Grain boundaries investigations in the unconventional superconductor CeCoIn₅

Grain boundaries (GB) investigations in superconductors can play a crucial role in quantum information sciences. In high temperature cuprate superconductors, investigations of the critical currents across GBs have provided significant insights on the symmetry of the order parameter and have been critical for the observation of spontaneously generated half-flux magnetic quanta [1,2]. Heavy fermion superconductors (HFS) host rich physics in the form of unconventional superconducting phases with nodal quasiparticles. However, unlike cuprate superconductors, there have been relatively few phase sensitive measurements of the order parameter thereby emphasizing the need for investigations of critical currents across GBs in HFS.

In this talk, I will present results on investigations of critical currents across grain boundaries in polycrystalline samples of the HFS CeCoIn₅. Electron backscatter diffraction images of well-polished polycrystalline samples reveal that grain boundaries with misorientations between 0^o and 90^o are present, with a majority being the 90^o misorientation GB. We performed critical current studies across various such misorientation GBs. Our investigations are crucial in understanding the superconducting order parameter symmetry of CeCoIn₅.



References:

1. H. Hilgenkamp and J. Mannhart, Rev. Mod. Phys. 74, 485, 2002.

2. C. C. Tsuei and J. R. Kirtley, Rev. Mod. Phys. 72, 969, 2000.