Phase diagram of half-filled square lattice for frustrated Hubbard model

✍ Scribed by Seiichiro Onari; Hisatoshi Yokoyama; Yukio Tanaka

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 142 KB
• Volume: 463-465
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2007.05.017

✦ Synopsis

Although the single-band Hubbard model for a half-filled square lattice is considered to be an antiferromagnetic (AF) insulator, it is a current vital question to ask what happens if the second nearest-neighbor hopping (t 0 ) is introduced to it. To study this problem, we use the fluctuation exchange (FLEX) approximation together with the variational Monte Carlo (VMC) method. We have obtained basically consistent results: A first-order Mott transition takes place at the Coulomb repulsion U = U c for a wide range of t 0 , and robust d-wave SC whose transition temperature is more than 0.01t (t is the nearest-neighbor hopping) appears near the AF and the Mott insulator region. We have also found that the superconductivity as well as an AF long-range order is suppressed as t 0 increases, because the AF spin fluctuation becomes weaker.