Metal-Insulator-Superconductor Transition in Two-Channel Interacting Many-Body Systems

Parhat Niyaz

Alexandre M. Zagoskin

Y. M. Malozovsky, J. D. Fan

Using the Fermi-liquid approach with vertex corrections, the effects of exchange and correlation are considered in a layered two-dimensional electron gas. It is shown that the interaction in the particle–hole channel can induce the metal–insulator phase transition when the Fermi momentum is comparable with the inverse interlayer spacing, pF ≈︂ /1c. The possibility of superconductivity in the region between the insulator and normal metal phases, taking into account the particle–hole excitations, is discussed. A smooth crossover from weak to strong coupling superconductivity with the decrease of the 2D carrier density is obtained. The results suggest a new way in the explanation of the phase diagram of layered high-Tc superconductors.

N. Bergeal, Johan Biscaras, Simon Hurand +6 more

Alexander L. Chudnovskiy, Alex Kamenev

We present a model of a strongly correlated system with a non-Fermi liquid high temperature phase. Its ground state undergoes an insulator to superconductor quantum phase transition (QPT) as a function of a pairing interaction strength. Both the insulator and the superconductor are originating from the same interaction mechanism. The resistivity in the insulating phase exhibits the activation behavior with the activation energy, which goes to zero at the QPT. This leads to a wide quantum critical regime with an algebraic temperature dependence of the resistivity. Upon raising the temperature in the superconducting phase, the model exhibits a finite temperature phase transition to a Bose metal phase, which separates the superconductor from the non-Fermi liquid metal.

Theja N. De Silva

We use a slave-rotor approach within a mean-field theory to study the competition of metallic, Mott-insulating, and superconducting phases of spin-3/2 fermions subjected to a periodic optical lattice potential. In addition to the metallic, the Mott-insulating, and the superconducting phases that are associated with the gauge symmetry breaking of the spinon field, we identify an emerging superconducting phase that breaks both roton and spinon field gauge symmetries. This superconducting phase emerges as a result of the competition between spin-0 singlet and spin-2 quintet interaction channels naturally available for spin-3/2 systems. The two superconducting phases can be distinguished from each other by quasiparticle weight. We further discuss the properties of these phases for both two-dimensional square and three-dimensional cubic lattices at zero and finite temperatures.