Penetration of the magnetic field into the twinning plane in the type I and II superconductors

TL;DR

This paper investigates how magnetic fields penetrate twinning planes in type I and II superconductors, revealing that low transparency planes can host Josephson-like vortices, affecting critical fields and phase diagrams.

Contribution

It introduces a model describing magnetic field penetration into twinning planes as Josephson-like vortices, linking phase diagram changes to TP transparency in superconductors.

Findings

Magnetic field can energetically favor penetration into low-transparent twinning planes.

Twinning planes act as Josephson junctions with vortex penetration.

Phase diagrams are significantly altered by magnetic field effects near the twinning plane.

Abstract

It is demonstrated that in the type I and II superconductors with low-transparent twinning planes (TP) the penetration of external parallel magnetic field into the region of the twinning plane can be energetically favorable. In the type I superconductors the twinning planes become similar to Josephson junctions and the magnetic field penetrates into the center of the TP in the form of soft Josephson-like vortices. This leads to increase in the critical magnetic field values. The corresponding phase diagram in the parameter plane "temperature - magnetic field" essentially differs from the one obtained without taking the finite value of the magnetic field near the TP into account. Comparison between obtained phase diagrams and experimental data for different type I superconductors can allow to estimate the value of the TP transparency, which is the only fitting parameter in our theory.