Zero temperature Phase Diagram of Two Dimensional Hubbard Model
Shared by: mainskweeze
Zero-temperature Phase Diagram of Two Dimensional Hubbard Model K. Inabaa , A. Kogab , S. Sugaa , and N. Kawakamib a Department of Applied Physics, Osaka University, Suita, Osaka 565-0871, Japan b Department of Physics, Kyoto University, Kyoto 606-8502, Japan Geometrical frustration has been one of the most active topics in the ﬁeld of strongly correlated elec- tron systems. In particular, recent experiments on the triangular lattice organic material κ-(BEDT- TTF)2 Cu2 (CN)3 have attracted much interest. According to an NMR experiment, the Mott insulating material κ-(ET)2 Cu2 (CN)3 does not exhibit any magnetic transition down to a quite low temperature T ∼32mK. It suggests that the geometrical frustration reveals a novel spin-liquid insulating state. Stimu- lated by the experimental ﬁnding, theoretical studies for the Hubbard model on an anisotropic triangular have been done by various methods1 . However, there is no consensus whether the non-magnetic insulating state is stable or not, and thus complemental discussions are desired. Motivated by this, we investigate the Hubbard model on the anisotropic triangular lattice, by the self-energy functional approach (SFA). The SFA provides us an eﬃcient and tractable way to deal with Mott transitions. In this study, we take into account two types of AF order, (i) (π, π)-AF order and (ii) 120◦ -AF order. We obtain the phase diagram of the model which is consistent with previous work. We ﬁnd that a 120◦ -AF order is dominant for t /t ≥ 0.8. In addition, we discuss whether the non-magnetic insulating phase is stable or not. 1 B.Kyung and A.S.Tremblay, Phys. Rev. Lett. 97, 046402 (2006); T. Mizusaki and M. Imada, Phys. Rev. B 74, 014421 (2006);T. Watanabe et. al., arXiv/0711.1702.