Spontaneous Flux and Magnetic Interference Patterns in 0-pi Josephson Junctions

TL;DR

This paper models spontaneous flux and magnetic interference in 0-pi Josephson junctions, revealing how junction length ratios influence flux generation and providing insights into the Josephson coupling and order parameter symmetry in YBCO.

Contribution

It presents calculations of spontaneous flux and magnetic modulation in 0-pi Josephson junctions for various length ratios, applicable to experimental systems like Pb-YBCO junctions.

Findings

Spontaneous flux occurs even in very short symmetric junctions.

Asymmetric junctions exhibit qualitatively different behavior.

Measurements can reveal the nature of Josephson coupling and order parameter symmetry.

Abstract

The spontaneous flux generation and magnetic field modulation of the critical current in a 0-pi Josephson junction are calculated for different ratios of the junction length to the Josephson penetration depth, and different ratios of the 0-junction length to the pi-junction length. These calculations apply to a Pb-YBCO c-axis oriented junction with one YBCO twin boundary, as well as other experimental systems. Measurements of such a junction can provide information on the nature of the c-axis Josephson coupling and the symmetry of the order parameter in YBCO. We find spontaneous flux even for very short symmetric 0-pi junctions, but asymmetric junctions have qualitatively different behavior.