Theory of Condensed Matter: Hard Condensed Matter

March 6, 2018 at 2 p.m. in Galilei Raum, 01-128 (Staudinger Weg 9)

Prof. Dr. Jairo Sinova
Institut für Physik, SPICE

Chiral renormalization of magnetization dynamics through self-feedback
Kyoung-Whan Kim (JGU)

Chiral magnets are ferromagnetic systems that prefer a particular chirality due to the presence of spin-orbit coupling and broken inversion symmetry. They have received considerable attention due to their remarkable properties including spin-orbit torque, the Dzyaloshinskii-Moriya interaction, the existence of magnetic skyrmions, and anisotropic magnetoresistance. Analysis of chiral magnets mostly starts from the Landau- Lifshitz-Gilbert equation with additional terms corresponding to the Dzyaloshinskii-Moriya interaction and the spin-orbit torque. In this formalism, the chirality of equilibrium magnetic properties and that of non- equilibrium electron properties are only taken into account, while that of non-equilibrium magnetic properties are not taken into account.
In this talk, I would like to present the effects of chirality on the excitation and relaxation of magnetization. We examine self-feedback of chiral magnetization dynamics to demonstrate that the gyromagnetic ratio and the Gilbert damping effectively felt by the magnetic moments depend on the chirality of magnetic textures. We illustrate that the chiral renormalization of these parameters is non-negligible for systems with large spin-orbit torque. We also present how one can experimentally measure the chirality renormalized parameters by the domain wall motion in the flow and creep regimes. The qualitative changes from the chiral renormalization indicate that describing the dynamics of the magnetization in chiral magnets requires the chirality of these parameters to be taken into account.