Detection of Vortex Core Oscillation Using Second-Harmonic Voltage Detection Technique

A sensitive and reliable detection method for magnetic vortex core dynamics at the remanent state has been demonstrated. Perfectly symmetric potential created in a circular-shaped disk produces twofold symmetry in the position dependence of the resistance of the ferromagnetic disk. We find that the detectable second-harmonic voltage can be induced by flowing the dc current when the circular-shaped core oscillation is excited by the microwave magnetic field. The consistent features have been observed in the current dependence and field dependence of the signals, indicating that the present method is a powerful technique to characterize the core dynamics, even at the remanent state.