Thin highly textured Fe1+xCo2−xSi (0≤ x ≤1) films were prepared on MgO (001) substrates by magnetron co-sputtering. The magneto-optic Kerr effect (MOKE) and ferromagnetic resonance (FMR) measurements were used to investigate the composition dependence of the magnetization, the magnetic anisotropy, the gyromagnetic ratio and the relaxation of the films. The effective magnetization for the thin Fe1+xCo2−xSi films, determined by FMR measurements, are consistent with the Slater Pauling prediction. Both MOKE and FMR measurements reveal a pronounced fourfold anisotropy distribution for all films. In addition we found a strong influence of the stoichiometry on the anisotropy as the cubic anisotropy strongly increases with increasing Fe concentration. The gyromagnetic ratio is only weakly dependent on the composition. We find low Gilbert damping parameters for all films with values down to 0.0012±0.00012 for Fe1.75Co1.25Si. The effective damping parameter for Co2FeSi is found to be 0.0018±0.0004. We also find a pronounced anisotropic relaxation, which indicates significant contributions of two-magnon scattering processes that is strongest along the easy axes of the films. This makes thin Fe1+xCo2−xSi films ideal materials for the application in STT-MRAM devices.
@article{arxiv.1605.06797,
title = {Low Gilbert damping in Co2FeSi and Fe2CoSi films},
author = {Christian Sterwerf and Soumalya Paul and Behrouz Khodadadi and Markus Meinert and Jan-Michael Schmalhorst and Mathias Buchmeier and Claudia K. A. Mewes and Tim Mewes and Günter Reiss},
journal= {arXiv preprint arXiv:1605.06797},
year = {2016}
}