Electron transmission in normal/heavy-fermion superconductor junctions

TL;DR

This paper investigates electron transmission and Andreev reflection at normal metal/heavy-fermion superconductor interfaces, establishing boundary conditions and showing mass enhancement does not impede electron flow, with extensions to two-fluid models.

Contribution

It provides a clear theoretical framework for electron transmission in N/HFS junctions, including boundary conditions and implications of mass enhancement effects.

Findings

Mass enhancement factors do not cause impedance at the interface.

Boundary conditions for electron wave functions are explicitly derived.

Extension to a two-fluid model applicable to CeCoIn_5 is proposed.

Abstract

The Andreev reflection between a normal metal (N) and a heavy-fermion superconductor (HFS) is studied and the boundary conditions for the electron's wave function in the two systems are established in the framework of a two band model for the HFS. Hence we show in a simple and explicit way that the mass enhancement factors in the heavy-fermion (HF) metal do not cause impedance at the N/HFS interface, in accordance with arguments previously presented. We also present an extension of the theory to a two-fluid model for the heavy-fermion, as possibly applicable to, e.g., CeCoIn_5.