Magnetic screening in proximity effect Josephson-junction arrays

TL;DR

This paper investigates how magnetic field modulation of sheet inductance in Josephson-junction arrays diminishes at low temperatures, revealing limitations of the XY model in describing the system's behavior.

Contribution

It demonstrates the inadequacy of the XY model for low-temperature behavior of JJAs and highlights the system's transition beyond the weak screening limit.

Findings

Magnetic modulation vanishes at low temperatures

XY model does not fully describe low-temperature behavior

System exceeds the weak screening limit

Abstract

The modulation with magnetic field of the sheet inductance measured on proximity effect Josephson-junction arrays (JJAs) is progressively vanishing on lowering the temperature, leading to a low temperature field-independent response. This behaviour is consistent with the decrease of the two-dimensional penetration length below the lattice parameter. Low temperature data are quantitatively compared with theoretical predictions based on the XY model in absence of thermal fluctuations. The results show that the description of a JJA within the XY model is incomplete and the system is put well beyond the weak screening limit which is usually assumed in order to invoke the well known frustrated XY model describing classical Josephson-junction arrays.