Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Low-dimensional Systems: Models
TT 25.4: Vortrag
Dienstag, 8. März 2005, 10:45–11:00, TU H2053
Anomalous self-energy and Fermi surface quasi-splitting in the vicinity of a ferromagnetic instability — •Andrey Katanin1,2 and Arno Kampf3 — 1Max-Planck-Institut fuer Festkoerperforschung, 70569 Stuttgart, Germany — 2Institute of Metal Physics, 620219 Ekaterinburg, Russia — 3Institut fuer Physik, Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg, Germany
We discuss the low-temperature behavior of the electronic self-energy in the vicinity of a ferromagnetic instability in quasi-dimensional systems. We show, that in the paramagnetic phase, where the long-range magnetic order is absent, the self-energy has a non-Fermi liquid form at low energies |ω |< Δ 0 near the Fermi level, where Δ 0 is the ground-state spin splitting. The spectral function at temperatures T< Δ 0 has a two-peak structure with finite spectral weight at the Fermi level. The simultaneous inclusion of self-energy and vertex corrections shows that the above results remain qualitatively unchanged down to very low temperatures TC<T≪ Δ 0. It is argued, that this form of the spectral functions implies the quasi-splitting of the Fermi surface in the paramagnetic phase in the presence of strong ferromagnetic fluctuations.