Current states of a doubly connected superconductor with two point contacts

TL;DR

This paper experimentally investigates how current distributes in a doubly connected superconductor with two point contacts under various contact states, revealing current control and self-oscillation phenomena.

Contribution

It provides new insights into current behavior and oscillations in a DCS with point contacts, highlighting the roles of Josephson inductance and resistivity.

Findings

Current can be tuned by adjusting the current through contacts in different states.

Self-oscillations occur in the resistive state, with amplitude and frequency depending on injected current.

Parametric Josephson inductance influences the critical state and current distribution.

Abstract

The distribution of the transport current in branches of a doubly connected superconductor (DCS) with two clamping point contacts is investigated experimentally when the contacts are in the different states: (a) one or both contacts are in the critical state, (b) both are in the supercritical (resistive) state. In the state (a) the transport current frozen in the DCS and injected through one of the contacts can be increased or decreased by tuning the value and polarity of the current passing through the other contact. In the state (b), the current self-oscillations the amplitude and the frequency of which depend on the value of the injected transport current appear in the branches of the DCS. A role of the parametric Josephson inductance and resistivity of the contact in formation of its critical state and in distribution of the current in the branches of the DCS is discussed.