CoFeB Thickness Dependence of Damping Constants for Single and Double CoFeB-MgO Interface Structures

We investigate the CoFeB thickness dependence of the damping constant α of single and double CoFeB-MgO interface structures by vector-network-analyzer ferromagnetic resonance (VNA-FMR). The damping constant increases with decreasing the CoFeB thickness for the single interface structure, and the damping constant for the double-interface structure takes a similar value to that for the single-interface structures with the same CoFeB thickness.