1. Non-thermal electrons open the non-equilibrium pathway of the phase transition in FeRh
- Author
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Mattern, Maximilian, Rössle, Steffen Peer Zeuschner Matthias, Arregi, Jon Ander, Uhlíř, Vojtěch, and Bargheer, Matias
- Subjects
Condensed Matter - Materials Science - Abstract
We use ultrafast x-ray diffraction to study non-equilibrium pathways of the phase transition in FeRh parametrized by the structural response. By increasing the pump-pulse duration beyond the electron-phonon coupling time, we suppress the electron-phonon non-equilibrium present upon femtosecond laser excitation but still photoexcite electrons to non-thermal states. Irrespective of the pump pulse duration, we find an optically induced nucleation of ferromagnetic domains on an $8\,\text{ps}$ timescale that starts as soon as the successively deposited energy surpasses the site-specific threshold energy. If in contrast, FeRh is only indirectly excited by diffusion of thermalized electrons from an opaque Pt cap layer, the ferromagnetic phase rises on a $50\,\text{ps}$ timescale. These findings unambiguously identify the photo-excitation of non-thermal electrons and not electron-phonon non-equilibria to enable the non-equilibrium pathway of the phase transition in FeRh.
- Published
- 2023