Magnetization reversal and Gilbert damping in Co2FeAl0.5Si0.5 (CFAS) quaternary Heusler alloy

In this work, study of M
r
/M
s
, H
c
, resonance field (H
r
) and linewidth (ΔH) as functions of the magnetic field angle for the CFAS films of varying thickness (t) by longitutional magneto-optical Kerr rotation (L-MOKE) and ferromagnetic resonance (FMR) techniques establishes the presence of in-plane uniaxial anisotropy. The observed variation of H
c
with the azimuthal field angle is well described by the two-phase model. In the CFAS films with t = 12 nm, 25 nm and 75 nm, magnetization reversal occurs through the formation of ripple domains, while for t = 50 nm CFAS films, the reverse 180° domain nucleates and grows by domain wall movement with increasing external magnetic field. The contributions to the FMR linewidth from the inhomogeneity, two-magnon scattering and Landau-Lifshitz-Gilbert (LLG) damping are estimated. The lowest (intrinsic) LLG parameter (α) of 0.002 is deduced for the film with t = 50 nm. Our results provide crucial information about the magnetization dynamics and damping in CFAS thin films which will be usefull for applications in spintronics devices.