Experimental determination of B-T phase diagram of YBa_2Cu_3O_7-d to 150T for B perpendicular to c

TL;DR

This study maps the B-T phase diagram of YBa_2Cu_3O_7-d thin films up to 150T, revealing a transition from orbital to paramagnetic effects and identifying a 3D-2D crossover at high fields.

Contribution

The paper provides the first high-field (up to 150T) experimental phase diagram of YBa_2Cu_3O_7-d, highlighting the transition mechanisms and crossover phenomena.

Findings

Linear B_c2(T) up to 110T consistent with previous magnetization data

Transition from orbital to paramagnetic limiting at high fields

Identification of a 3D-2D crossover at 74K

Abstract

The B-T phase diagram for thin film YBa_2Cu_3O_7-d with B parallel to the superconducting layers has been constructed from GHz transport measurements to 150T. Evidence for a transition from a high T regime dominated by orbital effects, to a low T regime where paramagnetic limiting drives the quenching of superconductivity, is seen. Up to 110T the upper critical field is found to be linear in T and in remarkable agreement with extrapolation of the longstanding result of Welp et al arising from magnetisation measurements to 6T. Beyond this a departure from linear behaviour occurs at T=74K, where a 3D-2D crossover is expected to occur.