Regensburg 2004 – scientific programme
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TT: Tiefe Temperaturen
TT 15: Korrelierte Elektronen: Theorie I
TT 15.5: Talk
Tuesday, March 9, 2004, 15:30–15:45, H19
Low-energy charge excitations on frustrated lattices — •Erich Runge — Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
We study strongly interacting electrons on frustrated lattices of complex topology. Often, these systems have a huge phase space for low-lying excitations. In the case of LiV2O4, this leads to heavy-fermion behavior. However, the nature of the low-energy excitations is generally not well understood. It has even been predicted that fractionally charged quasi-particles exist in two and three dimensions [1].
We discuss in detail the interplay of the frustrated kinetic energy and the Coulomb repulsion between nearest-neighbor sites. An effective Hamiltonian for the low-energy excitations is derived, which involves ring exchanges and shows a huge density of states of non-magnetic excitations. It can serve as a prototype for a new class of effective interactions and quasi-particles.
Large-scale numerical results for the spectral function and related quantities are presented as well.
[1] Peter Fulde, Karlo Penc, and Nic Shannon, Fractional charges in pyrochlore lattices, Annalen der Physik 11, 892 (2002)