We report measurements of current-induced torques in heterostructures of Permalloy (Py) with TaTe2, a transition-metal dichalcogenide (TMD) material possessing low crystal symmetry, and observe a torque component with Dresselhaus symmetry. We suggest that the dominant mechanism for this Dresselhaus component is not a spin-orbit torque, but rather the Oersted field arising from a component of current that flows perpendicular to the applied voltage due to resistance anisotropy within the TaTe2. This type of transverse current is not present in wires made from a single uniform layer of a material with resistance anisotropy, but will result whenever a material with resistance anisotropy is integrated into a heterostructure with materials having different resistivities, thereby producing a spatially non-uniform pattern of current flow. This effect will therefore influence measurements in a wide variety of heterostructures incorporating 2D TMD materials and other materials with low crystal symmetries.
@article{arxiv.1901.08908,
title = {Current-Induced Torques with Dresselhaus Symmetry Due to Resistance Anisotropy in 2D Materials},
author = {Gregory M. Stiehl and David MacNeill and Nikhil Sivadas and Ismail El Baggari and Marcos H. D. Guimaraes and Neal D. Reynolds and Lena F. Kourkoutis and Craig J. Fennie and Robert A. Buhrman and Daniel C. Ralph},
journal= {arXiv preprint arXiv:1901.08908},
year = {2019}
}