Spin Chirality: A Topological Variable of Magnetic Materials

Yuriy Mokrousov, Peter Grünberg Institut and University of Mainz

3pm (ET) Friday, September 10, 2021

Chiral magnetic materials steadily move to the center of attention owing to their unique properties which range from utter sensitivity to electrical currents, to a whole world of possible topological effects rooting in complex spin- and reciprocal-space behavior [1]. Here, I will show how the spin chirality, which is inherent to chiral magnets, emerges as a unique functional topological variable in magnetic materials. Conceptually, I will attempt to classify chirality-sensitive contributions to magneto-transport and magneto-optical properties of magnets based on the flavors of magnetic chirality, discussing possible applications of uncovered effects in the realm of spintronics which deals with creation, control and manipulation of the spin chirality as the key observable [1-3]. Further, I will show that chiral orbital transport effects may give rise to novel exchange interactions among spins which pave the way to the realization of novel topological three-dimensional spin textures such as hopfions [4]. Finally, I will also make it clear that discussed effects are not limited to systems which exhibit finite spin chirality in their ground state, but are inherent to wide classes of collinear ferromagnets and antiferromagnets subject to thermal fluctuations or excited by optical means [5]. The possibility of imprinting spin chirality by ultrafast laser pulses, combined with its topologically-robust behavior in magnets taken out of equilibrium makes spin chirality a very promising platform for novel paradigms in the realm of topological spintronics applications [6].

[1] Smejkal et al., Nat. Phys. 14, 242 (2018)
[2] Feng et al., Nat. Comm. 11, 118 (2020)
[3] Lux, Kipp et al., Comm. Phys. 4, 99 (2021); Phys. Rev. Lett. 124, 096602 (2020)
[4] Grytsiuk et al. Nat. Comm. 11, 511; Lux et al. Comm. Phys. 1, 60 (2018)
[5] Ghosh et al., arXiv:2011.01670; Zhang et al., Comm. Phys. 3, 227 (2020)
[6] Kerber et al., Nature Comm. 11, 6304 (2020)