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

• Published in: ACS nano Vol. 13
• Main Authors: Stiehl, Gregory M., MacNeill, David, Sivadas, Nikhil, El Baggari, Ismail, Guimarães, Marcos H. D., Reynolds, Neal D., Kourkoutis, Lena F., Fennie, Craig J., Buhrman, Robert A., Ralph, Daniel C.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society (ACS) 07-01-2019
• Subjects: 2D materials; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; crystal symmetry; group theory; heterostructures; layers; magnetic properties; quantum mechanics; spin-torque; spin−orbit torque; transition metal dichalcogenides; van der Waals materials
• ISSN: 1936-0851; 1936-086X

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. Furthermore, this effect will therefore influence measurements in a wide variety of heterostructures incorporating 2D TMD materials and other materials with low crystal symmetries.