Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 1: Focussed Session: The Mott Transition in Model Systems

TT 1.4: Topical Talk

Montag, 23. März 2009, 12:00–12:30, HSZ 03

Mott Transition in Frustrated Lattice Systems — •Hirokazu Tsunetsugu — Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan

I will review in my talk our recent theoretical works on strongly correlated itinerant electrons on two typical frustrated lattices; Kagome and anisotropic triangular lattices. The main issues are how geometrical frustration modifies the Mott metal-insulator transition, one of the most interesting phenomena driven by strong correlation, and how magnetic correlations under frustration effects are related to coherence of electron dynamics, and also the possibility of new type of spin correlations near the transition point. To investigate these points, we have investigated a half-filled Hubbard model on these frustrated lattices by a cluster extension of dynamical mean field theory. In addition to the general trend of suppression of Mott transition, we found one-dimensional like spin correlations in the Kagome case and a reentrant insulator-metal-insulator crossover/transition in the anisotropic triangular lattice. The latter behavior is consistent with the phase diagram of κ-type ET salts experimentally determined by Kanoda group. Our results indicate that the interplay between large entropy inherent to spin frustration and short range antiferromagnetic correlation is responsible for this interesting reentrant behavior.

[1] T. Ohashi, N. Kawakami, and H. Tsunetsugu, Phys. Rev. Lett. 97, 066401 (2006).

[2] T. Ohashi, T. Momoi, H. Tsunetsugu, and N. Kawakami, Phys. Rev. Lett. 100, 076402 (2008).