Paramagnetic and diamagnetic states in two-dimensional Josephson-junction arrays

TL;DR

This paper investigates the paramagnetic and diamagnetic states in two-dimensional Josephson-junction arrays, using simulations to identify signatures of pi-junctions that could distinguish them from conventional junctions.

Contribution

The study introduces a simulation-based method to differentiate pi-junctions from conventional junctions through symmetry-breaking signatures.

Findings

Pi-junctions cause measurable symmetry breaking.

Differences between conventional and pi-junction arrays can be identified.

Simulations suggest signatures for detecting pi-junctions in experiments.

Abstract

Many experiments on high-temperature superconductors have shown paramagnetic behavior when the sample is field cooled. The paramagnetism was first attributed to a d-wave order parameter creating pi-junctions in the samples. However, the same effect was later discovered in traditional low-temperature superconductors and conventional Josephson-junction arrays which are s-wave. By simulating both conventional and mixed pi/conventional Josephson-junction arrays we determine that differences exist which may be sufficient to clearly identify the presence (or absence) of pi-junctions. In particular the pi-junctions cause a symmetry breaking providing a measurable signature of their presence in sample.