Flux Line Lattices in Artificially Layered Superconductors

TL;DR

This paper investigates how artificially layered structures influence flux line lattices in superconductors, revealing field-dependent transitions, alignment locking effects, and implications for the shear modulus, supported by experimental comparisons.

Contribution

It provides a detailed analysis of flux line lattice behavior in layered superconductors, highlighting how periodic potentials affect lattice alignment and transitions.

Findings

Sequential flux entry with magnetization jumps at low fields

Transitions between differently aligned lattice states occur with increasing field

Periodic potential enhances lattice alignment locking

Abstract

The flux line lattice of superconductors has been investigated when there exists a periodicity in the underlying system, such as can occur in artificially layered structures. For small fields parallel to the layers the flux lines enter the sample in sequential rows, with the possibility of jumps in the magnetization as new rows are created. As the field is increased these discontinuities gradually decrease, but there still exist transitions between states that are aligned differently to the periodic direction. Increasing the magnitude of the periodic potential reduces the competition between differently aligned lattices and tends to lock in one particular alignment. The effect of transitions on the shear modulus is also discussed and related to the experiments of Theunissen et al.