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 nonuniform 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.
Keywords: 2D materials; crystal symmetry; spin-torque; spin−orbit torque; transition metal dichalcogenides; van der Waals materials.