Recently, spin-momentum-locked topological surface states(SSs) have attracted significant attention in spintronics.Owing to spin-momentum locking, the direction of the spin is locked at right angles with respect to ...Recently, spin-momentum-locked topological surface states(SSs) have attracted significant attention in spintronics.Owing to spin-momentum locking, the direction of the spin is locked at right angles with respect to the carrier momentum.In this paper, we briefly review the exotic transport properties induced by topological SSs in topological-insulator(TI)nanostructures, which have larger surface-to-volume ratios than those of bulk TI materials. We discuss the electrical spin generation in TIs and its effect on the transport properties. A current flow can generate a pure in-plane spin polarization on the surface, leading to a current-direction-dependent magnetoresistance in spin valve devices based on TI nanostructures.A relative momentum shift of two coupled topological SSs also generates net spin polarization and induces an in-plane anisotropic negative magnetoresistance. Therefore, the spin-momentum locking can enable the broad tuning of the spin transport properties of topological devices for spintronic applications.展开更多
Naturally existing in-plane hyperbolic polaritons and the associated optical topological transitions,which avoid the nano-structuring to achieve hyperbolicity,can outperform their counterparts in artificial metasurfac...Naturally existing in-plane hyperbolic polaritons and the associated optical topological transitions,which avoid the nano-structuring to achieve hyperbolicity,can outperform their counterparts in artificial metasurfaces.Such plasmon polaritons are rare,but experimentally revealed recently in WTe_(2)van der Waals thin films.Different from phonon polaritons,hyperbolic plasmon polaritons originate from the interplay of free carrier Drude response and interband transitions,which promise good intrinsic tunability.However,tunable in-plane hyperbolic plasmon polariton and its optical topological transition of the isofrequency contours to the elliptic topology in a natural material have not been realized.Here we demonstrate the tuning of the optical topological transition through Mo doping and temperature.The optical topological transition energy is tuned over a wide range,with frequencies ranging from 429 cm^(−1)(23.3 microns)for pure WTe_(2)to 270 cm^(−1)(37.0 microns)at the 50%Mo-doping level at 10 K.Moreover,the temperature-induced blueshift of the optical topological transition energy is also revealed,enabling active and reversible tuning.Surprisingly,the localized surface plasmon resonance in skew ribbons shows unusual polarization dependence,accurately manifesting its topology,which renders a reliable means to track the topology with far-field techniques.Our results open an avenue for reconfigurable photonic devices capable of plasmon polariton steering,such as canaling,focusing,and routing,and pave the way for low-symmetry plasmonic nanophotonics based on anisotropic natural materials.展开更多
Dirac nodal-line semimetals with the linear bands crossing along a line or loop, represent a new topological state of matter. Here, by carrying out magnetotransport measurements and performing first-principle calculat...Dirac nodal-line semimetals with the linear bands crossing along a line or loop, represent a new topological state of matter. Here, by carrying out magnetotransport measurements and performing first-principle calculations, we demonstrate that such a state has been realized in high-quality single crystals of SrAs_3.We obtain the nontrivial ∏ Berry phase by analysing the Shubnikov-de Haas quantum oscillations. We also observe a robust negative longitudinal magnetoresistance induced by the chiral anomaly.Accompanying first-principles calculations identifies that a single hole pocket enclosing the loop nodes is responsible for these observations.展开更多
Performing angle-resolved photoemission spectroscopy(ARPES) and theoretical calculations for ZrSnTe, we find a nodal line in the kx-ky plane with a tiny gap and two nodal lines without gaps along the kzdirection. The ...Performing angle-resolved photoemission spectroscopy(ARPES) and theoretical calculations for ZrSnTe, we find a nodal line in the kx-ky plane with a tiny gap and two nodal lines without gaps along the kzdirection. The constant energy contours are plotted in the kx-ky plane at a photon energy of 30 e V to examine the gapping feature of the nodal line. In addition, we depict the band dispersions along the Γ-M and Γ-X directions from the ARPES images at photon energies ranging from 24 to 40 e V. The kz mapping confirms the presence of stable Dirac points with obvious kzdependences along the M-A and X-R directions. In this paper, we report the two types of nodal lines associated with the theoretical local-density approximation calculations, broadening the horizons of nodal-line semimetal research.展开更多
Unsaturated magnetoresistance (MR) has been reported in type-II Weyl semimetal WTe2, manifested as a perfect compensation of opposite carriers. We report linear MR (LMR) in WTe2 crystals, the onset of which was id...Unsaturated magnetoresistance (MR) has been reported in type-II Weyl semimetal WTe2, manifested as a perfect compensation of opposite carriers. We report linear MR (LMR) in WTe2 crystals, the onset of which was identified by constructing the MR mobility spectra for weak fields. The LMR further increased and became dominant for fields stronger than 20 T, while the parabolic MR gradually decayed. The LMR was also observed in high-pressure conditions.展开更多
Cleft lip and/or palate(CL/P)is a most common craniofacial birth defect which has multifactorial etiology.In our study,we aimed to discover the underlying etiological gene variation in a Chinese family diagnosed as no...Cleft lip and/or palate(CL/P)is a most common craniofacial birth defect which has multifactorial etiology.In our study,we aimed to discover the underlying etiological gene variation in a Chinese family diagnosed as non-syndromic CL/P(NSCL/P).The blood sample of the proband and her parents were detected by whole exome sequencing.The Mendelian inheritance pattern,allele frequency,variation location,function analysis and literature search were applied to filtrate and screen the mutation.Besides,the candidates were confirmed by Sanger sequencing.We meanwhile explored the conservative analysis and protein homology simulation.As a result,a start-lost mutation c.1A>GAtg/Gtg in the Frizzled-6(FZD6)gene predicting p.Met1 was detected.The variation has not been reported before and was predicted to be harmful.The alteration caused missing of two starting amino acids that are evolutionarily conserved for FZD6 protein.Moreover,the specific structure of the mutant protein obviously changed according to the results of the homologous model.In conclusion,the results suggest c.1A>GAtg/Gtg in the FZD6(NM_001164616)might be the genetic etiology for non-syndromic CL/P in this pedigree.Furthermore,this finding provided new etiologic information,supplementing the evidence that FZD6 is a strong potential gene for CL/P.展开更多
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2014CB921103 and 2017YFA0206304)the National Natural Science Foundation of China(Grant Nos.61822403,11874203,U1732159,and U1732273)+1 种基金Fundamental Research Funds for the Central Universities,China(Grant No.021014380080)Collaborative Innovation Center of Solid-State Lighting and Energy-Saving Electronics,China
文摘Recently, spin-momentum-locked topological surface states(SSs) have attracted significant attention in spintronics.Owing to spin-momentum locking, the direction of the spin is locked at right angles with respect to the carrier momentum.In this paper, we briefly review the exotic transport properties induced by topological SSs in topological-insulator(TI)nanostructures, which have larger surface-to-volume ratios than those of bulk TI materials. We discuss the electrical spin generation in TIs and its effect on the transport properties. A current flow can generate a pure in-plane spin polarization on the surface, leading to a current-direction-dependent magnetoresistance in spin valve devices based on TI nanostructures.A relative momentum shift of two coupled topological SSs also generates net spin polarization and induces an in-plane anisotropic negative magnetoresistance. Therefore, the spin-momentum locking can enable the broad tuning of the spin transport properties of topological devices for spintronic applications.
基金H.Y.is grateful to the financial support from the National Key Research and Development Program of China(Grant Nos.2022YFA1404700 and 2021YFA1400100)the National Natural Science Foundation of China(Grant No.12074085)+7 种基金the Natural Science Foundation of Shanghai(Grant No.23XD1400200)C.W.is grateful to the financial support from the National Natural Science Foundation of China(Grant Nos.12274030,11704075)the National Key Research and Development Program of China(Grant No.2022YFA1403400)F.S.acknowledges the financial support from the National Key Research and Development Program of China(Grant No.2017YFA0303203)the National Natural Science Foundation of China(Grant Nos.92161201,12025404,11904165,and 12274208)the Natural Science Foundation of Jiangsu Province(Grant No.BK20190286)S.H.is grateful to the financial support from the China Postdoctoral Science Foundation(Grant No.2020TQ0078)Part of the experimental work was carried out in Fudan Nanofabrication Lab.
文摘Naturally existing in-plane hyperbolic polaritons and the associated optical topological transitions,which avoid the nano-structuring to achieve hyperbolicity,can outperform their counterparts in artificial metasurfaces.Such plasmon polaritons are rare,but experimentally revealed recently in WTe_(2)van der Waals thin films.Different from phonon polaritons,hyperbolic plasmon polaritons originate from the interplay of free carrier Drude response and interband transitions,which promise good intrinsic tunability.However,tunable in-plane hyperbolic plasmon polariton and its optical topological transition of the isofrequency contours to the elliptic topology in a natural material have not been realized.Here we demonstrate the tuning of the optical topological transition through Mo doping and temperature.The optical topological transition energy is tuned over a wide range,with frequencies ranging from 429 cm^(−1)(23.3 microns)for pure WTe_(2)to 270 cm^(−1)(37.0 microns)at the 50%Mo-doping level at 10 K.Moreover,the temperature-induced blueshift of the optical topological transition energy is also revealed,enabling active and reversible tuning.Surprisingly,the localized surface plasmon resonance in skew ribbons shows unusual polarization dependence,accurately manifesting its topology,which renders a reliable means to track the topology with far-field techniques.Our results open an avenue for reconfigurable photonic devices capable of plasmon polariton steering,such as canaling,focusing,and routing,and pave the way for low-symmetry plasmonic nanophotonics based on anisotropic natural materials.
基金supported by the National Natural Science Foundation of China(11674157,51372112 and 11574133)the National Key Research and Development Plan(2016YFA0300404)the National Basic Research Program of China(2015CB921202)
文摘Dirac nodal-line semimetals with the linear bands crossing along a line or loop, represent a new topological state of matter. Here, by carrying out magnetotransport measurements and performing first-principle calculations, we demonstrate that such a state has been realized in high-quality single crystals of SrAs_3.We obtain the nontrivial ∏ Berry phase by analysing the Shubnikov-de Haas quantum oscillations. We also observe a robust negative longitudinal magnetoresistance induced by the chiral anomaly.Accompanying first-principles calculations identifies that a single hole pocket enclosing the loop nodes is responsible for these observations.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0306800)the National Natural Science Foundation of China(Grant Nos.11714154,11790311,and 11774151)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.020414380110)the Program for High-Level Entrepreneurial and Innovative Talents Introduction,Jiangsu Province
文摘Performing angle-resolved photoemission spectroscopy(ARPES) and theoretical calculations for ZrSnTe, we find a nodal line in the kx-ky plane with a tiny gap and two nodal lines without gaps along the kzdirection. The constant energy contours are plotted in the kx-ky plane at a photon energy of 30 e V to examine the gapping feature of the nodal line. In addition, we depict the band dispersions along the Γ-M and Γ-X directions from the ARPES images at photon energies ranging from 24 to 40 e V. The kz mapping confirms the presence of stable Dirac points with obvious kzdependences along the M-A and X-R directions. In this paper, we report the two types of nodal lines associated with the theoretical local-density approximation calculations, broadening the horizons of nodal-line semimetal research.
文摘Unsaturated magnetoresistance (MR) has been reported in type-II Weyl semimetal WTe2, manifested as a perfect compensation of opposite carriers. We report linear MR (LMR) in WTe2 crystals, the onset of which was identified by constructing the MR mobility spectra for weak fields. The LMR further increased and became dominant for fields stronger than 20 T, while the parabolic MR gradually decayed. The LMR was also observed in high-pressure conditions.
基金This study was funded by the National Natural Science Foundation of China(No.81900984,81870747 and 81860194)the Beijing Municipal Natural Science Foundation(No.7182184).
文摘Cleft lip and/or palate(CL/P)is a most common craniofacial birth defect which has multifactorial etiology.In our study,we aimed to discover the underlying etiological gene variation in a Chinese family diagnosed as non-syndromic CL/P(NSCL/P).The blood sample of the proband and her parents were detected by whole exome sequencing.The Mendelian inheritance pattern,allele frequency,variation location,function analysis and literature search were applied to filtrate and screen the mutation.Besides,the candidates were confirmed by Sanger sequencing.We meanwhile explored the conservative analysis and protein homology simulation.As a result,a start-lost mutation c.1A>GAtg/Gtg in the Frizzled-6(FZD6)gene predicting p.Met1 was detected.The variation has not been reported before and was predicted to be harmful.The alteration caused missing of two starting amino acids that are evolutionarily conserved for FZD6 protein.Moreover,the specific structure of the mutant protein obviously changed according to the results of the homologous model.In conclusion,the results suggest c.1A>GAtg/Gtg in the FZD6(NM_001164616)might be the genetic etiology for non-syndromic CL/P in this pedigree.Furthermore,this finding provided new etiologic information,supplementing the evidence that FZD6 is a strong potential gene for CL/P.