Chirality control of the spin structure in monoaxial helimagnets by charge current

Abstract

Chirality control of the spin structure in monoaxial helimagnets by using charge current is theoretically investigated. The classical J1−J2 Heisenberg model has two degenerate helical states that are characterized by the chirality. In a recent experiment, it has been shown that the chirality of the spin structure can be controlled by applying a charge current during the field-decreasing process [Jiang et al., Nat. Commun. 11, 1601 (2020)]. We reproduced this experiment by numerical calculations based on the Landau–Lifshitz–Gilbert equation with the spin-transfer torque. We show that the damping torque and spin-transfer torque are responsible for the controllability. In addition, we theoretically propose more convenient forms of chirality control: instantaneous switching of chirality and zero-field control by using a ferromagnet junction. Such improved controllability may pave the way to spintronics based on the chirality degree of freedom.