Fabrication of microstructured devices of the unconventional superconductor CeCoIn5 for investigations of isolated grain boundaries

TL;DR

This paper details the fabrication and analysis of grain boundary devices in the unconventional superconductor CeCoIn$_5$, revealing their structural properties and potential for quantum device applications.

Contribution

It provides a novel fabrication method for isolated grain boundary devices in CeCoIn$_5$ and investigates their structural and transport properties.

Findings

Abundance of 90° misorientation grain boundaries in CeCoIn$_5$

Transport measurements show superconducting coherence across grain boundaries

Establishes a lower bound on critical current density for grain boundaries

Abstract

Grain boundaries are critical for determining the functionality of polycrystalline materials. Here we present on the structural $\&$ transport properties of grain boundaries in the unconventional superconductor CeCoIn$_5$. We provide a detailed recipe for the fabrication of isolated grain boundary devices from of as-grown polycrystalline samples of CeCoIn$_5$. Electron backscattered diffraction imaging of polycrystalline CeCoIn$_5$ samples reveals an abundance of $90^\circ$ misorientation grain boundaries suggesting a preferential nucleation of CeCoIn$_5$ grains with 90$^\circ$ misorientation over a random distribution of grain orientations. Transport measurements across grain boundary devices establish coherence of superconductivity and allows us to establish a lower bound on the critical current density for the grain boundaries. Our work opens new possibilities for fabrication of quantum devices such as Josephson-junctions out of bulk unconventional superconducting materials.