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.
基金
supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0303100,2017YFA0302900,2016YFA0300500,2017YFA0206300,and 2019YFA0704900)
the National Natural Science Foundation of China(Grant Nos.11974392,11974394,11822411,51722106,11674372,11774399,11961160699,and 12061130200)
the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(CAS)(Grant Nos.XDB07020300,XDB25000000,and XDB33000000)
the Beijing Natural Science Foundation(Grant Nos.JQ19002,Z180008,and Z190009)
support from the Youth Innovation Promotion Association of CAS(Grant Nos.2013002,and 2016004)
support from the K.C.Wong Education Foundation(GJTD-2018-01)。
