Spin currents with unusual spin orientations in noncollinear Weyl antiferromagnetic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Mn</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mi>Sn</mml:mi></mml:mrow></mml:math>
Xinhao Wang, Mohammad Tomal Hossain, T. R. Thapaliya, Durga Khadka, Sergi Lendínez, Hang Chen, Matthew F. Doty, M. Benjamin Jungfleisch, Sunxiang Huang, Xin Fan, John Q. Xiao
Abstract
There are intensive efforts to search for mechanisms that lead to spin-orbit torque with unusual spin orientation, particularly out-of-plane spin orientation which can efficiently switch perpendicular magnetizations. Such a phenomenon has been observed in materials with low structural symmetry, ferromagnetic materials, and antiferromagnets with noncollinear spin structures. Here, we demonstrate the observation of, in addition to out-of-plane spin orientation, spin orientation along the charge current direction in ${\mathrm{Mn}}_{3}\mathrm{Sn}$, a noncollinear antiferromagnet and Weyl semimetal. The mechanism arises from noncollinear spin structure with spin-orbit coupling and it can be viewed as spin rotation around the octupole moment, the lowest order of cluster multipole moment pertaining to the ${\mathrm{Mn}}_{3}\mathrm{Sn}$ crystal group.