Anomalous Magnetization Dynamics After Dual Optical Excitation

Abstract

ABSTRACT Ultrafast optical excitation is widely used to manipulate electronic and magnetic properties of materials on femtosecond timescales. In this study, we investigate the response of copper to circularly polarized femtosecond pulses using time‐resolved magneto‐optical Kerr effect measurements. We compare the dynamics induced by single‐pulse excitation with those resulting from a dual‐pump configuration, in which two pulses arrive simultaneously from different directions. Although the individual contributions of the two pumps are similar when applied separately, their combined effect leads to a marked change in the spin/orbital dynamics. Specifically, we observe an approximately 2.5‐fold increase in the decay time of the spin/orbital imbalance signal under dual‐pump excitation. This result indicates that the joint action of two optical pulses can qualitatively alter the relaxation pathways in the system, beyond a simple additive response. The observed behavior highlights a previously unexplored regime of light‐induced dynamics and suggests new strategies for controlling ultrafast processes in solids.

Affiliated Institutions

• Uppsala University SE
• European X-Ray Free-Electron Laser DE

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