Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 3: Correlated Electrons: Heavy Fermions

TT 3.13: Vortrag

Montag, 26. März 2012, 12:45–13:00, H 3005

Metamagnetism and Lifshitz transitions in models for heavy fermions — •Martin Bercx and Fakher F. Assaad — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, 97074 Würzburg

We investigate metamagnetic transitions in models for heavy fermions by considering the metallic Kondo lattice model in two dimensions. Results are obtained within the framework of dynamical mean field and dynamical cluster approximation. Universal magnetization curves for different temperatures and Kondo couplings develop upon scaling with the lattice coherence temperature. Furthermore, the coupling of the local moments to the magnetic field is varied so as to take into account the different g-factors between localized and itinerant electrons. Competition between lattice coherence scale and Zeeman energy scale allow for two interpretations of the metamagnetism in heavy fermions: Kondo breakdown or Lifshitz transitions. By tracking the single particle residue through the transition and showing that it does not vanish at the transition, we can uniquely conclude in favour of the Lifshitz transition scenario.