FMR studies of CrO₂ epitaxial thin films

Abstract

Epitaxial (100) thin films of CrO2 of various thickness were fabricated by chemical vapor deposition (CVD) at atmospheric oxygen pressure onto (100) TiO2 single-crystal substrates. Ferromagnetic resonance (FMR) measurements were performed at the X-band (9.5 GHz) at room temperature. The angular dependencies of the FMR spectra in both "in-plane" and "out-of-plane" geometries were measured. The directions of easy and hard axes of magnetization were determined from the in-plane measurements, when the DC magnetic field was rotated in the film plane. It was established that, at room temperature, the easy axis of magnetization is parallel to the c-axis of the CrO2 rutile structure. Splitting of the FMR signal into surface and bulk modes was observed due to surface pinning of magnetization at interfaces of the CrO2 films. The magnetoelastic anisotropy was observed to be enhanced with decreasing film thickness. The values of the room temperature effective magnetization and parameters of the anisotropy field were obtained from analysis of the FMR data. © 2003 Elsevier B.V. All rights reserved.