Direct transition between a singlet Mott insulator and a superconductor.
We argue that a normal Fermi liquid and a singlet, spin-gapped Mott insulator cannot be continuously connected, and that some intermediate phase must intrude between them. By explicitly working out a case study where the singlet insulator is stabilized by orbital degeneracy and an inverted Hund's rule coupling, mimicking a Jahn-Teller effect, we find that the intermediate phase is a superconductor.
Capone
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International School for Advanced Studies (SISSA), and Istituto Nazionale per la Fisica della Materia (INFM) Unità Trieste-SISSA, Via Beirut 2-4, I-34014 Trieste, Italy.
Fabrizio
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Tosatti
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