Ultrafast hot-electron induced quenching of Tb4f magnetic order

TL;DR

This study demonstrates that femtosecond hot-electron pulses can rapidly quench Tb4f magnetic order in CoTb alloys, with demagnetization times depending on hot-electron thermalization, revealing insights into ultrafast magnetic dynamics.

Contribution

It provides the first comparison of non-thermal and thermal hot-electron effects on Tb4f magnetic quenching with detailed temporal analysis.

Findings

Non-thermal and thermal hot-electrons induce sub-picosecond demagnetization.

Demagnetization efficiencies are similar for both hot-electron types.

Thermal hot-electron demagnetization time is elongated due to propagation delay.

Abstract

We have investigated ultrafast quenching of the Tb4f magnetic order in Co74Tb26 alloys, induced by femtosecond hot-electrons pulses. The hot-electron pulses were produced in specific non-magnetic capping layers by infrared fs laser pulses. Our experimental results show that sub-picosecond dynamics of Tb4f magnetic moments can be induced by non-thermal and thermal hot-electrons. We further demonstrate that the demagnetization efficiencies of non-thermal and thermal hot electrons are similar. However, the characteristic demagnetization times show values of 0.35 ps for non-thermal hot-electrons excitations and 1.2 ps for thermal hot-electrons excitations. We explain this temporal elongation by the propagation time of thermal hot-electrons through the 15 nm thick CoTb film.