Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 28: Correlated Electrons: General Theory
TT 28.11: Vortrag
Donnerstag, 30. März 2006, 12:45–13:00, HSZ 301
Exotic excitations with fractional charges on frustrated lattices — •Frank Pollmann1, Peter Fulde1, and Erich Runge2 — 1Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany — 2Technische Universität Ilmenau, Weimarer Str. 25, 98693 Ilmenau, Germany
Geometrical frustration of lattices can lead to a macroscopic degeneracy
in the classical limit and thus to many interesting physical effects.
In spin systems these are e.g. translational invariant spin liquid
ground states and deconfined spinons. In contrast to magnetic properties,
one began only recently to explore the charge degrees of freedom on
frustrated lattices.
For the systematic study of charge degrees of freedom, we consider
a model of spinless fermions with nearest-neighbor hopping t and
Coulomb repulsion V. Quantum fluctuations reduce the classical
(t=0) macroscopic degeneracy. For the strongly correlated limit
V≫|t|, it has been predicted that an added electron can decay
into two mobile quasi-particles, leading to fractional charges of
e/2 in 2D and 3D systems.
For a deeper understanding of these charge degrees of freedom we calculated
numerically the properties of static and dynamic charges on the 2D
checkerboard lattice. Evidence for a weak mutual confinement of two
fractional charges is found, leading to excitations with very large
spatial extend. We argue that the fractional charges should be deconfined
on the 3D pyrochlore lattice.