In-Field Critical Current of Type-II Superconductors Caused by Strain from Nano-scale Columnar Inclusions

TL;DR

This paper investigates how nano-scale columnar inclusions in type-II superconductors induce strain that enhances critical current by acting as vortex pinning centers, with implications for superconductor design.

Contribution

It provides a linear elasticity analysis showing how nano-rod inclusions create shear strain that improves vortex pinning and critical current in superconducting films.

Findings

Nano-rod inclusions induce shear strain in the superconductor matrix.

Strain from inclusions acts as a collective vortex pinning mechanism.

Growth of inclusions can be metastable if softer than the matrix.

Abstract

The results of a linear elasticity analysis yields that nano-rod inclusions aligned along the c axis of a thin film of YBa2Cu3O{7-delta}, such as BaZrO3 and BaSnO3, squeeze that matrix by pure shear. The sensitivity of the superconducting critical temperature in that material to the latter implies that the phase boundary separating the nano-rod inclusion from the superconductor acts as a collective pinning center for the vortex lattice that appears in external magnetic field. A dominant contribution to the in-field critical current can result. The elasticity analysis also finds that the growth of nano-rod inclusions can be weakly metastable when the inclusion is softer than the matrix.