On the nature of the reentrant effect in susceptibility of mesoscopic cylindrical samples

TL;DR

This paper proposes a theoretical explanation for the reentrant susceptibility effect in mesoscopic cylindrical NS samples, emphasizing the role of Andreev levels and their periodic alignment with the chemical potential under varying magnetic fields or temperature.

Contribution

It introduces a theory based on Andreev level properties to explain the reentrant susceptibility effect in mesoscopic cylindrical NS samples.

Findings

Susceptibility sharply increases when Andreev levels align with the chemical potential.

The reentrant effect is linked to degeneracy of quantum levels under magnetic field or temperature changes.

The theory explains the periodic nature of the susceptibility enhancement.

Abstract

Theory of the reentrant effect in susceptibility of mesoscopic cylindrical NS samples is proposed, which is essentially based on the properties of the Andreev levels. The specific feature of the quantum levels of the structure is that in a varying magnetic field (or temperature) each level periodically comes into coincidence with the chemical potential of the metal. As a result, the state of the system becomes strongly degenerate and the amplitude of the paramagnetic contribution to the susceptibility increases sharply.