Point Contact Spectra on YBa$_2$Cu$_3$O$_{7-x}$/La$_{0.7}$Ca$_{0.3}$MnO$_3$ bilayers

TL;DR

This study investigates the conductance properties of point contact junctions between a normal metal tip and YBCO/LCMO bilayers, revealing zero bias conductance peaks and effects of spin polarization on superconducting features.

Contribution

It provides new insights into the conductance spectra and spin polarization effects in YBCO/LCMO bilayers using point contact spectroscopy.

Findings

Zero bias conductance peak observed due to Andreev bound states

Depressed zero bias peak with increasing temperature

Reduced superconducting energy gap linked to spin polarization

Abstract

We present conductance characteristics of point contact junctions realized between a normal Pt-Ir tip and YBa$_2$Cu$_3$O$_{7-x}$/La$_{0.7}$Ca$_{0.3}$MnO$_3$ (YBCO/LCMO) bilayers. The point contact characteristics show a zero bias conductance peak, as a consequence of the formation of Andreev bound states at the YBCO Fermi level. The temperature evolution of the spectra reveals a depressed zero bias peak and a reduced superconducting energy gap, both explainable in terms of spin polarization effects due to the LCMO layer.