Estimation of Magnetic Gilbert Damping at High Temperature: An Approach of Ferromagnetic Resonance Study

High-temperature time-resolved magneto-optical Kerr effect microscopy, an updated version of the pump-probe laser technique, enables one to measure the magnetization dynamics at elevated temperatures and is established for the first time. An understanding of the damping mechanism with its dependence on temperature for highly anisotropic ferromagnetic materials is a crucial step toward the developmental approach for spintronic devices. So, in this work, we studied the magnetization dynamics of tetragonally distorted, highly anisotropic ultrathin Fe_0.5Co_0.5films at elevated temperatures. A clear dynamic response of magnetization was observed at elevated temperature and the damping decreased with increasing sample temperature. A monotonic decrease in resonance frequency and damping constant as a function of temperature can be ascribed due to the extrinsic contribution mechanism. The thermal dependence of the damping constant and effective anisotropic field measured from this ferromagnetic methodology is very important for such highly anisotropic materials for the development of memory devices. Based on the first-principle study and ferromagnetic resonance technology, we predict that the reduction of damping constant at elevated temperature might be influenced by two-magnon scattering instead of structural defects (tetragonal distortion), which can act as a potential origin.