Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 12: Correlated Electrons: Spin Systems and Itinerant Magnets 2
TT 12.5: Vortrag
Montag, 23. März 2009, 15:15–15:30, HSZ 304
Quasiparticle Renormalization of Bulk Conduction Band States in a Ferromagnet at High Binding Energies — •A. Hofmann1, X. Y. Cui2, J. Schäfer1, S. Meyer1, P. Höpfner1, L. Patthey2, E. Rotenberg3, J. Bünemann4, F. Gebhard4, T. Ohm5, W. Weber5, and R. Claessen1 — 1Physikal. Institut, Universität Würzburg — 2Paul-Scherrer-Institut, Villigen — 3Lawrence Berkeley Nat. Laboratory — 4Universität Marburg — 5TU Dortmund
Many-body effects in metals can often be captured within the quasiparticle picture, where bare electrons become dressed with bosonic excitations. Angle-resolved photoemission (ARPES) is the probe of choice to detect such energy renormalization. Beyond electron-phonon coupling one expects interaction with spin excitations, which was identified in surface states of Fe(110) [1]. For bulk states, symmetry planes of k-space yield the desired hole spectral function.
By high-resolution ARPES we have studied the quasiparticle spectra of the ferromagnet Ni for binding energies up to 500 meV. Using a Gutzwiller calculation as reference, we find significant renormalization in the 250-300 meV range, as identified for magnetic bulk bands for the first time. The self-energy is well described within an electron-magnon coupling model, consistent with neutron scattering. The results also relate to a recent theoretical model [2], which describes kinks in correlated systems as transition between different renormalization regimes.
[1] J. Schäfer et al., Phys. Rev. Lett. 92, 097205 (2004).
[2] K. Byczuk et al., Nature Phys. 3, 168 (2007).