Eur. Phys. J. B (2014) 87: 270
https://doi.org/10.1140/epjb/e2014-50585-2

Regular Article

Ground state pairing correlation competes in the doped triangular lattice Hubbard model

¹ Department of Physics, Beijing Normal University, Beijing 100875, P.R. China
² Beijing Computational Science Research Center, Beijing 100084, P.R. China

^a e-mail: txma@bnu.edu.cn

Received: 23 June 2014
Received in final form: 27 August 2014
Published online: 17 November 2014

Abstract

By using the constrained path quantum Monte carlo method, we study the ground state paring correlations in the t − U − V Hubbard model on the triangular lattice. It is shown that pairings with various symmetries dominate in different electron filling regions. The pairing correlation with fn-wave symmetry dominates over other pairings around half fillings, and as the electron filling decreases away from the half filling, the d + id-wave pairing correlation tends to dominate. As the electron filling is bellow the Van Hove singularity, the f-wave pairing dominates. These crossovers are due to the interplay of electronic correlation and geometric frustration, associating with the competition between the antiferromagnetic correlations and ferromagnetic fluctuations. Our findings reveal the possible magnetic origin of superconductivity, and also provide useful information for the understanding of superconductivity in Na_xCoO₂·H₂O and the organic compounds.