Chiral magnetic excitations in FeGe films

Although chiral magnetic materials have emerged as a potential ingredient in future spintronic memory devices, there are few comprehensive studies of magnetic properties in scalably-grown thin films. We present growth, systematic physical and magnetic characterization, and microwave absorption spectroscopy of B20 FeGe thin films. We also perform micromagnetic simulations and analytical theory to understand the dynamical magnetic behavior of this material. We find magnetic resonance features in both the helical and field-polarized magnetic states that are well explained by micromagnetic simulations and analytical calculations. In particular, we show the resonant enhancement of spin waves along the FeGe film thickness that has a wave vector matching the helical vector. Using our analytic model, we also describe the resonance frequency of a helical magnetic state, which depends solely on its untwisting field. Our results pave the way for understanding and manipulating high frequency spin waves in thin-film chiral-magnet FeGe near room temperature.