Meservey-Tedrow-Fulde effect in a quantum dot embedded between metallic and superconducting electrodes

TL;DR

This paper investigates the Meservey-Tedrow-Fulde effect in a quantum dot system, demonstrating how magnetic fields influence tunneling conductance and in-gap states, revealing Zeeman splitting and hyperfine structures relevant to Kondo resonance detection.

Contribution

It introduces a theoretical analysis of the Meservey-Tedrow-Fulde effect in quantum dots coupled to metallic and superconducting electrodes, highlighting magnetic field effects on conductance and subgap states.

Findings

Zeeman splitting observed near gap edges in differential conductance

Magnetic field induces hyperfine structure in in-gap Andreev states

Signatures of Kondo resonance affected by magnetic field modifications

Abstract

Magnetic field applied to the quantum dot coupled between one metallic and one superconducting electrode can produce a similar effect as has been experimentally observed by Meservey, Tedrow and Fulde [Phys. Rev. Lett. 25, 1270 (1970)] for the planar normal metal -- superconductor junctions. We investigate the tunneling current and show that indeed the square root singularities of differential conductance exhibit the Zeeman splitting near the gap edge features V = +/- Delta/e. Since magnetic field affects also the in-gap states of quantum dot it furthermore imposes a hyperfine structure on the anomalous (subgap) Andreev current which has a crucial importance for a signature of the Kondo resonance.