An effective approach for optimizing the rotor contour for variable reluctance(VR)resolver is presented.Using this approach,the procedure for optimizing the rotor is divided into two parts:the establishment of initial...An effective approach for optimizing the rotor contour for variable reluctance(VR)resolver is presented.Using this approach,the procedure for optimizing the rotor is divided into two parts:the establishment of initial shape curve,and then computation for the optimization.In order to simplify the process of the former,a shape function is constructed.And the latter is carried out by Taguchi optimization method and finite element method(FEM).An example of a 3-10 VR resolver is used to present the procedure of the optimization,and the testing results confirmed the effectivity of the approach.展开更多
The configuration of a brushless DC torque motor is introduced. According to the fundamental relation of the armature winding current and the air gap flux density, the ripple torque caused by the electrical errors of ...The configuration of a brushless DC torque motor is introduced. According to the fundamental relation of the armature winding current and the air gap flux density, the ripple torque caused by the electrical errors of a resolver is approached. And a polyphase multipole resolver is developed in the brushless DC torque motor. Finally, the experimental results are presented to illustrate the improvement of ripple torque in the brushless DC torque motor with the polyphase multipole resolver.展开更多
Fraction repetition(FR)codes are integral in distributed storage systems(DSS)with exact repair-by-transfer,while pliable fraction repetition codes are vital for DSSs in which both the per-node storage and repetition d...Fraction repetition(FR)codes are integral in distributed storage systems(DSS)with exact repair-by-transfer,while pliable fraction repetition codes are vital for DSSs in which both the per-node storage and repetition degree can easily be adjusted simultaneously.This paper introduces a new type of pliable FR codes,called absolute balanced pliable FR(ABPFR)codes,in which the access balancing in DSS is considered.Additionally,the equivalence between pliable FR codes and resolvable transversal packings in combinatorial design theory is presented.Then constructions of pliable FR codes and ABPFR codes based on resolvable transversal packings are presented.展开更多
In hypersonic boundary layers,the optimal disturbance is notably caused by normalmode instabilities,such as Mack second mode.However,recent experimental and numerical efforts have demonstrated the dominance of nonmoda...In hypersonic boundary layers,the optimal disturbance is notably caused by normalmode instabilities,such as Mack second mode.However,recent experimental and numerical efforts have demonstrated the dominance of nonmodal growth in hypersonic flows with the presence of moderate nose bluntness.In this study,resolvent analysis and parabolized stability equation analysis are performed to investigate the instabilities over a blunt-tip wedge.Main parameters include Mach number 5.9,unit Reynolds number 91.5×10~6/m,half wedge angle 5°,and nose radii ranging from 2.54 mm to 15.24 mm.Two novel growth patterns of travelling waves are identified to compete,whose nature is the intersection of the energy gain of optimal and sub-optimal disturbances.Pattern A with large spanwise wavelengths has the signature of slow energy amplification over a long distance which concentrates in the entropy layer.By contrast,pattern B with relatively small spanwise wavelengths presents rapid transient growth inside the boundary layer.A systematic study is performed on the growth/attenuation mechanism of disturbance patterns and the effects of wall temperature and nose radius.Wall cooling is found to be an alternative control strategy aimed at nonmodal instabilities.The receptivity to slow acoustic waves is considered when the effect of bluntness is studied.An estimated amplitude response favorably reproduces the reversal-like phenomenon.The lift-up/Orr mechanism analysis provides an explanation of energy growth for nonmodal responses.展开更多
Nonlinear energy transfer is represented through eddy viscosity and stochastic forcing within the framework of resolvent analysis.Previous investigations estimate the contribution of eddy-viscosity-enhanced resolvent ...Nonlinear energy transfer is represented through eddy viscosity and stochastic forcing within the framework of resolvent analysis.Previous investigations estimate the contribution of eddy-viscosity-enhanced resolvent opera-tor to nonlinear energy transfer.The present article estimates the contribution of stochastic forcing to nonlinear energy transfer and demonstrates that the contribution of stochastic forcing cannot be ignored.These results are achieved by numerically comparing the eddy-viscosity-enhanced resolvent operator and stochastic forcing with nonlinear energy transfer in turbulent channel flows.Furthermore,the numerical results indicate that composite resolvent operators can improve the prediction of nonlinear energy transfer.展开更多
Granulomatosis with polyangiitis(GPA)poses significant therapeutic challenges due to its susceptibility to concurrent infections and frequent relapses.Professor SHI Zaixiang proposed the therapeutic theory of lifting ...Granulomatosis with polyangiitis(GPA)poses significant therapeutic challenges due to its susceptibility to concurrent infections and frequent relapses.Professor SHI Zaixiang proposed the therapeutic theory of lifting depression and removing blood stasis,resolving phlegm and dispelling nodulation for GPA management.He identified the core pathogenesis as“Qi collapse with collateral obstruction and phlegm-stasis intermingling”,establishing the treatment principle of comprehensive intervention through ascending ancestral Qi,activating blood circulation,and resolving phlegm-stasis nodules.In clinical practice,Professor SHI emphasizes maintaining immune homeostasis with herbal medicine to enhance efficiency,while dynamically balancing Qi,blood,Yin,and Yang.Notably,he highlights the critical role of emotional factors in autoimmune disease progression.A representative case was provided to elucidate his clinical reasoning in GPA treatment.展开更多
In this paper,we study the nonlinear stability problem for the two-dimensional Boussinesq system around the Couette flow in a finite channel with Navier-slip boundary condition for the velocity and Dirichlet boundary ...In this paper,we study the nonlinear stability problem for the two-dimensional Boussinesq system around the Couette flow in a finite channel with Navier-slip boundary condition for the velocity and Dirichlet boundary condition for the temperature with small viscosityνand small thermal diffusionμ.We establish that if the initial perturbation velocity and initial perturbation temperature satisfy ||u_(0)||H^(2)≤ε_(0) min{μ,ν}1/2, and ||θ_(0)||H^(1)+|||D_(x)|^(1/3)θ_(0)||H^(1)+|||D_(x)|^(1/3)θ_(0)||_(H^(1))≤εi min{μ,ν}^(5/6),for some smallε0 andε1 independent ofμ,ν,then the solution of the two-dimensional NavierStokes Boussinesq system does not transition away from the Couette flow for any time.展开更多
In this article,we study the approximate controllability of neutral partial differential equations with Hilfer fractional derivative and not instantaneous impulses effects.By using the Sadovskii's fixed point theo...In this article,we study the approximate controllability of neutral partial differential equations with Hilfer fractional derivative and not instantaneous impulses effects.By using the Sadovskii's fixed point theorem,fractional calculus and resolvent operator functions,we prove the approximate controllability of the considered system.展开更多
Recent advances in spatially resolved transcriptomics(SRT)have provided new opportunities for characterizing spatial structures of various tissues.Graph-based geometric deep learning has gained widespread adoption for...Recent advances in spatially resolved transcriptomics(SRT)have provided new opportunities for characterizing spatial structures of various tissues.Graph-based geometric deep learning has gained widespread adoption for spatial domain identification tasks.Currently,most methods define adjacency relation between cells or spots by their spatial distance in SRT data,which overlooks key biological interactions like gene expression similarities,and leads to inaccuracies in spatial domain identification.To tackle this challenge,we propose a novel method,SpaGRA(https://github.com/sunxue-yy/SpaGRA),for automatic multi-relationship construction based on graph augmentation.SpaGRA uses spatial distance as prior knowledge and dynamically adjusts edge weights with multi-head graph attention networks(GATs).This helps SpaGRA to uncover diverse node relationships and enhance message passing in geometric contrastive learning.Additionally,SpaGRA uses these multi-view relationships to construct negative samples,addressing sampling bias posed by random selection.Experimental results show that SpaGRA presents superior domain identification performance on multiple datasets generated from different protocols.Using SpaGRA,we analyze the functional regions in the mouse hypothalamus,identify key genes related to heart development in mouse embryos,and observe cancer-associated fibroblasts enveloping cancer cells in the latest Visium HD data.Overall,SpaGRA can effectively characterize spatial structures across diverse SRT datasets.展开更多
This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical sl...This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical slip trace analysis and electron backscatter diffraction.The studied regions covered a total of 1150 grains,in which 136 sets of slip traces were identified and analyzed in detail.The basalslip always dominated the deformation,whose frequencies decreased(from 81.0%to 62.5%)with increasing GS(from 10 to 85μm).The prismaticslip activity increased from 10.8%(10μm)to 27.5%(85μm),while that for pyramidal II<c+a>slip was almost constant.Critical resolved shear stress(CRSS)ratios were estimated based on the identified slip activity statistics,and then the Hall-Petch coefficients(k)of individual slip modes were calculated.The k value for prismaticslip(194 MPa·μm^(1/2))was lower than that for pyramidal II<c+a>slip(309 MPa·μm^(1/2)),which implies that pyramidal II<c+a>slip was more GS sensitive.Twinning activity exhibited a positive correlation with GS,though it remained limited partly due to the unfavorable loading direction.The macroscopic Hall-Petch relationship was divided into two regions,i.e.,the k value(753 MPa·μm^(1/2))for the coarse-grain region(30-85μm)was significantly larger than that(118 MPa·μm^(1/2))of the fine-grain region(10-30μm),which could be attributed to the transition of predominant deformation mechanisms from slip to slip combined twinning with increasing GS.This work provides detailed and quantitative experimental data of the GS effects on individual slip activities of Mg and provides new insights into the Hall-Petch relationship for individual slip modes.展开更多
Silicene,a silicon analog of graphene,holds promise for next-generation electronics due to its tunable bandgap and larger spin-orbit coupling.Despite extensive efforts to synthesize and characterize silicene on metal ...Silicene,a silicon analog of graphene,holds promise for next-generation electronics due to its tunable bandgap and larger spin-orbit coupling.Despite extensive efforts to synthesize and characterize silicene on metal substrates,bondresolved imaging of its atomic structure has remained elusive.Here,we report the fabrication and bond-resolved characterization of silicene on Au(111)substrate.Three silicene phases tuned by surface reconstruction and annealing temperatures are achieved.Using CO-terminated scanning tunneling microscopy(STM)tips,we resolve these silicene phases with atomic precision,determining their bond lengths,local strain,and geometric configurations.Furthermore,we correlate these structural features with their electronic properties,revealing the effect of strain and substrate interactions on the electronic properties of silicene.This work establishes silicene's intrinsic bonding topology and resolves longstanding controversies in silicene research.展开更多
Photocatalysts show broad application potential in clean energy conversion by utilizing solar energy for chemical transformations[1–3].However,single-component photocatalysts are severely limited in practical applica...Photocatalysts show broad application potential in clean energy conversion by utilizing solar energy for chemical transformations[1–3].However,single-component photocatalysts are severely limited in practical applications due to narrow light absorption ranges and high recombination rates of photogenerated carriers[4].S-scheme heterojunctions preserve optimal redox potentials,offering broad application prospects in solar energy conversion and environmental remediation[5,6].Since photocatalytic reactions occur predominantly at the material interface,a spatially resolved investigation of charge transfer is essential for understanding carrier dynamics at the nanoscale[7].In this context,the highlighted study employs Kelvin probe force microscopy(KPFM)to elucidate the real-space charge-transfer mechanisms in CdS/BiOBr S-scheme heterojunctions,providing direct and quantitative insight into interfacial charge behavior[8].展开更多
Altermagnets represent a newly discovered class of magnetically ordered materials.Among all the candidates,CrSb stands out due to its largest spin splitting energy and highest Néel temperature exceeding 700 K,mak...Altermagnets represent a newly discovered class of magnetically ordered materials.Among all the candidates,CrSb stands out due to its largest spin splitting energy and highest Néel temperature exceeding 700 K,making it promising for room-temperature spintronic applications.Here we have successfully grown high quality CrSb(100)thin film on GaAs(110)substrate by molecular beam epitaxy.Using angle-resolved photoemission spectroscopy,we successfully obtained the three-dimensional electronic structure of the thin film.Moreover,we observed the emergence of the altermagnetic splitting bands corresponding to the calculated results along the low symmetry pathsT-QandP-D.The bands near the Fermi level are only spin splitting bands along theP-Ddirection,with splitting energy reaching as high as 910 meV.This finding provides insights into the magnetic properties of CrSb thin films and paves the way for further studies on their electronic structure and potential applications in spintronics.展开更多
LiV_(2)O_(4)is a spinel-structured compound that stands out as the first known 3d-electron system exhibiting typical heavy fermion behavior.A central question is how such strong mass renormalization emerges in the abs...LiV_(2)O_(4)is a spinel-structured compound that stands out as the first known 3d-electron system exhibiting typical heavy fermion behavior.A central question is how such strong mass renormalization emerges in the absence of f-electrons.In this work,we investigate the three-dimensional electronic structure of LiV_(2)O_(4)thin films using angle-resolved photoemission spectroscopy.We identify that an electron-like flat band is derived from a_(1g)orbitals,along with a highly dispersive e′_(g)band strongly coupled with phonons.The overall agreement with dynamical mean-field theory calculations highlights the essential role of inter-orbital Hund’s coupling in reducing the a_(1g)bandwidth to 25 meV,approaching a Mott state.Notably,we find that heavy-fermion behavior arises from additional renormalization at the a_(1g)band near the Fermi level,likely driven by many-body interactions at energy scales down to a few meV and potentially linked to geometric frustration inherent to the spinel lattice.These results provide crucial insights into the origin of the heavy fermion behavior in 3d-electron systems.展开更多
文摘An effective approach for optimizing the rotor contour for variable reluctance(VR)resolver is presented.Using this approach,the procedure for optimizing the rotor is divided into two parts:the establishment of initial shape curve,and then computation for the optimization.In order to simplify the process of the former,a shape function is constructed.And the latter is carried out by Taguchi optimization method and finite element method(FEM).An example of a 3-10 VR resolver is used to present the procedure of the optimization,and the testing results confirmed the effectivity of the approach.
文摘The configuration of a brushless DC torque motor is introduced. According to the fundamental relation of the armature winding current and the air gap flux density, the ripple torque caused by the electrical errors of a resolver is approached. And a polyphase multipole resolver is developed in the brushless DC torque motor. Finally, the experimental results are presented to illustrate the improvement of ripple torque in the brushless DC torque motor with the polyphase multipole resolver.
基金Supported in part by the National Key R&D Program of China(No.2020YFA0712300)NSFC(No.61872353)。
文摘Fraction repetition(FR)codes are integral in distributed storage systems(DSS)with exact repair-by-transfer,while pliable fraction repetition codes are vital for DSSs in which both the per-node storage and repetition degree can easily be adjusted simultaneously.This paper introduces a new type of pliable FR codes,called absolute balanced pliable FR(ABPFR)codes,in which the access balancing in DSS is considered.Additionally,the equivalence between pliable FR codes and resolvable transversal packings in combinatorial design theory is presented.Then constructions of pliable FR codes and ABPFR codes based on resolvable transversal packings are presented.
基金supported by the Hong Kong Research Grants Council(Nos.15216621,15204322,25203721)the National Natural Science Foundation of China(No.12102377)。
文摘In hypersonic boundary layers,the optimal disturbance is notably caused by normalmode instabilities,such as Mack second mode.However,recent experimental and numerical efforts have demonstrated the dominance of nonmodal growth in hypersonic flows with the presence of moderate nose bluntness.In this study,resolvent analysis and parabolized stability equation analysis are performed to investigate the instabilities over a blunt-tip wedge.Main parameters include Mach number 5.9,unit Reynolds number 91.5×10~6/m,half wedge angle 5°,and nose radii ranging from 2.54 mm to 15.24 mm.Two novel growth patterns of travelling waves are identified to compete,whose nature is the intersection of the energy gain of optimal and sub-optimal disturbances.Pattern A with large spanwise wavelengths has the signature of slow energy amplification over a long distance which concentrates in the entropy layer.By contrast,pattern B with relatively small spanwise wavelengths presents rapid transient growth inside the boundary layer.A systematic study is performed on the growth/attenuation mechanism of disturbance patterns and the effects of wall temperature and nose radius.Wall cooling is found to be an alternative control strategy aimed at nonmodal instabilities.The receptivity to slow acoustic waves is considered when the effect of bluntness is studied.An estimated amplitude response favorably reproduces the reversal-like phenomenon.The lift-up/Orr mechanism analysis provides an explanation of energy growth for nonmodal responses.
基金supported by the National Natural Science Foundation of China(NSFC)Basic Science Center Program for Multiscale Problems in Nonlinear Mechanics(Grant No.11988102).
文摘Nonlinear energy transfer is represented through eddy viscosity and stochastic forcing within the framework of resolvent analysis.Previous investigations estimate the contribution of eddy-viscosity-enhanced resolvent opera-tor to nonlinear energy transfer.The present article estimates the contribution of stochastic forcing to nonlinear energy transfer and demonstrates that the contribution of stochastic forcing cannot be ignored.These results are achieved by numerically comparing the eddy-viscosity-enhanced resolvent operator and stochastic forcing with nonlinear energy transfer in turbulent channel flows.Furthermore,the numerical results indicate that composite resolvent operators can improve the prediction of nonlinear energy transfer.
基金supported by the Seventh Batch of National Academic Experience Inheritance Project for Senior TCM Experts from the National Administration of Traditional Chinese Medicine(No.GZYRJS[2022]76)the Sixth Batch of Beijing Municipal Academic Experience Inheritance Project for TCM Experts from Beijing Administration of Traditional Chinese Medicine(No.JZYKZ[2019]139).
文摘Granulomatosis with polyangiitis(GPA)poses significant therapeutic challenges due to its susceptibility to concurrent infections and frequent relapses.Professor SHI Zaixiang proposed the therapeutic theory of lifting depression and removing blood stasis,resolving phlegm and dispelling nodulation for GPA management.He identified the core pathogenesis as“Qi collapse with collateral obstruction and phlegm-stasis intermingling”,establishing the treatment principle of comprehensive intervention through ascending ancestral Qi,activating blood circulation,and resolving phlegm-stasis nodules.In clinical practice,Professor SHI emphasizes maintaining immune homeostasis with herbal medicine to enhance efficiency,while dynamically balancing Qi,blood,Yin,and Yang.Notably,he highlights the critical role of emotional factors in autoimmune disease progression.A representative case was provided to elucidate his clinical reasoning in GPA treatment.
文摘In this paper,we study the nonlinear stability problem for the two-dimensional Boussinesq system around the Couette flow in a finite channel with Navier-slip boundary condition for the velocity and Dirichlet boundary condition for the temperature with small viscosityνand small thermal diffusionμ.We establish that if the initial perturbation velocity and initial perturbation temperature satisfy ||u_(0)||H^(2)≤ε_(0) min{μ,ν}1/2, and ||θ_(0)||H^(1)+|||D_(x)|^(1/3)θ_(0)||H^(1)+|||D_(x)|^(1/3)θ_(0)||_(H^(1))≤εi min{μ,ν}^(5/6),for some smallε0 andε1 independent ofμ,ν,then the solution of the two-dimensional NavierStokes Boussinesq system does not transition away from the Couette flow for any time.
基金Supported by Shandong University of Finance and Economics 2023 International Collaborative Projectsthe National Natural Science Foundation of China(Grant No.62073190)。
文摘In this article,we study the approximate controllability of neutral partial differential equations with Hilfer fractional derivative and not instantaneous impulses effects.By using the Sadovskii's fixed point theorem,fractional calculus and resolvent operator functions,we prove the approximate controllability of the considered system.
基金supported by the National Natural Science Foundation of China(Nos.62303271,U1806202,62103397)the Natural Science Foundation of Shandong Province(ZR2023QF081)Funding for open access charge:the National Natural Science Foundation of China(Nos.62303271,U1806202).
文摘Recent advances in spatially resolved transcriptomics(SRT)have provided new opportunities for characterizing spatial structures of various tissues.Graph-based geometric deep learning has gained widespread adoption for spatial domain identification tasks.Currently,most methods define adjacency relation between cells or spots by their spatial distance in SRT data,which overlooks key biological interactions like gene expression similarities,and leads to inaccuracies in spatial domain identification.To tackle this challenge,we propose a novel method,SpaGRA(https://github.com/sunxue-yy/SpaGRA),for automatic multi-relationship construction based on graph augmentation.SpaGRA uses spatial distance as prior knowledge and dynamically adjusts edge weights with multi-head graph attention networks(GATs).This helps SpaGRA to uncover diverse node relationships and enhance message passing in geometric contrastive learning.Additionally,SpaGRA uses these multi-view relationships to construct negative samples,addressing sampling bias posed by random selection.Experimental results show that SpaGRA presents superior domain identification performance on multiple datasets generated from different protocols.Using SpaGRA,we analyze the functional regions in the mouse hypothalamus,identify key genes related to heart development in mouse embryos,and observe cancer-associated fibroblasts enveloping cancer cells in the latest Visium HD data.Overall,SpaGRA can effectively characterize spatial structures across diverse SRT datasets.
基金supported by the National Natural Science Foundation of China(No.52171125)the Sichuan Science and Technology Program(No.2024NSFSC0193).
文摘This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical slip trace analysis and electron backscatter diffraction.The studied regions covered a total of 1150 grains,in which 136 sets of slip traces were identified and analyzed in detail.The basalslip always dominated the deformation,whose frequencies decreased(from 81.0%to 62.5%)with increasing GS(from 10 to 85μm).The prismaticslip activity increased from 10.8%(10μm)to 27.5%(85μm),while that for pyramidal II<c+a>slip was almost constant.Critical resolved shear stress(CRSS)ratios were estimated based on the identified slip activity statistics,and then the Hall-Petch coefficients(k)of individual slip modes were calculated.The k value for prismaticslip(194 MPa·μm^(1/2))was lower than that for pyramidal II<c+a>slip(309 MPa·μm^(1/2)),which implies that pyramidal II<c+a>slip was more GS sensitive.Twinning activity exhibited a positive correlation with GS,though it remained limited partly due to the unfavorable loading direction.The macroscopic Hall-Petch relationship was divided into two regions,i.e.,the k value(753 MPa·μm^(1/2))for the coarse-grain region(30-85μm)was significantly larger than that(118 MPa·μm^(1/2))of the fine-grain region(10-30μm),which could be attributed to the transition of predominant deformation mechanisms from slip to slip combined twinning with increasing GS.This work provides detailed and quantitative experimental data of the GS effects on individual slip activities of Mg and provides new insights into the Hall-Petch relationship for individual slip modes.
基金Project supported by the National Natural Science Foundation of China(Grant No.12474181)the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2021B0301030002 and 2024A1515010656)the Guangdong Science and Technology Project(Grant No.2021QN02X859)。
文摘Silicene,a silicon analog of graphene,holds promise for next-generation electronics due to its tunable bandgap and larger spin-orbit coupling.Despite extensive efforts to synthesize and characterize silicene on metal substrates,bondresolved imaging of its atomic structure has remained elusive.Here,we report the fabrication and bond-resolved characterization of silicene on Au(111)substrate.Three silicene phases tuned by surface reconstruction and annealing temperatures are achieved.Using CO-terminated scanning tunneling microscopy(STM)tips,we resolve these silicene phases with atomic precision,determining their bond lengths,local strain,and geometric configurations.Furthermore,we correlate these structural features with their electronic properties,revealing the effect of strain and substrate interactions on the electronic properties of silicene.This work establishes silicene's intrinsic bonding topology and resolves longstanding controversies in silicene research.
文摘Photocatalysts show broad application potential in clean energy conversion by utilizing solar energy for chemical transformations[1–3].However,single-component photocatalysts are severely limited in practical applications due to narrow light absorption ranges and high recombination rates of photogenerated carriers[4].S-scheme heterojunctions preserve optimal redox potentials,offering broad application prospects in solar energy conversion and environmental remediation[5,6].Since photocatalytic reactions occur predominantly at the material interface,a spatially resolved investigation of charge transfer is essential for understanding carrier dynamics at the nanoscale[7].In this context,the highlighted study employs Kelvin probe force microscopy(KPFM)to elucidate the real-space charge-transfer mechanisms in CdS/BiOBr S-scheme heterojunctions,providing direct and quantitative insight into interfacial charge behavior[8].
基金supported by the National Key R&D Program of China[Grant No.2023YFA1406304(J J)]the National Natural Science Foundation of China[Grant No.12174362(J J)]+2 种基金the Innovation Program for Quantum Science and Technology[Grant No.2021ZD0302803(D L F)]the New Cornerstone Science Foundation(D L F)Beamline 03U of the Shanghai Synchrotron Radiation Facility,which is supported by ME2 project under contract No.11227902 from the National Natural Science Foundation of China。
文摘Altermagnets represent a newly discovered class of magnetically ordered materials.Among all the candidates,CrSb stands out due to its largest spin splitting energy and highest Néel temperature exceeding 700 K,making it promising for room-temperature spintronic applications.Here we have successfully grown high quality CrSb(100)thin film on GaAs(110)substrate by molecular beam epitaxy.Using angle-resolved photoemission spectroscopy,we successfully obtained the three-dimensional electronic structure of the thin film.Moreover,we observed the emergence of the altermagnetic splitting bands corresponding to the calculated results along the low symmetry pathsT-QandP-D.The bands near the Fermi level are only spin splitting bands along theP-Ddirection,with splitting energy reaching as high as 910 meV.This finding provides insights into the magnetic properties of CrSb thin films and paves the way for further studies on their electronic structure and potential applications in spintronics.
基金support of Dr.Z.T.Liu,Dr.Z.C.Jiang,Dr.Marta Zonno,and Dr.Sergey Gorovikovsupported in part by the National Key R&D Program of the MOST of China(Grant No.2023YFA1406300)+4 种基金the National Natural Science Foundation of China(Grant Nos.12274085,12422404,and 92477206)the New Cornerstone Science Foundation,the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302803)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)The ARPES measurements used Beamlines 09U and 03U of the SSRF and Beamline QMSC of Canadian Light sourcesupported by the ME2 project from the National Natural Science Foundation of China(Contract No.11227902).
文摘LiV_(2)O_(4)is a spinel-structured compound that stands out as the first known 3d-electron system exhibiting typical heavy fermion behavior.A central question is how such strong mass renormalization emerges in the absence of f-electrons.In this work,we investigate the three-dimensional electronic structure of LiV_(2)O_(4)thin films using angle-resolved photoemission spectroscopy.We identify that an electron-like flat band is derived from a_(1g)orbitals,along with a highly dispersive e′_(g)band strongly coupled with phonons.The overall agreement with dynamical mean-field theory calculations highlights the essential role of inter-orbital Hund’s coupling in reducing the a_(1g)bandwidth to 25 meV,approaching a Mott state.Notably,we find that heavy-fermion behavior arises from additional renormalization at the a_(1g)band near the Fermi level,likely driven by many-body interactions at energy scales down to a few meV and potentially linked to geometric frustration inherent to the spinel lattice.These results provide crucial insights into the origin of the heavy fermion behavior in 3d-electron systems.
