Magnetic oscillations of critical current in intrinsic Josephson-junction stacks

TL;DR

This paper investigates magnetic oscillations of the critical current in intrinsic Josephson junction stacks, revealing size-dependent regimes and phase transitions between different lattice configurations influenced by magnetic field variations.

Contribution

It provides a detailed analysis of the crossover between different oscillation regimes and identifies the conditions for phase transitions in Josephson junction stacks.

Findings

Oscillation period depends on stack size, with two distinct regimes.

Crossover between regimes can be controlled by magnetic field.

Periodic phase transitions occur between rectangular and triangular lattice configurations.

Abstract

A key phenomenon related to the Josephson effect is oscillations of different properties of superconducting tunneling junctions with magnetic field. We consider magnetic oscillations of the critical current in stacks of intrinsic Josephson junctions, which are realized in mesas fabricated from layered high-temperature superconductors. The oscillation behavior is very different from the case of a single junction. Depending on the stack lateral size, oscillations may have either the period of half flux quantum per junction (wide-stack regime) or one flux quantum per junction (narrow-stack regime). We study in detail the crossover between these two regimes. Typical size separating the regimes is proportional to magnetic field meaning that the crossover can be driven by the magnetic field. In the narrow-stack regime the lattice structure experiences periodic series of phase transitions between aligned rectangular configuration and triangular configuration. Triangular configurations in this regime is realized only in narrow regions near magnetic-field values corresponding to integer number of flux quanta per junction.