Relation Between Microwave Complex Permeability and Ferromagnetic Fe-Si Layer Thickness in Mn-Ir/Fe-Si Exchange-Coupled Film

Mn-Ir/Fe-Si exchange-coupled films with an Ru underlayer for high frequency applications were fabricated, and their microwave permeability was evaluated. Both exchange bias field and ferromagnetic resonance frequency increased with decreasing Fe-Si thickness. For example, Mn-Ir (10 nm)/Fe-Si (10 nm)/Ru (1 nm) exchange-coupled film deposited on SiO
$_2$
had a static relative permeability of about 180 and a ferromagnetic resonance (FMR) frequency of about 4.3 GHz. The microwave properties such as permeability and FMR frequency can be controlled by changing Fe-Si thickness.