Thermodynamic relations for the Cooper pair's momentum in helical superconductors

TL;DR

This paper introduces two thermodynamic relations that enable precise measurement of the Cooper pair's center-of-mass momentum in helical superconductors, facilitating better exploration of noncentrosymmetric superconductors.

Contribution

The paper proposes novel thermodynamic relations linking the Cooper pair momentum to magnetic field variations and phase transition behavior in helical superconductors.

Findings

Relation between COM momentum change and magnetic field variation.

Detection of COM momentum jump via phase transition slope.

Enhanced ability to explore noncentrosymmetric superconductors.

Abstract

Two thermodynamic relations are proposed for the exact measurement of the center-of-mass (COM) momentum of the Cooper pairs in helical superconductors. The first relation concerns the constraint on the change in the COM momentum in response to the variation in the magnetic field, which is linked to the superconducting Edelstein effect. The second relation is related to a first-order phase transition, showing that the jump of the COM momentum can be measured from the slope of the transition line on the phase diagram, where the supercurrent is used as a control parameter. These relations solve the difficulty of detecting the momentum, enabling broader and more precise exploration of noncentrosymmetric superconductors.