Spin excitations and spin wave gap in the ferromagnetic Weyl semimetal Co3Sn2S2

作者：Chang Liu,JianLei Shen,JiaCheng Gao,ChangJiang Yi,Di Liu,Tao Xie,Lin Yang,Sergey Danilkin,GuoChu Deng,WenHong Wang,ShiLiang Li,YouGuo Shi,HongMing Weng,EnKe Liu,HuiQian Luo

摘要：We report a comprehensive neutron scattering study on the spin excitations in the magnetic Weyl semimetal Co3Sn2S2 with a quasi-two-dimensional structure.Both in-plane and out-of-plane dispersions of the spin waves were revealed in the ferromagnetic state.Similarly,dispersive but damped spin excitations were found in the paramagnetic state.The effective exchange interactions were estimated using a semi-classical Heisenberg model to consistently reproduce the experimental TCand spin stiffness.However,a full spin wave gap below Eg=2.3 meV was observed at T=4 K.This value was considerably larger than the estimated magnetic anisotropy energy(~0.6 meV),and its temperature dependence indicated a significant contribution from the Weyl fermions.These results suggest that Co3Sn2S2 is a three-dimensional correlated system with a large spin stiffness,and the low-energy spin dynamics can interplay with the topological electron states.

发文机构：Beijing National Laboratory for Condensed Matter Physics School of Physical Sciences Australian Centre for Neutron Scattering Songshan Lake Materials Laboratory Physical Science Laboratory

关键词：magneticWeylsemimetaltopologicalmaterialsspinexcitationsneutronscattering

分类号： O57[理学—粒子物理与原子核物理]