Superconducting Phase Domains for Memory Applications

TL;DR

This paper theoretically investigates S-F/N-sIS Josephson junctions, revealing superconducting phase domains that enable non-destructive memory readout and potential switching applications based on phase states.

Contribution

It introduces a novel understanding of phase domain formation in S-F/N-sIS junctions and proposes their use for superconducting memory devices.

Findings

Superconducting order parameter decomposes into phase domains.

Existence of two energy minima allowing bistability.

Memory states can be read non-destructively via electric current.

Abstract

In this work we study theoretically the properties of S-F/N-sIS type Josephson junctions in the frame of the quasiclassical Usadel formalism. The structure consists of two superconducting electrodes (S), a tunnel barrier (I), a combined normal metal/ferromagnet (N/F) interlayer and a thin superconducting film (s). We demonstrate the breakdown of a spatial uniformity of the superconducting order in the s-film and its decomposition into domains with a phase shift $\pi $ . The effect is sensitive to the thickness of the s layer and the widths of the F and N films in the direction along the sIS interface. We predict the existence of a regime where the structure has two energy minima and can be switched between them by an electric current injected laterally into the structure. The state of the system can be non-destructively read by an electric current flowing across the junction.