期刊
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
卷 78, 期 12, 页码 -出版社
PHYSICAL SOC JAPAN
DOI: 10.1143/JPSJ.78.124706
关键词
iron oxypnictide superconductors; two-orbital Hubbard model; pairing symmetry; exact diagonalization
We investigate the electronic states of a one-dimensional two-orbital Hubbard model with band splitting by the exact diagonalization method. The Luttinger liquid parameter K-rho is calculated to obtain superconducting (SC) phase diagram as a function of on-site interactions: the intra- and inter-orbital Coulomb U and U', the Hund coupling J, and the pair transfer J'. In this model, electron and hole Fermi pockets are produced when the Fermi level crosses both the upper and lower orbital bands. We find that the system shows two types of SC phases, the SC I for U > U' and the SC II for U < U', in the wide parameter region including both weak and strong correlation regimes. Pairing correlation functions indicate that the most dominant pairing for the SC I (SC II) is the intersite (on-site) intraorbital spin-singlet with (without) sign reversal of the order parameters between two Fermi pockets. The result of the SC I is consistent with the sign-reversing s-wave pairing that has recently been proposed for iron oxypnictide superconductors.
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