Quantum spin liquid represents an intriguing state where electron spins are highly entangled yet spin fluctuation persists even at 0 K.Recently,the hexaaluminates RMgAl_(11)O_(19)(R=rare earth)have been proposed to be...Quantum spin liquid represents an intriguing state where electron spins are highly entangled yet spin fluctuation persists even at 0 K.Recently,the hexaaluminates RMgAl_(11)O_(19)(R=rare earth)have been proposed to be a platform for realizing the quantum spin liquid state with dominant Ising anisotropic correlations.Here,we report detailed low-temperature magnetic susceptibility,muon spin relaxation,and thermodynamic studies on the CeMgAl_(11)O_(19) single crystal.Ising anisotropy is revealed by magnetic susceptibility measurements.Muon spin relaxation and ac susceptibility measurements rule out any long-range magnetic ordering or spin freezing down to 50 mK despite the onset of spin correlations below∼0.8 K.Instead,the spins keep fluctuating at a rate of 1.0(2)MHz at 50 mK.Specific heat results indicate a gapless excitation with a power-law dependence on temperature,C_(m)(T)∝Tα.The quasi-quadratic temperature dependence withα=2.28(4)in zero field and linear temperature dependence in 0.25 T support the possible realization of the U(1)Dirac quantum spin liquid state.展开更多
Magnetization,specific heat,and muon spin relaxation(μSR)experiments have been carried out on the Cr-based nitride superconductor La_(3)Cr_(10-x)N_(11),which exhibits a number of unconventional superconducting proper...Magnetization,specific heat,and muon spin relaxation(μSR)experiments have been carried out on the Cr-based nitride superconductor La_(3)Cr_(10-x)N_(11),which exhibits a number of unconventional superconducting properties.The susceptibilityχ(T)shows nearly perfect superconducting diamagnetism(4πχ(T=0)≈-1)and a remarkably high upper critical fieldμ_(0)Hc_(2)=11.2 T.The specific heat displays activated exponential behavior exp(-Δ0/kBT),together with a large and field-dependent residual Sommerfeld coefficient.Transverse-field muon spin relaxation(μSR)measurements suggest s+s-wave or p-wave pairing symmetry,ruling out single s-wave pairing.Zero-fieldμSR yields no statistically significant evidence for time reversal symmetry breaking(TRSB),and places an upper bound of 1.5(1.3)ms-1 on any TRSB-induced muon relaxation rate at T=0.Our results suggest that the unconventional superconductivity in Ln_(3)Cr_(10-x)N_(11),Ln=La and Pr,is mainly due to Cr 3d electrons and is similar in both compounds,whereas Pr 4f electrons are primarily responsible for the TRSB superconductivity observed in Pr_(3)Cr_(10-x)N_(11).展开更多
基金supported by the Guangdong Basic and Applied Basic Research Foundation (Grant No.2022B1515120020)the National Natural Science Foundation of China (Grant No.11874158)The μSR experiments were supported by MLF of J-PARC under a user program (Grant No.2023B0022)
文摘Quantum spin liquid represents an intriguing state where electron spins are highly entangled yet spin fluctuation persists even at 0 K.Recently,the hexaaluminates RMgAl_(11)O_(19)(R=rare earth)have been proposed to be a platform for realizing the quantum spin liquid state with dominant Ising anisotropic correlations.Here,we report detailed low-temperature magnetic susceptibility,muon spin relaxation,and thermodynamic studies on the CeMgAl_(11)O_(19) single crystal.Ising anisotropy is revealed by magnetic susceptibility measurements.Muon spin relaxation and ac susceptibility measurements rule out any long-range magnetic ordering or spin freezing down to 50 mK despite the onset of spin correlations below∼0.8 K.Instead,the spins keep fluctuating at a rate of 1.0(2)MHz at 50 mK.Specific heat results indicate a gapless excitation with a power-law dependence on temperature,C_(m)(T)∝Tα.The quasi-quadratic temperature dependence withα=2.28(4)in zero field and linear temperature dependence in 0.25 T support the possible realization of the U(1)Dirac quantum spin liquid state.
基金funded by the National Key Research and Development Program of China(Grant No.2022YFA1402203)the National Natural Science Foundations of China(Grant No.12174065)+1 种基金the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300104)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01).
文摘Magnetization,specific heat,and muon spin relaxation(μSR)experiments have been carried out on the Cr-based nitride superconductor La_(3)Cr_(10-x)N_(11),which exhibits a number of unconventional superconducting properties.The susceptibilityχ(T)shows nearly perfect superconducting diamagnetism(4πχ(T=0)≈-1)and a remarkably high upper critical fieldμ_(0)Hc_(2)=11.2 T.The specific heat displays activated exponential behavior exp(-Δ0/kBT),together with a large and field-dependent residual Sommerfeld coefficient.Transverse-field muon spin relaxation(μSR)measurements suggest s+s-wave or p-wave pairing symmetry,ruling out single s-wave pairing.Zero-fieldμSR yields no statistically significant evidence for time reversal symmetry breaking(TRSB),and places an upper bound of 1.5(1.3)ms-1 on any TRSB-induced muon relaxation rate at T=0.Our results suggest that the unconventional superconductivity in Ln_(3)Cr_(10-x)N_(11),Ln=La and Pr,is mainly due to Cr 3d electrons and is similar in both compounds,whereas Pr 4f electrons are primarily responsible for the TRSB superconductivity observed in Pr_(3)Cr_(10-x)N_(11).
