Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 14: Spin Systems and Itinerant Magnets

TT 14.8: Vortrag

Dienstag, 27. März 2007, 16:15–16:30, H19

Correlated spinless fermions on a checkerboard lattice — •Olga Sikora, Frank Pollmann, and Peter Fulde — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany

Possible fractionalization of quantum numbers on frustrated lattices has recently attracted a lot of interest. In particular, it has been suggested that charge fractionalization might occur in a model of strongly correlated spinless fermions on a planar pyrochlore (checkerboard) lattice.

We consider a quarter– and half–filled checkerboard lattice in the limit of strong nearest–neighbor interactions V (V≫|t|, where t is a hopping integral). The low–energy excitations are described by an effective Hamiltonian which is given to the lowest non-vanishing order by ring exchange around hexagons. A gauge transformation allows to remove the fermionic sign problem and the system can be described by an effective bosonic model. We use the Green’s function Monte Carlo method to study the quantum mechanical ground state of the effective Hamiltonian. The method is verified by a comparison with the results for small clusters obtained by exact diagonalization method.