The search of quantum spin liquid(QSL),an exotic magnetic state with strongly fluctuating and highly entangled spins down to zero temperature,is a main theme in current condensed matter physics.However,there is no smo...The search of quantum spin liquid(QSL),an exotic magnetic state with strongly fluctuating and highly entangled spins down to zero temperature,is a main theme in current condensed matter physics.However,there is no smoking gun evidence for deconfined spinons in any QSL candidate so far.The disorders and competing exchange interactions may prevent the formation of an ideal QSL state on frustrated spin lattices.Here we report comprehensive and systematic measurements of the magnetic susceptibility,ultralow-temperature specific heat,muon spin relaxation(μSR),nuclear magnetic resonance(NMR),and thermal conductivity for NaYbSe2 single crystals,in which Yb3+ions with effective spin-1/2 form a perfect triangular lattice.All these complementary techniques find no evidence of long-range magnetic order down to their respective base temperatures.Instead,specific heat,μSR,and NMR measurements suggest the coexistence of quasi-static and dynamic spins in NaYbSe2.The scattering from these quasi-static spins may cause the absence of magnetic thermal conductivity.Thus,we propose a scenario of fluctuating ferrimagnetic droplets immersed in a sea of QSL.This may be quite common on the way pursuing an ideal QSL,and provides a brand new platform to study how a QSL state survives impurities and coexists with other magnetically ordered states.展开更多
We construct a class of exactly solvable generalized Kitaev spin-1/2 models in arbitrary dimensions, which is beyond the category of quantum compass models. The Jordan-Wigner transformation is employed to prove the ex...We construct a class of exactly solvable generalized Kitaev spin-1/2 models in arbitrary dimensions, which is beyond the category of quantum compass models. The Jordan-Wigner transformation is employed to prove the exact solvability. An exactly solvable quantum spin-1/2 model can be mapped to a gas of free Majorana fermions coupled to static Z2 gauge fields. We classify these exactly solvable models according to their parent models. Any model belonging to this class can be generated by one of the parent models. For illustration, a two dimensional(2D) tetragon-octagon model and a three dimensional(3D) xy bond model are studied.展开更多
基金National Key R&D Program of China(Grant No.2022YFA1402203)National Natural Science Foundation of China of China(Grant No.12034004,No.11774061,and No.11774306)+2 种基金Shanghai Municipal Science and Technology(Major Project Grant No.2019SHZDZX01,No.20ZR1405300,and No.23ZR1404500)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB28000000)Innovation program for Quantum Science and Technology(Grant No.2021ZD0302500).
文摘The search of quantum spin liquid(QSL),an exotic magnetic state with strongly fluctuating and highly entangled spins down to zero temperature,is a main theme in current condensed matter physics.However,there is no smoking gun evidence for deconfined spinons in any QSL candidate so far.The disorders and competing exchange interactions may prevent the formation of an ideal QSL state on frustrated spin lattices.Here we report comprehensive and systematic measurements of the magnetic susceptibility,ultralow-temperature specific heat,muon spin relaxation(μSR),nuclear magnetic resonance(NMR),and thermal conductivity for NaYbSe2 single crystals,in which Yb3+ions with effective spin-1/2 form a perfect triangular lattice.All these complementary techniques find no evidence of long-range magnetic order down to their respective base temperatures.Instead,specific heat,μSR,and NMR measurements suggest the coexistence of quasi-static and dynamic spins in NaYbSe2.The scattering from these quasi-static spins may cause the absence of magnetic thermal conductivity.Thus,we propose a scenario of fluctuating ferrimagnetic droplets immersed in a sea of QSL.This may be quite common on the way pursuing an ideal QSL,and provides a brand new platform to study how a QSL state survives impurities and coexists with other magnetically ordered states.
基金the China Postdoctoral Science Foundation of China(Grant No.2017M620880)the National Natural Science Foundation of China(Grant No.1184700424)+7 种基金the National Key Research and Development Program of China(Grant No.2016YFA0300202)the National Basic Research Program of China(Grant No.2014CB921201)the National Natural Science Foundation of Chino(Grant No.11774306)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB08-4)the Fundamental Research Funds for the Central Universities in Chinathe National Natural Science Foundation of China(Grant No.11674278)the National Basic Research Program of China(Grant No.2014CB921203)the CAS Center for Excellence in Topological Quantum Computation.
文摘We construct a class of exactly solvable generalized Kitaev spin-1/2 models in arbitrary dimensions, which is beyond the category of quantum compass models. The Jordan-Wigner transformation is employed to prove the exact solvability. An exactly solvable quantum spin-1/2 model can be mapped to a gas of free Majorana fermions coupled to static Z2 gauge fields. We classify these exactly solvable models according to their parent models. Any model belonging to this class can be generated by one of the parent models. For illustration, a two dimensional(2D) tetragon-octagon model and a three dimensional(3D) xy bond model are studied.