Nonlocal effects on penetration depth of FFLO d-wave superconductors

TL;DR

This paper calculates how nonlocal effects influence the penetration depth in FFLO d-wave superconductors under magnetic fields, revealing temperature and magnetic field dependencies and differences based on field orientation.

Contribution

It introduces a detailed analysis of nonlocal effects on penetration depth in FFLO d-wave superconductors, including the impact of magnetic field orientation and temperature.

Findings

Penetration depth varies as T^3 below T* for parallel magnetic fields.

Nonlocal effects cause a T^4 dependence at high temperatures.

Magnetic field dependence differs with and without Q dependence.

Abstract

The penetration depth of FFLO d-wave superconductors is calculated, in presence of additional magnetic field for both parallel and perpendicular to the internal FFLO magnetic field, when the nonlocal effects are dominated. The generalized Gorkov equations have been used to obtain the linearized response kernel. It is shown that extra term added to total kernel with no spatially gap is proportional to the momentum of FFLO Cooper pairs, Q. For the case parallel to the internal FFLO magnetic field, below a crossover temperature T*, it is shown that Lambda(T)-Lambda(0) is proportional to T^3 for both specular reflecting and diffusive boundary. It is noted that both terms in penetration depth with and without Q dependence have the same temperature dependence but magnetic field dependence are different(the terms without and with Q dependence are proportional to 1/h' and 1/(h'^2) respectively). Also nonlocal effect on penetration depth of FFLO state in reign T>>T* obtains temperature dependence T^4. Furthermore, when external magnetic test-field is perpendicular to internal FFLO magnetic field, it is shown that nonlocal effects on penetration depth give the same Q and temperature dependence as the parallel case but with different internal and additional magnetic field dependences.