Phase diagrams of singlet superconducting states with mixed symmetry

TL;DR

This paper investigates the phase diagrams of singlet superconducting states with mixed symmetry, revealing the formation of mixed $s+id$ states and phase transitions between pure and mixed states within a single-band model.

Contribution

It provides a detailed analysis of the phase diagrams for singlet superconducting states with mixed symmetry, including the conditions for $s+id$ pairing and temperature-induced phase transitions.

Findings

Mixed $s+id$ pairing state forms between pure $s$- and d-wave states.

Temperature phase transitions occur between pure and mixed pairing states.

Phase diagrams depend on ratios of electron transfer integrals.

Abstract

The competition between the singlet superconducting states with $s$- and d-wave symmetry of the order parameter is studied within a single-band model with nearest-neighbor attractive interaction. The zero- and finite-temperature ground state phase diagrams are constructed for different ratios between the nearest- and next-nearest-neighbor electron transfer integrals. The mixed $s+id$ pairing state is shown to form in the intermediate region between $s$- and d-waves. The temperature phase transitions between the pure and the mixed pairing state are found.