Variational Monte Carlo study of pairing symmetry in Sr2RuO4

• Published in: Physica. C, Superconductivity Vol. 463-465; pp. 134 - 137
• Main Authors: Fujita, Shogo, Watanabe, Tsutomu, Onari, Seiichiro, Yokoyama, Hisatoshi, Tanaka, Yukio, Inoue, Jun-ichiro
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2007; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Hubbard model; Pairing symmetries; Physics; Superconductivity; Theory and models of superconducting state; Unconventional superconductor; Variational Monte Carlo; 74.70.−b; Unconventional superconductor; 74.20.−z; Hubbard model; Variational Monte Carlo; Variational methods; 74.70.-b; 74.20.-z; Superconductivity; Singlet state; Coulomb interaction; Holon; Optimization; Triplet state; Monte Carlo methods; Superconductors; Ruthenates; Binding energy; Strontium compounds; Wave functions; Pairing symmetry; Square lattices; Unconventional superconductor; Hubbard model; Variational Monte Carlo; Trial function
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2006.12.026

With a mind to superconductivity (SC) arising in Sr2RuO4, we study a Hubbard model on square lattice including second-neighbor hopping t′, using an optimization variational Monte Carlo method. As a pairing state, we have chosen dx2-y2(d) wave for singlet and px (p)-wave for triplet pairing state. In the trial wave functions, a doublon–holon binding effect is introduced in addition to the onsite Gutzwiller projection. By calculating condensation energies of the SC states, we found that when t′=−0.4t, the d-wave state is stabilized against the normal state for 0.6<n<1. On the other hand, p-wave state is never stabilized in this regime. Based on this result, it is difficult to understand a spin-triplet state simply from the single-band Hubbard model with onsite Coulomb interaction.