The influence of annealing temperature on structural, static, and dynamic magnetic properties of off-stoichiometric CoFeMnSi films

Abstract We reported the structural, static, and dynamic magnetic properties of off-stoichiometric CoFeMn0.8Si1.2 (CFMS) quaternary Heusler thin films deposited on MgO substrates with different annealing temperatures ranging from 500 to 750 °C. All films annealed above 500 °C achieve full B2 ordering, with XPS analysis confirming enhanced chemical ordering at 700 °C compared to 500 °C. These films display soft magnetic behavior, with a saturation magnetization of approximately 731.8 emu/cc for Ta =700 °C. Ferromagnetic resonance measurement results demonstrate that as the annealing temperature increases from 500 to 750 °C, the Gilbert damping factor initially decreases and then increases, reaching a minimum of 2.3×10-³ at 700 °C. First-principles calculations indicate that the off-stoichiometric B2 structure exhibits a considerably diminished density of states at the Fermi energy level. Therefore, the reduced Gilbert damping factor observed in the samples annealed at 700 °C is attributed to the interplay of the low density of states at the Fermi energy level and the high saturation magnetization strength.