Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 3: Correlated Electrons: Spin Systems and Itinerant Magnets 1
TT 3.4: Vortrag
Montag, 23. März 2009, 11:00–11:15, HSZ 304
Dynamical properties of kagome lattice models with charge degrees of freedom — •Aroon O’Brien1, Frank Pollmann2, and Peter Fulde1,3 — 1Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187 Dresden, Germany — 2University of California, Berkeley, CA94720, USA — 3Asia Pacific Center for Theoretical Physics, Pohang, Korea
Systems with frustrated interactions are typically characterized by a high density of low-lying excitations, leading to fascinating phenomena such as fractionalization. We study how charge degrees of freedom give rise to fractional charges in such systems.
For a spinless fermion model on a 2D checkerboard lattice, it is known that confined fractional charge excitations occur at certain filling factors. However, charge fractionalization, in the case of another 2D frustrated lattice, the kagome lattice, is not so thoroughly understood.
We investigate, through the calculation of spectral functions, models of spinless fermions and hardcore bosons respectively, at 1/3 filling on finite kagome lattices. Of particular interest is the strongly correlated limit, where excitations carrying fractional charges can occur. We derive an effective model pertaining to this regime and present our findings in relation to a quantum dimer model on the hexagonal lattice. We find that the effective Hamiltonian is bipartite, allowing us to determine a gauge transformation which cures the negative sign problem. We discuss further results through the comparison of the dynamical properties of the bosonic and fermionic models.