Current-Induced Torques with Dresselhaus Symmetry Due to Resistance Anisotropy in 2D Materials.

Stiehl, Gregory M; MacNeill, David; Sivadas, Nikhil; El Baggari, Ismail; Guimarães, Marcos H D; Reynolds, Neal D; Kourkoutis, Lena F; Fennie, Craig J et al. · ACS Nano · 2019

basic_science · Level V

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Abstract

We report measurements of current-induced torques in heterostructures of Permalloy (Py) with TaTe<sub>2</sub>, 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 TaTe<sub>2</sub>. 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.