for a stacking-dependent exchange bias in two-dimensional compensated van der Waals ferromagnetic/antiferromagnetic bilayer heterostructures. The exchange bias effect emerges in stacking registries that accommodate inhomogeneous interlayer magnetic interactions between the ferromagnetic layer and different spin sublattices of the antiferromagnetic layer. Moreover, the on/off switching and polarity reversal of the exchange bias can be achieved by interlayer sliding, and the strength can be modulated using an external electric field. Our findings push the limits of exchange bias systems to extreme bilayer thickness in two-dimensional van der Waals heterostructures, potentially stimulating new experimental investigations and applications.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFB1502502)the National Natural Science Foundation of China(Grant Nos.12141002 and 12225401)+6 种基金the Fund from Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratorysupported by the Interdisciplinary Program of Wuhan National High Magnetic Field Center(Grant No.WHMFC202123)Huazhong University of Science and Technologysupported by the National Natural Science Foundation of China(Grant Nos.12074041 and 11674030)the Foundation of the National Key Laboratory of Shock Wave and Detonation Physics(Grant No.6142A03191005)the National Key Research and Development Program of China(Grant No.2016YFA0302300)the startup funding of Beijing Normal University。
文摘We conducted a comparative study of the magnetic and transport properties of single-crystalline LaCo_(2)As_(2) and NdCo_(2)As_(2).LaCo_(2)As_(2) is a soft metallic ferromagnet which exhibits purely intrinsic anomalous Hall effect(AHE) due to Co-3d electrons. With Nd-4f electronic magnetism, ferrimagnetic NdCo_(2)As_(2) manifests pronounced sign reversal and multiple hysteresis loops in temperature-and field-dependent magnetization, Hall resistivity, and magnetoresistance, due to complicated magnetic structural changes. We reveal that the AHE for NdCo_(2)As_(2) is stemming from the Co sub-lattice and deduce its phase diagram which includes magnetic compensation and two meta-magnetic phase transitions. The sensitivity of the Hall effect on the details of the magnetic structures in ferrimagnetic NdCo_(2)As_(2) provides a unique opportunity to explore the magnetic interaction between 4f and 3d electrons and its impact on the electronic structure.
基金Project supported by the National Natural Science Foundation of China(Grant No.11904062)the Starting Research Fund from Guangzhou University(Grant No.RQ2020076)Guangzhou Basic Research Program,jointed funded by Guangzhou University(Grant No.202201020186)。
文摘Control and detection of antiferromagnetic topological materials are challenging since the total magnetization vanishes.Here we investigate the magneto-optical Kerr and Faraday effects in bilayer antiferromagnetic insulator Mn Bi2Te4.We find that by breaking the combined mirror symmetries with either perpendicular electric field or external magnetic moment,Kerr and Faraday effects occur.Under perpendicular electric field,antiferromagnetic topological insulators(AFMTI)show sharp peaks at the interband transition threshold,whereas trivial insulators show small adjacent positive and negative peaks.Gate voltage and Fermi energy can be tuned to reveal the differences between AFMTI and trivial insulators.We find that AFMTI with large antiferromagnetic order can be proposed as a pure magneto-optical rotator due to sizable Kerr(Faraday)angles and vanishing ellipticity.Under external magnetic moment,AFMTI and trivial insulators are significantly different in the magnitude of Kerr and Faraday angles and ellipticity.For the qualitative behaviors,AFMTI shows distinct features of Kerr and Faraday angles when the spin configurations of the system change.These phenomena provide new possibilities to optically detect and manipulate the layered topological antiferromagnets.
基金the Tencent Foundation through the XPLORER PRIZEthe National Key Research and Development Program of China(Grant Nos.2018YFB0407602 and 2021YFB3601303)the National Natural Science Foundation of China(Grant Nos.61627813,11904017,92164206,and 61571023)。
文摘Topological magnetotransport in non-collinear antiferromagnets has attracted extensive attention due to the exotic phenomena such as large anomalous Hall effect(AHE),magnetic spin Hall effect,and chiral anomaly.The materials exhibiting topological antiferromagnetic physics are typically limited in special Mn_3X family such as Mn_3Sn and Mn_3Ge.Exploring the topological magnetotransport in common antiferromagnetic materials widely used in spintronics will not only enrich the platforms for investigating the non-collinear antiferromagnetic physics,but also have great importance for driving the nontrivial topological properties towards practical applications.Here,we report remarkable AHE,anisotropic and negative parallel magnetoresistance in the magnetron-sputtered Ir_(20)Mn_(80)antiferromagnet,which is one of the most widely used antiferromagnetic materials in industrial spintronics.The ab initio calculations suggest that the Ir_4Mn_(16)(IrMn_4)or Mn_3Ir nanocrystals hold nontrivial electronic band structures,which may contribute to the observed intriguing magnetotransport properties in the Ir_(20)Mn_(80).Further,we demonstrate the spin–orbit torque switching of the antiferromagnetic Ir_(20)Mn_(80)by the spin Hall current of Pt.The presented results highlight a great potential of the magnetron-sputtered Ir_(20)Mn_(80)film for exploring the topological antiferromagnet-based physics and spintronics applications.
基金supported by the National Natural Science Foundation of China (Grant No. 52372003)the Funds from Beijing National Laboratory for Condensed Matter Physics
文摘Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra.Here we demonstrate that a spin gap exists in the quasi-1D Heisenberg antiferromagnet CoTi2O5 with highly ordered Co2+/Ti4+occupation,in which the Co2+ions with S=3/2 form a 1D spin chain along the a-axis.CoTi2O5 undergoes an antiferromagnetic transition at TN~24 K and exhibits obvious anisotropic magnetic susceptibility even in the paramagnetic region.Although a gapless magnetic ground state is usually expected in a quasi-1D Heisenberg antiferromagnet with half-integer spins,by analyzing the specific heat,the thermal conductivity,and the spin-lattice relaxation rate(1/T1)as a function of temperature,we found that a spin gap is opened in the spin-excitation spectrum of CoTi2O5 around TN,manifested by the rapid decrease of magnetic specific heat to zero,the double-peak characteristic in thermal conductivity,and the exponential decay of 1/T1 below TN.Both the magnetic measurements and the first-principles calculations results indicate that there is spin-orbit coupling in CoTi2O5,which induces the magnetic anisotropy in CoTi2O5,and then opens the spin gap at low temperature.
基金Project supported by the Natural Science Basic Research Program of Shaanxi(Program Nos.2023KJXX-064 and 2021JQ-748)the National Natural Science Foundation of China(Grant Nos.11804213 and 12174238)Scientific Research Foundation of Shaanxi University of Technology(Grant No.SLGRCQD2006).
文摘We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.
基金Project supported by the National Natural Science Foundation of China (Grant No.1010804034)the Science Foundation of China for Three Gorges University (Grant No.KJ2009B012)
文摘The magnetic properties of an antiferromagnetic bond alternating spin-1/2 zigzag chain with asymmetrical ferromagnetic next-nearest-neighbour exchange interactions at finite temperature are investigated by using the many-body Green's function theory.It is found that the ferrimagnetic ordering does not appear in the symmetrical next-nearestneighbour coupling case,and takes place only for the asymmetrical next-nearest-neighbour case at finite temperature rather than the ground state.Furthermore,as the asymmetry degree of the next-nearest-neighbour exchange interactions increases,the ferrimagnetism becomes more and more dominant.It is shown that the elementary excitation spectra are responsible for the observed magnetic behaviour.
基金Project supported by the National Natural Science Foundation of China(Grant No.10774035)the Qianjiang RenCai Program of Zhejiang Province,China(Grant No.2007R0010)
文摘We use the mean-field approximation of Dyson–Maleev representation to study an XXZ Heisenberg ferrimagnetic spin chain with single-ion anisotropy. By solving the self-consistent equations with different anisotropies, λ and D respectively,the energy spectrums, internal energy, static susceptibility and specific heat are calculated. Especially, the quantum phase transition of the magnetization plateau induced by single-ion anisotropy D is obtained in the model of the ferrimagnetic spin chain by using Dyson–Maleev mean-field theory.
文摘We exploit a scheme to obtain a long-lived entanglement using a driven central spin interacting with an antiferromagnetic spin bath. Our numerical results show the effects of different parameters on the population inversion and the entanglement dynamics in terms of the linear entropy. It is shown that the long-lived entanglement is an intriguing result corresponding to the collapse region of the atomic inversion. As illustration, we examine the long-time interaction of the entanglement under the resonance and off-resonance regimes.
基金Supported by the National Natural Science Foundation of China(Nos.90922034,20771042)
文摘Rare earth iron garnets R3Fe5-x Mn x O12(R=Pr,Nd,Sm,Eu) were prepared through mild hydrothermal method.The initial alkalinity of solutions was thought to play an important role in governing the content of Mn.The effect of substitution Fe3+ ions by Mn3+ ions on magnetic properties was investigated.The saturation magnetizations of Mn-doped samples are larger than that of corresponding parent compounds due to the moment of Mn3+ ion being smaller than that of Fe3+.It is clearly shown that incorporation of Mn3+ gives rise to significant variations in the Curie temperature.With increasing of Mn content x,Curie temperatures reduced sharply for the garnets,which could be explained by the exchange interaction between a-d Fe3+ being reduced in these compounds.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0300504)the National Natural Science Foundation of China(Grant Nos.11574394,11774423,and 11822412)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(RUC)(Grant Nos.15XNLQ07,18XNLG14,and 19XNLG17)
文摘We report the detailed physical properties of quaternary compound Ba2BiFeS5 with the key structural ingredient of isolated FeS4 tetrahedra.Magnetization and heat capacity measurements clearly indicate that Ba2BiFeS5 has a paramagnetic to antiferromagnetic transition at about 30 K.The calculated magnetic entropy above ordering temperature is much smaller than theoretical value for high-spin Fe^3+ion with S=5/2,implying the possible short-range antiferromagnetic fluctuation in Ba2BiFeS5.
基金The project was supported by the National Natural Science Foundation of China (Grant No.59601007).
文摘The aims of the work were to study the effect of Ge (0-6wt. %) on the paramagnetic-antiferromagnetic transition and martensitic transformation of Fe-Mn alloy using the susceptibility, microstructure examination, X-ray diffraction (XRD) and lattice parameter measurement. Ge lowers the Neel temperature, TN, and enhances the mag-netic susceptibility X, changing the Pauli paramagnetism above TN to paramagnetism state obeying the Curie Weiss law, which is essentially similar to that of γ-Fe-Mn alloys containing Al or Si; Ge depresses γ → ε martensitic transformation, which attribute to Ge increasing the stacking fault energy; Moreover, Ge increases the lat-tice parameter of 7 phase, and low content Ge increases the lattice parameter of γphase more than that of high Ge content. Comparing Ge(4s2 4p2 ) with Si(3s2 3p2 ) and Al(3s2 3p1), which have the same outer-shell of electron structures, we found that their effects on the martensitic transformation of Fe-Mn alloy are completely different. The result suggests the outer-shell of electron is not the main factor of governing the Ms temperature of Fe-Mn alloy although it is essential in the alloy's antiferromagnetic transition. The relation among the Ms temperature, stacking fault energy and lattice parameter of austenite, has been discussed in brief.
基金the Nature Science Foundation of Hebei Province (E2006000058)Doctor Foundation of Hebei Univ.Tech.
文摘Polycrystalline samples of La0.67-xPrxCa0.33MnO3(x=0~0.67) were synthesized by a conventional solid state reaction. X-ray diffraction revealed that the samples were all of single phase with an orthorhombic distorted perovskite structure. The magnetization depended on temperature measured in FC (field cooling) and ZFC (zero field cooling). It revealed that the compounds mainly underwent a ferromagnetic transition (TC) when the less Pr doped (x<0.4). With increasing doping content (x>0.5), the ferromagnetic transition disappeared and the antiferromagnetic transition (TN) was dominant. Charge ordering (TCO) also emerged when x>0.36. The transition temperatures TN and TCO would change with the Pr doping content. The phase separation could be used to explain these characters occurred in these polycrystalline samples.
基金The Project supported by National Natural Science Foundation of China the Magnetism Laboratory,Academia Sinica.
文摘An effective-field treatment for the two dimensional Isingantiferromagent-antiferromagnetic superlattice(AFAFS)without external field is pres-ented.The critical temperature dependence of the number of laycrs of superlattice cell andthe temperature dependence of magnetization of each layer in the superlattice are investi-gated.The similarity of the magnetic properties of AFAFS and those offerromagnet-ferromagnetic superlattice(FFS)is also discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.11704191)the Jiangsu Specially-Appointed Professor,the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20171026)the Six-Talent Peaks Project in Jiangsu Province,China(Grant No.XYDXX-038)
文摘In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field(H_(ex)) and strength(-J_(iec)) in synthetic antiferromagnetic(SAF) structure of [Pt(0.6)/Co(0.6)]_2/Ru(t_(Ru))/[Co(0.6)/Pt(0.6)]_4 multilayers with perpendicular anisotropy. Depending on the thickness of the spacing ruthenium(Ru) layer, the observed interlayer exchange coupling can be either ferromagnetic or antiferromagnetic. The H_(ex) were studied by measuring the magnetization hysteresis loops in the temperature range from 100 K to 700 K as well as the theoretical calculation of the-J_(iec). It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The H_(ex)exhibits either a linear or a non-linear dependence on the temperature for different thickness of Ru. Furthermore, our SAF multilayers show a high thermal stability even up to 600 K(H_(ex)= 3.19 kOe,-J_(iec)= 1.97 erg/cm^2 for t_(Ru)=0.6 nm, the unit 1 Oe = 79.5775 A·m^(-1)), which was higher than the previous studies.
基金Project supported by the National Natural Science Foundation of China(Grant No.11874098)LiaoNing Revitalization Talents Program(Grant No.XLYC1807156)the Fundamental Research Funds for the Central Universities(Grant No.DUT17RC(3)073)
文摘Electrical spin,which is the key element of spintronics,has been regarded as a powerful substitute for the electrical charge in the next generation of information technology,in which spin plays the role of the carrier of information and/or energy in a similar way to the electrical charge in electronics.Spin-transport phenomena in different materials are central topics of spintronics.Unlike electrical charge,spin transport does not depend on electron motion,particularly spin can be transported in insulators without accompanying Joule heating.Therefore,insulators are considered to be ideal materials for spin conductors,in which magnetic insulators are the most compelling systems.Recently,we experimentally studied and theoretically discussed spin transport in various antiferromagnetic systems and identified spin susceptibility and the Néel vector as the most important factors for spin transport in antiferromagnetic systems.Herein,we summarize our experimental results,physical nature,and puzzles unknown.Further challenges and potential applications are also discussed.