### Session B12: Organic Conductors and Strongly Correlated 2D Systems

11:15 AM–2:03 PM, Monday, March 10, 2008
Morial Convention Center Room: 203

Chair: Victor Yakovenko, University of Maryland

Abstract ID: BAPS.2008.MAR.B12.13

### Abstract: B12.00013 : Hall effect on the triangular lattice

1:39 PM–1:51 PM

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#### Authors:

(DPMC-MaNEP, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.)

Christophe Berthod
(DPMC-MaNEP, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.)

Thierry Giamarchi
(DPMC-MaNEP, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.)

Andrew Millis
(Department of Physics, Columbia University, 538 West, 120th Street, New York, NY 10027, USA)

We investigate the Hall effect on the two-dimensional triangular lattice. We calculate the high frequency Hall constant $R_H$ and its temperature dependence for three regimes of the Hubbard interaction $U$. In the non-interacting case $U=0$ we find that $R_H$ behaves at temperature $T=0$ like the classical dc Hall constant, $R_H\sim1/ne$. At high $T$ we find a positive $R_H$ increasing linearly with temperature, with a slope depending on the electron density. For small to moderate values of $U$, we study the effect of interactions on $R_H$ within second-order perturbation theory, and we find these effects to be small. The perturbation theory also shows that the electron self-energy is almost local ($k$-independent), suggesting the use of a local approximation as the Dynamical Mean Field Theory (DMFT) method to treat higher values of $U$. We therefore evaluate $R_H$ at large $U$ using both DMFT and the atomic limit of the self-energy, and we compare the results with those obtained at small $U$. Finally, we discuss the relevance of our calculations for the interpretation of recent Hall measurements in cobaltates.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.MAR.B12.13