Superconducting states with a mixed symmetry of order parameters in the model of a two-dimensional Fermi liquid

Abstract

The possibility has been investigated of the appearance of superconducting states with a mixed symmetry of order parameters in the model of two-dimensional Fermi liquid with a cylindrical Fermi surface. It has been shown that the superconducting states to be mixed, if having different symmetry corresponding to any two different harmonics of the gap function, should be shifted in phase with respect to one another by an angle of ±π/2. It has been established that at the zero temperature the region of the existence of the phase with a mixed symmetry of the superconducting order parameters is restricted to a narrow window of the ratios of the amplitudes of interaction from different pairing channels that are concentrated near the critical value of the ratio of these amplitudes corresponding to the point of intersection of the lines of the temperatures of superconducting transitions into the “pure” states of different symmetry to be mixed.