Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 47: Correlated Electrons: Spin Systems and Itinerant Magnets - Frustrated Magnets III
TT 47.8: Vortrag
Dienstag, 1. April 2014, 15:45–16:00, HSZ 03
Flat-band ferromagnetism and Pauli-correlated percolation — •Mykola Maksymenko1, Andreas Honecker2, Roderich Moessner1, Johannes Richter3, Oleg Derzhko4, and Kirill Shtengel5 — 1Max-Planck-Institut für Physik komplexer Systeme, Dresden — 2Institut für Theoretische Physik, Georg-August-Universität Göttingen — 3Institut für theoretische Physik, Universität Magdeburg — 4Institute for Condensed Matter Physics of NAS of Ukraine — 5University of California at Riverside
Flat-band ferromagnetism is a special case of magnetism due to correlated itinerant electrons in a number of geometrically frustrated lattices. We develop an exact mapping between ground states of this many-body problem and a novel site-percolation problem. This allows us to study the ferromagnetic transition using tools from equilibrium statistical physics. In the case of the Hubbard model on the Tasaki lattice, we provide a complete analytical treatment of the 1D case and show that for D > 1, the paramagnetic phase persists beyond the usual threshhold for uncorrelated percolation point. When the transition to an unsaturated ferromagnetic phase finally occurs, it is in the form of a first-order jump to an unsaturated ferromagnetic phase.