Observation of Single Vortices Condensed into a Vortex-Glass Phase by Magnetic Force Microscopy

Abstract

A low temperature magnetic force microscope has been applied to spatially resolve single vortices in an epitaxially grown YB${\mathrm{a}}_{2}$C${\mathrm{u}}_{3}$ ${\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ thin film at 77 K. A disordered vortex arrangement is observed, and the vortices are strongly pinned. The observed phase is expected to be truly superconducting due to strong pinning.