Anomalous superconductivity and superfluidity in repulsive fermion systems
a Kapitza Institute of Physical Problems, Russian Academy of Sciences, ul. Kosygina 2, Moscow, 117334, Russian Federation
b National Research University Higher School of Economics, ul. Myasnitskaya 20, Moscow, 101000, Russian Federation
c L.V. Kirenskii Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Academgorodok 50, stroenie 38, Krasnoyarsk, 660036, Russian Federation
d Reshetnev Siberian State Aerospace University, prosp. Gazety Krasnoyarskii rabochii 31, Krasnoyarsk, 660014, Russian Federation
In review, we discuss the mechanisms of unconventional superconductivity and superfluidity in 3D and 2D fermionic systems with purely repulsive interaction at low density. We construct phase diagrams of these systems and find the areas of superconducting state in free space, as well as in the lattice in the framework of the Fermi-gas model with hard-core repulsion, Hubbard model, Shubin—Vonsovsky model, and t—J model. We demonstrate that the critical superconducting temperature can be strongly increased in a spin-polarized case or in a two-band situation already at low densities. The proposed theory is based on the Kohn—Luttinger mechanism or its generalizations and explains or predicts anomalous p-, d- and f-wave pairing in various materials, such as high-temperature superconductors, idealized monolayer and bilayer of doped graphene, heavy-fermion systems, layered organic superconductors, superfluid 3He, spin-polarized solutions 3He in 4He, ultracold quantum gases in magnetic traps and in the optical lattices.