Robust Magnetic Order Upon Ultrafast Excitation of an Antiferromagnet. Issue 36 (3rd November 2022)

• Record Type: Journal Article
• Authors: Lee, Sang‐Eun; Windsor, Yoav William; Fedorov, Alexander; Kliemt, Kristin; Krellner, Cornelius; Schüßler‐Langeheine, Christian; Pontius, Niko; Wolf, Martin; Atxitia, Unai; Vyalikh, Denis V.; Rettig, Laurenz
• Is Part Of: Advanced materials interfaces. Volume 9:Issue 36(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-03
• Subjects: antiferromagnet -- lanthanides -- microscopic three‐temperature model -- surface and bulk magnetism -- trARPES -- trRXD -- ultrafast spin dynamics; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.202201340
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: The ultrafast manipulation of magnetic order due to optical excitation is governed by the intricate flow of energy and momentum between the electron, lattice, and spin subsystems. While various models are commonly employed to describe these dynamics, a prominent example being the microscopic three temperature model (M3TM), systematic, quantitative comparisons to both the dynamics of energy flow and magnetic order are scarce. Here, an M3TM was applied to the ultrafast magnetic order dynamics of the layered antiferromagnet GdRh2 Si2 . The femtosecond dynamics of electronic temperature, surface ferromagnetic order, and bulk antiferromagnetic order were explored at various pump fluences employing time‐ and angle‐resolved photoemission spectroscopy and time‐resolved resonant magnetic soft X‐ray diffraction, respectively. After optical excitation, both the surface ferromagnetic order and the bulk antiferromagnetic order dynamics exhibit two‐step demagnetization behaviors with two similar timescales (<1 ps, ∼10 ps), indicating a strong exchange coupling between localized 4f and itinerant conduction electrons. Despite a good qualitative agreement, the M3TM predicts larger demagnetization than the experimental observation, which can be phenomenologically described by a transient, fluence‐dependent increased Néel temperature. The results indicate that effects beyond a mean‐field description have to be considered for a quantitative description of ultrafast magnetic order dynamics. Abstract : Femtosecond dynamics of electronic temperature, sub‐surface ferromagnetic ordering, and bulk 4f antiferromagnetic ordering of antiferromagnetic GdRh2 Si2 upon optical excitation are explored at various pump fluences. For consistent description of the demagnetization dynamics, the microscopic three temperature model is applied. While the model qualitatively describes the experimental results well, quantitatively, it suggests a systematic effective increase of the phase transition temperature.