Thermal annealing on the soft magnetism, microwave properties, and magnetostriction in Co-Fe-C alloy films

•The comprehensive magnetic properties of Co-Fe-C alloy films after thermal annealing was first systematically studied.•The direct evidence of high thermal stability in medium doping films is relative to stable structure and carbon distribution.•This manuscript will guide the annealing technical development on the fabrication and capsulation of magnetic devices.