Magneto-optical Kerr effect driven by spin accumulation on Cu, Au, and Pt

Abstract

The magneto-optical Kerr effect (MOKE) has recently been achieved on non-ferromagnetic metals by injecting spin currents. To use the magneto-optical Kerr effect as a quantitative tool, it is crucial to study the relationship between the Kerr rotation angle and the spin accumulation on non-ferromagnets. In this work, I measure a transient magneto-optical Kerr rotation on non-ferromagnetic metals of Cu, Au, and Pt driven by an ultrafast spin current from an adjacent ferromagnetic metal. Through comparing the measured Kerr rotation and the calculated spin accumulation, I determine the conversion ratio between the Kerr rotation and the spin accumulation to be: -4 × 10-9 (real part), -2.5 × 10-8 (real part), and -3 × 10-9 (imaginary part) rad m A-1 for Cu, Au, and Pt, respectively, at a wavelength of 784 nm.