Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Correlated Electrons: Poster Session
TT 32.78: Poster
Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B
Electronic Quasiparticles on the Spin-Wave Energy Scale in Ferromagnets — •Andreas Hofmann1, Xiaoyu Cui1, Jörg Schäfer1, Eli Rotenberg2, Luc Patthey3, and Ralph Claessen1 — 1Universität Würzburg, D-97074 Würzburg — 2Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA — 3Paul-Scherrer-Institut, CH-5232 Villigen
Angle-resolved photoemission (ARPES) is excellently suited to resolve energy renormalization of electronic quasiparticles dressed with an excitation. Beyond electron-phonon coupling, one must expect the fingerprint of magnetic excitations. Significant mass enhancement due to spin excitations has been identified for the first time in metallic surface states of Fe(110) [1]. The energy window exceeds that of phonons by far and is in striking coincidence with the spin wave spectrum.
Bulk bands of magnetic materials are also subject to strong mass enhancement, as reflected e.g. in the Fermi velocity. In most recent experiments on Ni(110) using ARPES, the question has been addressed whether such electronic self-energy effects can be resolved in the spectral function. In taking ARPES data at symmetry planes of the Ni Fermi surface, structure is indeed observed in the real and imaginary parts of the self-energy. The energy scale of 200-300 meV coincides with characteristic spin wave energies. Moreover, the bulk bands show indication of two simultaneous kinks, on both the phonon and spin wave energy scale. The consequences of such experiments will be analyzed.
J. Schäfer et al., Phys. Rev. Lett. 92, 097205 (2004).