Ultrafast demagnetization at high temperatures

TL;DR

This study investigates how ultrafast demagnetization in Co/Pd superlattices varies with temperature, showing that higher heat accumulation enhances initial demagnetization but diminishes it near the Curie point, aligning with a spin-flip scattering model.

Contribution

It provides experimental insights into the temperature dependence of ultrafast demagnetization and validates the spin-flip scattering model at high temperatures.

Findings

Demagnetization increases with heat accumulation at lower temperatures.

Near the Curie temperature, ultrafast demagnetization diminishes.

Spin-flip scattering model accurately describes the transient magnetization dynamics.

Abstract

Time-resolved pump-probe measurements were made at variable heat accumulation in Co/Pd superlattices. Heat accumulation increases the baseline temperature and decreases the equilibrium magnetization. Transient ultrafast demagnetization first develops with higher fluence in parallel with strong equilibrium thermal spin fluctuations. The ultrafast demagnetization is then gradually removed as the equilibrium temperature approaches the Curie temperature. The transient magnetization time-dependence is fit well with the spin-flip scattering model.