Magnetoresistance of Junctions made of Underdoped YBCO Separated by a Ga-doped YBCO Barrier

TL;DR

This study investigates the magnetoresistance behavior of underdoped YBCO-based SNS junctions with Ga-doped barriers, revealing a large positive, linearly field-dependent magnetoresistance linked to the proximity effect, and providing quasiparticle parameters.

Contribution

It demonstrates that underdoped YBCO/N/YBCO junctions do not show the long-range proximity effect seen in optimally doped YBCO, and measures quasiparticle diffusion and relaxation parameters.

Findings

Large positive, linear magnetoresistance observed.

Proximity effect in underdoped YBCO is not long-range.

Quasiparticle diffusion coefficient and relaxation time determined.

Abstract

We report magnetoresistance measurements of ramp type superconductor-normal-superconductor (SNS) junctions. The junctions consist of underdoped $YBa_{2}Cu_{3}O_y$ (YBCO) electrodes separated by a barrier of $YBa_{2}Cu_{2.6}Ga_{0.4}O_y$. We observe a large positive magnetoresistance, linear in the field. We suggest that this unusual magnetoresistance originates in the field dependence of the proximity effect. Our results indicate that in underdoped YBCO/N/YBCO SNS structures, the proximity effect does not exhibit the anomalously long range found in optimally doped YBCO structures. From our data we obtain the diffusion coefficient and relaxation time of quasiparticles in underdoped YBCO.