Magnetic properties and Mott transition in the Hubbard model on the anisotropic triangular lattice

作者：Yamada A^*

来源：Physical Review B, 2014, 89(19): 195108.

DOI：10.1103/PhysRevB.89.195108

Magnetic properties and the Mott transition are studied in the Hubbard model on the anisotropic triangular lattice described by two hopping parameters t and t %26apos; in different spatial directions using the variational cluster approximation. Taking into account Neel (AF), 120. Neel (spiral), and collinear (AFC) orderings, the magnetic phase diagram is analyzed at zero temperature and half-filling. We found six phases, AF metal, AF insulator, spiral, AFC, paramagnetic metal, and nonmagnetic insulator, which is a candidate for a spin liquid. Direct transitions from a paramagnetic metal to an AF insulator take place for 0.6 less than or similar to t%26apos; / t less than or similar to 0.8, and a nonmagnetic insulator is realized between the paramagnetic metal and magnetic states for 0.8 less than or similar to t%26apos; / t less than or similar to 1.2. Around t%26apos;/ t similar or equal to 1.2, the magnetic state (AFC or spiral) is realized above the paramagnetic metal, and as the on-site Coulomb repulsion U increases, it changes to a nonmagnetic insulator. Implications for the kappa-(BEDT-TTF)(2)Cu-2(CN)(3) are discussed. As for the Mott transition, the structure of the self-energy in the spectral representation is studied in detail. As U increases around the Mott transition point, a single dispersion evolves in the spectral weights of the self-energy, which yields the Mott gap.

• 出版日期2014-5-8