Combing the helical phase of chiral magnets with electric currents
Jan Masell, Xiuzhen Yu, Naoya Kanazawa, Yoshinori Tokura, Naoto Nagaosa
Abstract
The competition between the ferromagnetic exchange interaction and antisymmetric Dzyaloshinskii-Moriya interaction can stabilize a helical phase or support the formation of skyrmions. In thin films of chiral magnets, the current density can be large enough to unpin the helical phase and reveal its nontrivial dynamics. We theoretically study the dynamics of the helical phase under spin-transfer torques that reveal distinct orientation processes, driven by topological defects in the bulk or induced by edges, limited by instabilities at higher currents. Our experiments confirm the possibility of on-demand switching the helical orientation by current pulses. This helical orientation might serve as a novel order parameter in future spintronics applications.