Non-destructive characterisation of dopant spatial distribution in cuprate superconductors

TL;DR

This paper introduces a non-destructive neutron imaging technique to spatially map dopant distribution in cuprate superconductors by detecting local variations in critical temperature, aiding in understanding doping inhomogeneities.

Contribution

The paper presents a novel neutron imaging method that non-destructively characterizes dopant distribution in superconductors by mapping critical temperature variations.

Findings

Successfully mapped doping inhomogeneities in LSCO crystal

Method detects minor variations in critical temperature

Complementary magnetic susceptibility measurements validate results

Abstract

Proper characterisation of investigated samples is vital when studying superconductivity as impurities and doping inhomogeneities can affect the physical properties of the measured system. We present a method where a polarised neutron imaging setup utilises the precession of spin-polarised neutrons in the presence of a trapped field in the superconducting sample to spatially map out the critical temperature for the phase transition between superconducting and non-superconducting states. We demonstrate this method on a superconducting crystal of the prototypical high-temperature superconductor (La,Sr)$_2$CuO$_4$. The results, which are backed up by complementary magnetic susceptibility measurements, show that the method is able to resolve minor variations in the transition temperature across the length of the LSCO crystal, caused by inhomogeneities in strontium doping.