  Understanding the high-frequency transport characteristics of magnetic tunnel
junctions (MTJs) is crucial for the development of fast-operating spintronics
memories and radio frequency devices. Here, we present the study of
frequency-dependent capacitive current effect in CoFeB/MgO-based MTJs and its
influence on magnetization dynamics using time-resolved magneto-optical Kerr
effect technique. In our device operating at gigahertz frequencies, we find a
large displacement current of the order of mA's, which does not break the
tunnel barrier of the MTJ. Importantly, this current generates an Oersted field
and spin-orbit torque, inducing magnetization dynamics. Our discovery holds
promise for building robust MTJ devices operating under high current
conditions, also highlighting the significance of capacitive impedance in high
frequency magnetotransport techniques.
