Microscopic Insights into London Penetration Depth: Application to CeCoIn$^{}_{5}$

TL;DR

This paper develops a microscopic theoretical framework for magnetic penetration depth in superconductors, emphasizing the roles of band structure, Fermi surface topology, and order parameter symmetry, with applications to CeCoIn5 revealing nodal $d_{x^2-y^2}$ symmetry.

Contribution

It introduces a comprehensive microscopic formulation of $ ext{λ}(T)$ considering band structure and symmetry, applied specifically to CeCoIn5 to analyze local and non-local magnetic responses.

Findings

Evidence of nodal $d_{x^2-y^2}$ symmetry in CeCoIn5

Alignment with London-type superconductivity characteristics

Implications for future experimental investigations

Abstract

We propose a comprehensive theoretical formulation of magnetic penetration depth, $\lambda(T)$, based on the microscopic calculations for a general superconducting gap symmetry. Our findings admit the significant role of band structure and Fermi surface topology together with the symmetry of superconducting order parameter. We employ our findings pertaining to the heavy-fermion superconductor CeCoIn$_5$ to explore both local and non-local behaviors in response to an external magnetic field across varying temperatures. Our calculations in the low-temperature regime offer compelling macroscopic evidence of the nodal character within the superconducting state with $d_{x^2-y^2}$ symmetry. Furthermore, our findings align with the characteristics of London-type superconductivity, holding significant implications for upcoming experiments.