Interface effects in d-wave superconductor-ferromagnet junctions

TL;DR

This study investigates interface effects in d-wave superconductor-ferromagnet junctions, revealing that crossed Andreev reflection occurs only under specific domain wall conditions and is directionally dependent, with implications for superconducting spintronics.

Contribution

It demonstrates the occurrence of crossed Andreev reflection in YBa2Cu3O7-SrRuO3 junctions and its dependence on domain wall width and direction, providing new insights into interface effects in such junctions.

Findings

Crossed Andreev reflection observed only in YBa2Cu3O7-SrRuO3 junctions.

The effect is directionally dependent, occurring only in the anti-node direction.

Crossed Andreev reflection is insensitive to nm-scale interface defects.

Abstract

Measurements of the differential conductance spectra of YBa2Cu3O7-SrRuO3 and YBa2Cu3O7-La0.67Ca_0.33MnO3 ramp-type junctions along the node and anti-node directions are reported. The results are consistent with a crossed Andreev reflection effect only in YBa2Cu3O7-SrRuO3 junctions where the domain wall width of SrRuO3 is comparable with the coherence length of YBa2Cu3O7. No such effect was observed in the YBa2Cu3O7-La0.67Ca0.33MnO3 junctions, which is in line with the much larger (x10) domain wall width of La0.67Ca0.33MnO3. We also show that crossed Andreev exists only in the anti-node direction. Furthermore, we find evidence that crossed Andreev in YBa2Cu3O7 junctions is not sensitive to nm-scale interface defects, suggesting that the length scale of the crossed Andreev effect is larger than the coherence length, but still smaller than the La0.67Ca0.33MnO3's domain wall width.