Femtosecond Electron and Spin Dynamics in Gd(0001) Studied by Time-Resolved Photoemission and Magneto-optics

Abstract
Femtosecond electron and spin dynamics of the Gd(0001) surface are investigated by time-resolved photoemission and second harmonic generation. Upon optical excitation the spin polarization of the surface state is reduced by half while its exchange splitting remains nearly unchanged. Electron-magnon interaction is proposed to facilitate electron-spin-flip scattering among spin-mixed surface and bulk states, which provides a mechanism for ultrafast demagnetization.