Superconductivity in a model of two Hubbard chains coupled with ferromagnetic exchange interaction

T. Shirakawa; S. Nishimoto; Y. Ohta

doi:10.1103/PhysRevB.77.224510

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Superconductivity in a model of two Hubbard chains coupled with ferromagnetic exchange interaction

T. Shirakawa, S. Nishimoto, Y. Ohta

DOI 10.1103/PhysRevB.77.224510 · Physical Review B

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Abstract

We study the ground-state properties of the double-chain Hubbard model coupled with ferromagnetic exchange interaction by using the weak-coupling theory, density-matrix renormalization-group technique, and Lanczos exact-diagonalization method. We determine the ground-state phase diagram in the parameter space of the ferromagnetic exchange interaction and band filling. We find that, in high electron-density regime, the spin gap opens and the spin-singlet dxy-wave-like pairing correlation is most dominant, whereas in low electron-density regime, the fully-polarized ferromagnetic state is stabilized where the spin-triplet py-wave-like pairing correlation is most dominant.