Non-thermal electrons open the non-equilibrium pathway of the phase transition in FeRh

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.

References in corpus (10)

• Phononic Switching of Magnetization by the Ultrafast Barnett Effect
• Tunneling anisotropic magnetoresistance driven by magnetic phase transition
• Driving ferromagnets into a critical region of a magnetic phase diagram
• Concepts and use cases for picosecond ultrasonics with x-rays
• All-optical seeding of a light-induced phase transition with correlated disorder
• Strain and voltage control of magnetic and electric properties of FeRh films
• Ultrafast Demagnetization through Femtosecond Generation of Non-thermal Magnons
• Speed limits of the laser-induced phase transition in FeRh
• Controlling effective field contributions to laser-induced magnetization precession by heterostructure design
• Accelerating the laser-induced phase transition in nanostructured FeRh via plasmonic absorption

Cited by in corpus (1)

• Dislocation-Driven Nucleation Type Switching Across Repeated Ultrafast Magnetostructural Phase Transition