Heisenberg vs. Stoner: Ultrafast magnon generation and exchange renormalization in the course of laser-induced demagnetization
ORAL
Abstract
In this work, we access the microscopic mechanisms responsible for the ultrafast magnetization dynamics of ferromagnets following a femtosecond laser excitation. Using a tabletop high-harmonic source of extreme ultraviolet light, we perform magneto-optical pump-probe spectroscopic studies across the M$_{\mathrm{2,3}}$ absorption edge of Cobalt with time, energy and angle resolution. This novel approach allows us to extract the time-dependent resonant magneto-optical properties of the Cobalt sample. In combination with ab-initio calculations of the density of states and the magneto-optical response, this gives us indirect access to ultrafast dynamics of the band structure. A comparison of our theoretical simulations with the experimental measurements suggests a variety of demagnetization mechanisms, which include ultrafast magnon excitations, enhanced electron temperature and transient renormalization of exchange splitting.
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