Controlling spin current polarization through non-collinear antiferromagnetism

• Published in: Nature communications Vol. 11; no. 1; p. 4671
• Main Authors: Nan, T., Quintela, C. X., Irwin, J., Gurung, G., Shao, D. F., Gibbons, J., Campbell, N., Song, K., Choi, S. -Y., Guo, L., Johnson, R. D., Manuel, P., Chopdekar, R. V., Hallsteinsen, I., Tybell, T., Ryan, P. J., Kim, J. -W., Choi, Y., Radaelli, P. G., Ralph, D. C., Tsymbal, E. Y., Rzchowski, M. S., Eom, C. B.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16-09-2020; Nature Publishing Group; Nature Portfolio
• Subjects: 147/143; 639/301/119/1001; 639/766/119/1001; Antiferromagnetism; Crystal structure; Crystallinity; Electromagnetism; Energy efficiency; Ferromagnetism; Ferrous alloys; Hall effect; Heterostructures; Humanities and Social Sciences; Magnetic alloys; Magnetism; Magnetization; MATERIALS SCIENCE; multidisciplinary; Polarization; Polarization (spin alignment); Room temperature; Science; Science (multidisciplinary); Spin structure; Spintronics; Symmetry; Torque
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-17999-4

The interconversion of charge and spin currents via spin-Hall effect is essential for spintronics. Energy-efficient and deterministic switching of magnetization can be achieved when spin polarizations of these spin currents are collinear with the magnetization. However, symmetry conditions generally restrict spin polarizations to be orthogonal to both the charge and spin flows. Spin polarizations can deviate from such direction in nonmagnetic materials only when the crystalline symmetry is reduced. Here, we show control of the spin polarization direction by using a non-collinear antiferromagnet Mn
3
GaN, in which the triangular spin structure creates a low magnetic symmetry while maintaining a high crystalline symmetry. We demonstrate that epitaxial Mn
3
GaN/permalloy heterostructures can generate unconventional spin-orbit torques at room temperature corresponding to out-of-plane and Dresselhaus-like spin polarizations which are forbidden in any sample with two-fold rotational symmetry. Our results demonstrate an approach based on spin-structure design for controlling spin-orbit torque, enabling high-efficient antiferromagnetic spintronics.
In the typical spin-hall effect, spin-current, charge current, and spin polarisation are all mutually perpendicular, a feature enforced by symmetry. Here, using an anti-ferromagnet with a triangular spin structure, the authors demonstrate a spin-hall effect without a perpendicular spin alignment.