Vortex Flow and Transverse Flux Screening at the Bose Glass Transition

TL;DR

This study explores the vortex phase diagram in YBaCuO crystals with columnar defects, revealing a transverse Meissner effect and an intermediate flux localization regime below the melting temperature.

Contribution

It provides direct experimental evidence of the transverse Meissner effect and identifies an intermediate vortex localization regime in the Bose Glass phase.

Findings

Transverse Meissner effect observed with Hall probes.

The transition temperature Ts decreases linearly with transverse field.

Ts is significantly below the melting temperature Tm.

Abstract

We investigate the vortex phase diagram in untwinned YBaCuO single crystals with columnar defects. These randomly distributed defects, produced by heavy ion irradiation, are expected to induce a ``Bose Glass'' phase of localized vortices characterized by a vanishing resistance and a Meissner effect for magnetic fields transverse to the defect axis. We directly observe the transverse Meissner effect using an array of Hall probe magnetometers. As predicted, the Meissner state breaks down at temperatures Ts that decrease linearly with increasing transverse magnetic field. However, Ts falls well below the conventional melting temperature Tm determined by a vanishing resistivity, suggesting an intermediate regime where flux lines are effectively localized even when rotated off the columnar defects.