Magnetic-field-induced finite-size effect in the high-temperature superconductor YBa2Cu3O7-a comparison to rotating superfluid 4 He

TL;DR

This study demonstrates that strong magnetic fields cause a finite-size effect in YBa2Cu3O7-d, broadening the superconducting transition by disrupting phase coherence without significantly affecting pairing, similar to effects observed in rotating superfluid 4 He.

Contribution

It provides experimental evidence of a magnetic-field-induced finite-size effect in high-temperature superconductor YBa2Cu3O7-d, linking it to vortex-vortex length scales and comparing it to superfluid 4 He.

Findings

Magnetic fields induce broadening of the superconducting transition.

The primary effect is the destruction of phase coherence.

Pairing remains insensitive to magnetic fields of around 10 T.

Abstract

The effect of strong magnetic fields (11 T) on superconductivity in YBa2Cu3O7-d is investigated using high-resolution thermal expansion. We show that the field-induced broadening of the superconducting transition is due to a finite-size effect resulting from the field-induced vortex-vortex length scale. The physics of this broadening has recently been elucidated for the closely related case of rotating superfluid 4 He [R. Haussmann, Phys. Rev. B60, 12373 (1999)]. Our results imply that the primary effect of magnetic fields of the order of 10 T is to destroy the phase coherence; the pairing, on the other hand, appears to be quite insensitive to these fields.