Photovoltage Spectroscopy of Dipolar Spin Waves in Dy Micromagnets

We report on a sensitive spectroscopic technique for probing the spin excitations of individual submicron magnets. This technique uses a high mobility two dimensional electron gas (2DEG) confined in a GaAs/AlGaAs heterojunction to pick up the oscillating dipolar magnetic field emanating from the individual spin wave modes of micromagnets fabricated at its surface. We review a range of dynamic phenomena that demonstrate the formation of magnetostatic waves in finger gate arrays, dipolar edge spin waves in bar magnets, vortex hysteresis in magnetic dots and the photovoltage dependence on microwave polarization.