Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: CE: Heavy Fermions
TT 26.15: Vortrag
Mittwoch, 24. März 2010, 18:00–18:15, H21
Phonons and the coherence scale of models of heavy fermions — •Marcin Raczkowski1, Peng Zhang1,2, Fakher F. Assaad1, Thomas Pruschke3, and Mark Jarrell2 — 1Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany — 2Department of Physics and Astronomy, Louisiana State University, Baton Rouge LA 70803, USA — 3Institute for Theoretical Physics, University of Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany
We consider models of heavy fermions in the strong coupling or local moment limit and include phonon degrees of freedom on the conduction electrons [1]. Due to the large mass or low coherence temperature of the heavy fermion state, it is shown that such a regime is dominated by vertex corrections which leads to the complete failure of the Migdal theorem. Even at weak electron-phonon couplings, binding of the conduction electrons competes with the Kondo effect and substantially reduces the coherence temperature, ultimately leading to the Kondo breakdown. Those results are obtained using a combination of the slave boson method and Migdal-Eliashberg approximation as well as the dynamical mean-field theory approximation. [1] arXiv:0910.2954v1