Van der Waals magnet VI_(3) demonstrates intriguing magnetic properties that render it great for use in various applications.However,its microscopic magnetic structure has not been determined yet.Here,we report neutro...Van der Waals magnet VI_(3) demonstrates intriguing magnetic properties that render it great for use in various applications.However,its microscopic magnetic structure has not been determined yet.Here,we report neutron diffraction and susceptibility measurements in VI_(3) that revealed a ferromagnetic order with the moment direction tilted from the c-axis by ~36° at 4 K.A spin reorientation accompanied by a structure distortion within the honeycomb plane is observed,before the magnetic order completely disappears at TC=50 K.The refined magnetic moment of ~1.3μB at 4 K is much lower than the fully ordered spin moment of 2μB/V^(3+),suggesting the presence of a considerable orbital moment antiparallel to the spin moment and strong spin-orbit coupling in VI_(3).This results in strong magnetoelastic interactions that make the magnetic properties of VI_(3) easily tunable via strain and pressure.展开更多
The discovery of pressure-induced superconductivity in helimagnets(CrAs,MnP)has attracted considerable interest in understanding the relationship between complex magnetism and unconventional superconductivity.However,...The discovery of pressure-induced superconductivity in helimagnets(CrAs,MnP)has attracted considerable interest in understanding the relationship between complex magnetism and unconventional superconductivity.However,the nature of the magnetism and magnetic interactions that drive the unusual double-helical magnetic order in these materials remains unclear.Here,we report neutron scattering measurements of magnetic excitations in CrAs single crystals at ambient pressure.Our experiments reveal well defined spin wave excitations up to about 150 meV with a pseudogap below 7 meV,which can be effectively described by the Heisenberg model with nearest neighbor exchange interactions.Most surprisingly,the spin excitations are largely quenched above the Néel temperature,in contrast to cuprates and iron pnictides where the spectral weight is mostly preserved in the paramagnetic state.Our results suggest that the helimagnetic order is driven by strongly frustrated exchange interactions,and that CrAs is at the verge of itinerant and correlation-induced localized states,which is therefore highly pressure-tunable and favorable for superconductivity.展开更多
基金Supported by the Innovation Program of Shanghai Municipal Education Commission(Grant No.2017-01-07-00-07-E00018)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+1 种基金the National Natural Science Foundation of China(Grant No.11874119)the support of U.S.DOE BES Early Career Award No.KC0402020 under Contract No.DE-AC05-00OR22725。
文摘Van der Waals magnet VI_(3) demonstrates intriguing magnetic properties that render it great for use in various applications.However,its microscopic magnetic structure has not been determined yet.Here,we report neutron diffraction and susceptibility measurements in VI_(3) that revealed a ferromagnetic order with the moment direction tilted from the c-axis by ~36° at 4 K.A spin reorientation accompanied by a structure distortion within the honeycomb plane is observed,before the magnetic order completely disappears at TC=50 K.The refined magnetic moment of ~1.3μB at 4 K is much lower than the fully ordered spin moment of 2μB/V^(3+),suggesting the presence of a considerable orbital moment antiparallel to the spin moment and strong spin-orbit coupling in VI_(3).This results in strong magnetoelastic interactions that make the magnetic properties of VI_(3) easily tunable via strain and pressure.
基金supported by the National Natural Science Foundation of China(Grant No.11874119)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)。
文摘The discovery of pressure-induced superconductivity in helimagnets(CrAs,MnP)has attracted considerable interest in understanding the relationship between complex magnetism and unconventional superconductivity.However,the nature of the magnetism and magnetic interactions that drive the unusual double-helical magnetic order in these materials remains unclear.Here,we report neutron scattering measurements of magnetic excitations in CrAs single crystals at ambient pressure.Our experiments reveal well defined spin wave excitations up to about 150 meV with a pseudogap below 7 meV,which can be effectively described by the Heisenberg model with nearest neighbor exchange interactions.Most surprisingly,the spin excitations are largely quenched above the Néel temperature,in contrast to cuprates and iron pnictides where the spectral weight is mostly preserved in the paramagnetic state.Our results suggest that the helimagnetic order is driven by strongly frustrated exchange interactions,and that CrAs is at the verge of itinerant and correlation-induced localized states,which is therefore highly pressure-tunable and favorable for superconductivity.
