Oscillatory Paramagnetic Magneto-Optical Kerr Effect in Ru Wedges on Co

Abstract

Sharp, quantum-well-like resonances in the field dependent polar magneto-optical Kerr effect of evaporated Ru wedges on perpendicularly magnetized Co as a function of the Ru thickness are reported. This effect selectively measures free electronic excitations in Ru and is, via the Pauli paramagnetic susceptibility, proportional to the free electron density of states at the Fermi level. A peak separation of 1.2 nm agrees with long period indirect magnetic exchange coupling oscillations in perpendicular Co/Ru-wedge/Co sandwiches.