Interplay between antiferromagnetism and superconductivity in the Hubbard model with frustration

✍ Scribed by Kenji Kobayashi; Hisatoshi Yokoyama

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 562 KB
• Volume: 469
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2009.02.017

✦ Synopsis

Coexistence of and competition between antiferromagnetism (AF) and d-wave superconductivity (SC) are studied for a Hubbard model on the square lattice with a diagonal transfer t 0 , using a variational Monte Carlo method. The following improvements are introduced into the trial function: (1) Coexistence of AF and d-wave singlet gaps that allows a continuous description of their interplay, (2) band renormalization effect, and (3) refined doublon-holon correlation factors. Optimizing this function for a strongly correlated value of U=t, we construct a phase diagram in the d (doping rate)-t 0 =t space, and find that for t 0 =t P À0:15 a coexisting state is realized, whose range of d extends as t 0 =t increases. In contrast, for t 0 =t ¼ À0:3, AF and SC states are mutually exclusive, and a coexisting state does not appear. In connection with the ''two-gap" problem, we confirm even for the present refined function that the gradient of momentum distribution function at the antinodal point mainly dominates the magnitude of the d-wave SC correlation function.