Critical field in a superconductivity model with local pairs

Marcin Mierzejewski; Maciej M. Maśka

doi:10.1103/PhysRevB.69.054502

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Critical field in a superconductivity model with local pairs

Marcin Mierzejewski, Maciej M. Maśka

DOI 10.1103/PhysRevB.69.054502 · Physical Review B

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Abstract

We analyze the role of Zeeman and orbital pair breaking mechanisms in models which are appropriate for short coherence length superconductors. In particular, we investigate attractive Hubbard and pair hopping models. The orbital pair breaking mechanism dominates in the majority of models with s-wave and d-wave superconducting order parameters. On the other hand, the repulsive pair hopping interaction leads to η type of pairing that is stable against the orbital pair breaking. External magnetic field reduces this type of pairing predominantly due to the Zeeman coupling. According to recent experiments this mechanism is responsible for closing of the pseudogap. Moreover, the temperature dependence of the gap closing field in η phase fits experimental data accurately. We discuss whether the preformed pairs in the η phase could be responsible for the pseudogap phenomenon.