Superconductivity in a Correlated E⊗e Jahn–Teller System
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By numerically solving the Eliashberg equation in the RPA as well as employing the Landau’s theory for phase transitions, we have investigated superconductivity, especially its pairing character, in a two-orbital Hubbard model coupled with E⊗e Jahn–Teller phonons on a two-dimensional square lattice at half filling. If the electron hopping between neighboring sites keeps the orbital character invariant in this E⊗e Jahn–Teller crystal, we find that a new superconducting phase characterized by the pairing of spin singlet, orbital singlet, and odd in momentum space, named a chiral p-wave pairing, is brought about by the collaboration of orbital fluctuations enhanced mainly by the electron–phonon interaction with spin fluctuations induced by the electron–electron one.
KeywordsSuperconductivity Jahn–Teller interaction Orbital fluctuation Two-orbital Hubbard model
This work is partially supported by Global COE Program “the Physical Sciences Frontier,” a Grant-in-Aid for Scientific Research (C) (No. 21540353), and Innovative Area “Materials Design through Computics: Complex Correlation and Non-Equillibrium Dynamics” (No. 22104011) from MEXT, Japan.