Ferromagnetic resonance, transverse bias initial inverse susceptibility and torque studies of magnetic properties of Co₂MnSi thin films

¹ LSPM (CNRS-UPR 3407) Université Paris 13, 99 avenue Jean-Baptiste Clément, 93430 Villetaneuse, France
² IS2M (CNRS-LRC 7228) Université de Haute-Alsace, 15 Rue Jean Starcky BP2488, 68093 Mulhouse, France
³ IEF (CNRS UMR8622), Université Paris-Sud, 91405 Orsay, France
⁴ Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

Abstract

Magnetic properties of Co2MnSi thin films of 20 nm and 50 nm in thickness grown by radio frequency sputtering on a-plane sapphire substrates have been studied. X-ray diffraction (XRD) revealed that the cubic <110> Co₂MnSi axis is normal to the substrate and that well defined preferential in-plane orientations are present. The static magnetic properties were studied at room temperature by conventional magneto-optical Kerr effect (MOKE), transverse bias initial inverse susceptibility and torque (TBIIST) MOKE. The dynamic magnetic properties were investigated by micro-strip ferromagnetic resonance (MS-FMR) at room temperature. The resonance and TBIIST measurements versus the direction of the in-plane applied magnetic field reveal that the in-plane anisotropy results from the superposition of a two-fold and a four-fold symmetry. The directions of the principal axes of the twofold anisotropy are sample dependent. The angular dependence of remanent normalized magnetizations and coercive fields, studied by MOKE are analyzed within the frame of a coherent rotation model. A good agreement is observed between the field anisotropy values obtained from MSFMR and from TBIIST data. Frequency and angular dependence of FMR linewidth has been studied. Apparent damping coefficient of 0.0112 has been measured for 50 nm thick sample.