Characterizing the order parameter of high-temperature cuprate superconductivity in the a-b plane*

Understanding superconductivity at high temperatures has been an evasive scientific hurdle. This talk outlines efforts taken to exploit recent advances in nanofabrication through helium focused ion beam microscopy for the advancement of scientific and technical understanding of high-transition temperature superconductivity. Ion irradiation incident on cuprate materials undergoes a metal to insulator transition and may be directed to create a Josephson junction with clean interfaces and a barrier on the dimensional scale of the coherence length. These Josephson junctions are directly written and offer a novel way to characterize cuprate superconductors in their a-b plane regarded to be the site of superconductivity in these materials. Differential conductance measurements are taken across these junctions to characterize the density of states within the a-b plane. A practical order parameter of cuprate superconductivity is defined. Measurements of the order parameter are taken at variable angles to help determine the practical pairing symmetry. Measurements indicate a significant s-wave component mixed with no more than 30% of the prominent d-wave symmetry.