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arXiv · 1007.2433

Pair density wave instability and Cooper pair insulators in gapped fermion systems

Predrag Nikolic·Anton A. Burkov·Arun Paramekanti
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Abstract

By analyzing simple models of fermions in lattice potentials we argue that the zero-temperature pairing instability of any ideal band-insulator occurs at a finite momentum. The resulting supersolid state is known as "pair density wave". The pairing momentum at the onset of instability is generally incommensurate as a result of phase-space restrictions and relative strengths of interband and intraband pairing. However, commensurate pairing occurs in the strong-coupling limit and becomes a Cooper-channel analogue of the Halperin-Rice exciton condensation instability in indirect bandgap semiconductors. The exceptional sensitivity of incommensurate pairing to quantum fluctuations can lead to a strongly-correlated insulating regime and a non-BCS transition, even in the case of weak coupling as shown by an exact renormalization group analysis.

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Predrag Nikolic, Anton A. Burkov, Arun Paramekanti. 2010-07-14. Pair density wave instability and Cooper pair insulators in gapped fermion systems. https://doi.org/10.1088/1742-6596/273/1/012012

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