2009/01/31 by Predrag Nikolić, Predrag Nikolic
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Cooper pair #Fermion #Instability #Pairing #Phase (matter) #Phase diagram #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Quantum phase transition #Quantum, superfluid, helium dynamics #Superconductivity #Superfluidity #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.79.144507
published as Physical Review B 79, 144507 (2009) · 11 pages, 3 figures, published version
openalex publication_date 2009/04/07 · arxiv created 2012/06/08 · arxiv updated 2012/06/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We consider a generic two-dimensional system of fermionic particles with attractive interactions and no disorder. If time reversal symmetry is absent, it is possible to obtain incompressible insulating states in addition to the superfluid at zero temperature. The superfluid-insulator phase transition is found to be second order in type-II systems using a perturbative analysis of Cooper pairing instability in quantum Hall states of unpaired fermions. We obtain the pairing phase diagram as a function of chemical potential (density) and temperature. However, a more careful analysis presented here reveals that the pairing quantum phase transition is always preempted by another transition into a strongly correlated normal state which retains Cooper pairing and cannot be smoothly connected to the quantum Hall state of unpaired fermions. Such a normal phase can be qualitatively viewed as a liquid of vortices, although it may acquire conventional broken symmetries. Even if it did not survive at finite temperatures its influence would be felt through strong quantum fluctuations below a crossover temperature scale. These conclusions directly apply to fermionic ultracold-atom systems near unitarity, but are likely relevant for the properties of other strongly correlated superfluids as well, including high-temperature superconductors.