Quantization of diamagnetic current in a superconducting ring with the Josephson point contact

TL;DR

This paper demonstrates that the critical diamagnetic current in a superconducting ring with a Josephson contact exhibits a strictly periodic dependence on magnetic field strength, explained through an interference model of quantized circulating currents.

Contribution

It provides experimental evidence and a theoretical explanation for the quantization and periodicity of diamagnetic current in superconducting rings with Josephson point contacts.

Findings

Critical diamagnetic current is a periodic function of magnetic field.

The periodicity is explained by interference and quantization of circulating currents.

The microstructure of the contact does not affect the periodic dependence.

Abstract

It was established experimentally that a critical value of the diamagnetic current, excited by an external magnetic field in a superconducting ring (with an inductance of about ~ 10^-6 H) with a Nb-Nb clamping point contact having the Josephson contact properties is a strictly periodic function of field strength, despite the complex microstructure of the clamping contact. The reasons of the periodic dependence are discussed on a basis of the interference model of diamagnetic current and quantized values of the circulating current in the microinterferometer formed by the clamping contact.