SurfaceScience21 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 37: Poster Session III: Surface magnetism III

O 37.4: Poster

Dienstag, 2. März 2021, 10:30–12:30, P

The role of magnon-phonon hybridization in the lifetime broadening of surface states in rare-earth metals — •Bo Liu, Huijuan Xiao, and Martin Weinelt — Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany

Magnons and phonons are fundamental quasiparticle excitations in magnetic materials. Here we show that magnon-phonon hybridization plays an important role in the lifetime broadening of the surface state of ferromagnetic terbium due to large spin-lattice coupling in this material. This is evidenced by a comparison with Gd that has almost the same electronic structure as Tb but negligible 4f spin-orbit coupling. For the Gd surface state we show that magnon emission determines the photo-hole relaxation at low temperatures where the minority spin component exhibits clearly larger linewidth broadening than the majority component. With increasing temperature electron-phonon scattering becomes dominant evidenced by a larger coupling parameter λ in the majority spin channel. In contrast in Tb, majority and minority spin components of the surface state show very similar linewidths and the fitted electron-phonon coupling is twice as large as in Gd. The negligible spin dependence suggests the formation of magnon-polarons in line with our findings of ultrafast magnon emission in Tb [1].

[1] B. Frietsch et al., Science Advances 6, eabb1601 (2020).