The honeycomb magnet Na_(3)Co_(2)SbO_(6)recently emerged as a promising candidate for realizing Kitaev quantum spin liquid with relatively low levels of structural disorder.While the precise spin Hamiltonian remains c...The honeycomb magnet Na_(3)Co_(2)SbO_(6)recently emerged as a promising candidate for realizing Kitaev quantum spin liquid with relatively low levels of structural disorder.While the precise spin Hamiltonian remains controversial,the potential existence of a quantum spin liquid or other novel quantum magnetic phases continues to stimulate investigation.Here,we study the temperature and magnetic field-dependent spin excitations of Na_(3)Co_(2)SbO_(6)on a twin-free single crystal using magneto-terahertz(THz)spectroscopy,focusing on magnetic anisotropy and field-induced unusual phases.We observe a low-energy continuum excitation above T_(N)and a 0.5 THz(2 meV)spin wave excitation in magnetic order under zero field.Upon applying an in-plane magnetic field,the spin waves transform to a magnetic continuum over an intermediate field range,above which the system enters a spin-polarized state.Crucially,the spin excitation spectra reveal striking anisotropy between the a and b crystallographic axes,demanding description by a strongly anisotropic spin model.These findings establish Na_(3)Co_(2)SbO_(6)as a model system for investigating field-tunable quantum magnetism and potential spin liquid behavior in highly anisotropic systems.展开更多
A systematic theory on the appropriate spin operators for the relativistic states is developed. For a massive relativistic particle with arbitrary nonzero spin, the spin operator should be replaced with the relativist...A systematic theory on the appropriate spin operators for the relativistic states is developed. For a massive relativistic particle with arbitrary nonzero spin, the spin operator should be replaced with the relativistic one, which is called in this paper as moving spin. Further the concept of moving spin is discussed in the quantum field theory. A new operator, field quanta spin is defined and in terms of the generators of Poincaré group the moving spin of field system is constructed. It is shown that, in virtue of the two operators, problems in quantum field concerned spin can be neatly settled.展开更多
Spintronics involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. The fascinating spin-resolved properties of graphene motivate numerous researchers to study spintron...Spintronics involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. The fascinating spin-resolved properties of graphene motivate numerous researchers to study spintronics in graphene and other two-dimensional(2D) materials. Silicene, the silicon analog of graphene, is considered to be a promising material for spintronics. Here, we present a review of theoretical advances with regard to spin-dependent properties, including the electric field- and exchange field-tunable topological properties of silicene and the corresponding spintronic device simulations.展开更多
Within the framework of the effective-field theory with self-spin correlations and the differential operator technique, the ground state magnetizations of the biaxial crystal field spin system on the honeycomb lattice...Within the framework of the effective-field theory with self-spin correlations and the differential operator technique, the ground state magnetizations of the biaxial crystal field spin system on the honeycomb lattices have been studied. The influences of the biaxial crystal field on the magnetization in the ground state have been investigated in detail.展开更多
In the new framework of gravitational quantum field theory(GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D 93(2016) 024012-1, we make a perturbative expansion for the full action in a background...In the new framework of gravitational quantum field theory(GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D 93(2016) 024012-1, we make a perturbative expansion for the full action in a background field which accounts for the early inflationary universe. We decompose the bicovariant vector fields of gravifield and spin gauge field with Lorentz and spin symmetries SO(1,3) and SP(1,3) in biframe spacetime into SO(3) representations for deriving the propagators of the basic quantum fields and extract their interaction terms. The leading order Feynman rules are presented. A tree-level 2 to 2 scattering amplitude of the Dirac fermions, through a gravifield and a spin gauge field, is calculated and compared to the Born approximation of the potential. It is shown that the Newton's gravitational law in the early universe is modified due to the background field. The spin dependence of the gravitational potential is demonstrated.展开更多
We investigate spin squeezing effects of trapped ions in an off-resonance optical potential system using the arbitrary range spin spin interaction and transverse field model. The collective spin noises at any time are...We investigate spin squeezing effects of trapped ions in an off-resonance optical potential system using the arbitrary range spin spin interaction and transverse field model. The collective spin noises at any time are analyzed exactly. The general expression of spin squeezing factor is presented for arbitrary-range spin interaction. For the nearest-neighbor and next-nearest neighbor spin interaction model, the analytic solutions are reduced from the general expressions. It is shown that the maximum spin squeezing is enhanced for the general arbitrary-range spin interaction compared with the nearest-neighbor interaction model as the long-range interaction with arbitrary sites enforces stronger correlation.展开更多
We study theoretically the influence of spin-orbit coupling induced by in-plane external electric field on the intrinsic spin-Hall effect in a two-dimensional electron gas with Rashba spin-orbit coupling. We show that...We study theoretically the influence of spin-orbit coupling induced by in-plane external electric field on the intrinsic spin-Hall effect in a two-dimensional electron gas with Rashba spin-orbit coupling. We show that, after such an influence is taken into account, the static intrinsic spin-Hall effect can be stabilized in a disordered Rashba twodimensional electron gas, and the static intrinsic spin-Hall conductivity shall exhibit some interesting characteristics as conceived in some original theoretical proposals.展开更多
The maximum entangled number state （NOON state） can improve the sensitivity of physical quantity measure- ment to the Heisenberg limit 1/N. In this work, the magnetic field measurement based on the individual solid ...The maximum entangled number state （NOON state） can improve the sensitivity of physical quantity measure- ment to the Heisenberg limit 1/N. In this work, the magnetic field measurement based on the individual solid spin NOON state is investigated. Based on the tunable effective coupling coefficient, we propose a generation scheme of the three-spin NOON state, i.e, the Creenberger-Horne-Zeilinger （CHZ） state, and discussed the mea- surement resolution reduction due to decoherence. It is unnecessary to entangle spins as many as possible when decoherence exists. In practice, defect spins in diamond and alp donors with long coherence time can be applied with current techniques in the nano-scaled high resolution magnetic measurement.展开更多
This paper is only an outline for the observed fact of twits-up of matter,super-low temperature and modern discovered appearance of thing of twists-ups of matters and irregular spin flow for electrochemistry,photochem...This paper is only an outline for the observed fact of twits-up of matter,super-low temperature and modern discovered appearance of thing of twists-ups of matters and irregular spin flow for electrochemistry,photochemistry in experiment,and involved problems of transform of spin flow and the process of blown-up and transformation for deformed spin flow,spin field,cold after death,heat after death,yet.The understand of spin of matter construction involved the crux of that questions are left over by contemporary science,and it has hinted new trends of science develop and revolution of systems for sense,theory and method,too.展开更多
As is well-known, it is very difficult to solve wave equations in curved space-time. In this paper,we find that wave equations describing massless fields of the spins s≤2 in accelerating KerrNewman black holes can be...As is well-known, it is very difficult to solve wave equations in curved space-time. In this paper,we find that wave equations describing massless fields of the spins s≤2 in accelerating KerrNewman black holes can be written as a compact master equation. The master equation can be separated to radial and angular equations, and both can be transformed to Heun’s equation,which shows that there are analytic solutions for all the wave equations of massless spin fields.The results not only demonstrate that it is possible to study the similarity between waves of gravitational and other massless spin fields, but also it can deal with other astrophysical applications, such as quasinormal modes, scattering, stability, etc. In addition, we also derive approximate solutions of the radial equation.展开更多
Large superconducting Fe Se crystals of（001） orientation have been prepared via a hydrothermal ion release/introduction route for the first time. The hydrothermally derived Fe Se crystals are up to 10 mm×5 mm&#...Large superconducting Fe Se crystals of（001） orientation have been prepared via a hydrothermal ion release/introduction route for the first time. The hydrothermally derived Fe Se crystals are up to 10 mm×5 mm×0.3 mm in dimension. The pure tetragonal FeSe phase has been confirmed by x-ray diffraction（XRD） and the composition determined by both inductively coupled plasma atomic emission spectroscopy（ICP-AES） and energy dispersive x-ray spectroscopy（EDX）. The superconducting transition of the Fe Se samples has been characterized by magnetic and transport measurements. The zero-temperature upper critical field H（c2） is calculated to be 13.2–16.7 T from a two-band model. The normal-state cooperative paramagnetism is found to be predominated by strong spin frustrations below the characteristic temperature T（sn）, where the Ising spin nematicity has been discerned in the FeSe superconductor crystals as reported elsewhere.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.12488201,12250008,12474138,and 12274004)the National Key Research and Development Program of China(Grant No.2021YFA1401901,2022YFA1403901,2023YFA1406002,and 2024YFA1408301)。
文摘The honeycomb magnet Na_(3)Co_(2)SbO_(6)recently emerged as a promising candidate for realizing Kitaev quantum spin liquid with relatively low levels of structural disorder.While the precise spin Hamiltonian remains controversial,the potential existence of a quantum spin liquid or other novel quantum magnetic phases continues to stimulate investigation.Here,we study the temperature and magnetic field-dependent spin excitations of Na_(3)Co_(2)SbO_(6)on a twin-free single crystal using magneto-terahertz(THz)spectroscopy,focusing on magnetic anisotropy and field-induced unusual phases.We observe a low-energy continuum excitation above T_(N)and a 0.5 THz(2 meV)spin wave excitation in magnetic order under zero field.Upon applying an in-plane magnetic field,the spin waves transform to a magnetic continuum over an intermediate field range,above which the system enters a spin-polarized state.Crucially,the spin excitation spectra reveal striking anisotropy between the a and b crystallographic axes,demanding description by a strongly anisotropic spin model.These findings establish Na_(3)Co_(2)SbO_(6)as a model system for investigating field-tunable quantum magnetism and potential spin liquid behavior in highly anisotropic systems.
基金国家自然科学基金，高等学校博士学科点专项科研项目，国家重点实验室基金，CTNP of LHIA National Lab of China，国家'211'工程建设项目，中国博士后科学基金
文摘A systematic theory on the appropriate spin operators for the relativistic states is developed. For a massive relativistic particle with arbitrary nonzero spin, the spin operator should be replaced with the relativistic one, which is called in this paper as moving spin. Further the concept of moving spin is discussed in the quantum field theory. A new operator, field quanta spin is defined and in terms of the generators of Poincaré group the moving spin of field system is constructed. It is shown that, in virtue of the two operators, problems in quantum field concerned spin can be neatly settled.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274016 and 11474012)the National Basic Research Program of China(Grant Nos.2013CB932604 and 2012CB619304)
文摘Spintronics involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. The fascinating spin-resolved properties of graphene motivate numerous researchers to study spintronics in graphene and other two-dimensional(2D) materials. Silicene, the silicon analog of graphene, is considered to be a promising material for spintronics. Here, we present a review of theoretical advances with regard to spin-dependent properties, including the electric field- and exchange field-tunable topological properties of silicene and the corresponding spintronic device simulations.
基金Project supported by the Natural Science Foundation of Liaoning province （Grant No 20041021） and the Scientific Research Foundation of the Educational Department of Liaoning province （Grant No 2004C006）.
文摘Within the framework of the effective-field theory with self-spin correlations and the differential operator technique, the ground state magnetizations of the biaxial crystal field spin system on the honeycomb lattices have been studied. The influences of the biaxial crystal field on the magnetization in the ground state have been investigated in detail.
基金Supported in part by the National Science Foundation of China(NSFC)under Grant Nos.11690022 and 11475237Strategic Priority Research Program of the Chinese Academy of Sciences(CAS), under Grant No.XDB23030100+1 种基金Key Research Program QYZDYSSWSYS007the CAS Center for Excellence in Particle Physics(CCEPP)
文摘In the new framework of gravitational quantum field theory(GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D 93(2016) 024012-1, we make a perturbative expansion for the full action in a background field which accounts for the early inflationary universe. We decompose the bicovariant vector fields of gravifield and spin gauge field with Lorentz and spin symmetries SO(1,3) and SP(1,3) in biframe spacetime into SO(3) representations for deriving the propagators of the basic quantum fields and extract their interaction terms. The leading order Feynman rules are presented. A tree-level 2 to 2 scattering amplitude of the Dirac fermions, through a gravifield and a spin gauge field, is calculated and compared to the Born approximation of the potential. It is shown that the Newton's gravitational law in the early universe is modified due to the background field. The spin dependence of the gravitational potential is demonstrated.
基金Supported by the National Natural Science Foundation of China under Grant No 51427801
文摘We investigate spin squeezing effects of trapped ions in an off-resonance optical potential system using the arbitrary range spin spin interaction and transverse field model. The collective spin noises at any time are analyzed exactly. The general expression of spin squeezing factor is presented for arbitrary-range spin interaction. For the nearest-neighbor and next-nearest neighbor spin interaction model, the analytic solutions are reduced from the general expressions. It is shown that the maximum spin squeezing is enhanced for the general arbitrary-range spin interaction compared with the nearest-neighbor interaction model as the long-range interaction with arbitrary sites enforces stronger correlation.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10874049)the State Key Program for Basic Research of China (Grant No. 2007CB925204)the Natural Science Foundation of Guangdong Province of China (GrantNo. 07005834)
文摘We study theoretically the influence of spin-orbit coupling induced by in-plane external electric field on the intrinsic spin-Hall effect in a two-dimensional electron gas with Rashba spin-orbit coupling. We show that, after such an influence is taken into account, the static intrinsic spin-Hall effect can be stabilized in a disordered Rashba twodimensional electron gas, and the static intrinsic spin-Hall conductivity shall exhibit some interesting characteristics as conceived in some original theoretical proposals.
基金Supported by the National Basic Research Program of China(No 2011CB921200)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences under Grant (No XDB01030200)+1 种基金the National Natural Science Foundation of China(No11374290)the Fundamental Research Funds for the Central Universities and the Foundation for Authors of National Excellent Doctoral Dissertation of China
文摘The maximum entangled number state （NOON state） can improve the sensitivity of physical quantity measure- ment to the Heisenberg limit 1/N. In this work, the magnetic field measurement based on the individual solid spin NOON state is investigated. Based on the tunable effective coupling coefficient, we propose a generation scheme of the three-spin NOON state, i.e, the Creenberger-Horne-Zeilinger （CHZ） state, and discussed the mea- surement resolution reduction due to decoherence. It is unnecessary to entangle spins as many as possible when decoherence exists. In practice, defect spins in diamond and alp donors with long coherence time can be applied with current techniques in the nano-scaled high resolution magnetic measurement.
基金Subsidized item of national nuture fund(Number of ratification:60172013)
文摘This paper is only an outline for the observed fact of twits-up of matter,super-low temperature and modern discovered appearance of thing of twists-ups of matters and irregular spin flow for electrochemistry,photochemistry in experiment,and involved problems of transform of spin flow and the process of blown-up and transformation for deformed spin flow,spin field,cold after death,heat after death,yet.The understand of spin of matter construction involved the crux of that questions are left over by contemporary science,and it has hinted new trends of science develop and revolution of systems for sense,theory and method,too.
基金supported by the National Natural Science Foundation of China under Grant No.11475148。
文摘As is well-known, it is very difficult to solve wave equations in curved space-time. In this paper,we find that wave equations describing massless fields of the spins s≤2 in accelerating KerrNewman black holes can be written as a compact master equation. The master equation can be separated to radial and angular equations, and both can be transformed to Heun’s equation,which shows that there are analytic solutions for all the wave equations of massless spin fields.The results not only demonstrate that it is possible to study the similarity between waves of gravitational and other massless spin fields, but also it can deal with other astrophysical applications, such as quasinormal modes, scattering, stability, etc. In addition, we also derive approximate solutions of the radial equation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574370,11274358,and 11190020)the National Basic Research Program of China(Grant No.2013CB921700)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB07020100)
文摘Large superconducting Fe Se crystals of（001） orientation have been prepared via a hydrothermal ion release/introduction route for the first time. The hydrothermally derived Fe Se crystals are up to 10 mm×5 mm×0.3 mm in dimension. The pure tetragonal FeSe phase has been confirmed by x-ray diffraction（XRD） and the composition determined by both inductively coupled plasma atomic emission spectroscopy（ICP-AES） and energy dispersive x-ray spectroscopy（EDX）. The superconducting transition of the Fe Se samples has been characterized by magnetic and transport measurements. The zero-temperature upper critical field H（c2） is calculated to be 13.2–16.7 T from a two-band model. The normal-state cooperative paramagnetism is found to be predominated by strong spin frustrations below the characteristic temperature T（sn）, where the Ising spin nematicity has been discerned in the FeSe superconductor crystals as reported elsewhere.
