Element-resolved ultrafast demagnetization rates in ferrimagnetic CoDy

Abstract

Femtosecond laser induced ultrafast magnetization dynamics have been studied in multisublattice CoxDy1-x alloys. By performing element and time-resolved X-ray spectroscopy, we distinguish the ultrafast quenching of Co3d and Dy4f magnetic order when the initial temperatures are below (T=150K) or above (T=270K) the temperature of magnetic compensation (Tcomp). In accordance with former element-resolved investigations and theoretical calculations, we observe different dynamics for Co3d and Dy4f spins. In addition we observe that, for a given laser fluence, the demagnetization amplitudes and demagnetization times are not affected by the existence of a temperature of magnetic compensation. However, our experiment reveals a twofold increase of the ultrafast demagnetization rates for the Dy sublattice at low temperature. In parallel, we measure a constant demagnetization rate of the Co3d sublattice above and below Tcomp. This intriguing difference between the Dy4f and Co3d sublattices calls for further theoretical and experimental investigations.

arXiv comment6 Figure, 2 Tables

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Cited by in corpus (5)

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• Single shot time-resolved magnetic x-ray absorption at a Free Electron Laser
• Ultrafast hot-electron induced quenching of Tb4f magnetic order
• Time-Resolved XUV absorption spectroscopy and magnetic circular dichroism at the Ni $M_{2,3}$-edges