Electric-field effect on the easy cone angle of the easy-cone state in CoFeB/MgO investigated by ferromagnetic resonance

摘要

We investigate the effect of an electric field on the cone angle of the easy-cone state in a CoFeB/MgO stack by ferromagnetic resonance as a function of temperature. We find that the easy cone state appears in the CoFeB/MgO system below 200 K. The application of electric field E modulates the effective first-order magnetic anisotropy energy constant, whereas the second-order magnetic anisotropy energy constant is almost independent of E, resulting in the variation of the cone angle by E. The present observation reveals the importance of the modulation of the magnetic anisotropy by E in magnetic tunnel junctions exhibiting an easy-cone state under spin-transfer-torque-induced switching. Published by AIP Publishing.