Vortex glass-liquid transition and activated flux motion in an epitaxial, super-conducting NdFeAs(O,F) thin film

TL;DR

This study investigates the vortex glass-liquid transition and flux motion in a high-quality NdFeAs(O,F) thin film, revealing critical exponents and flux dynamics relevant for understanding superconducting properties.

Contribution

It provides experimental evidence of vortex glass-liquid transition in NdFeAs(O,F) thin films and analyzes flux motion with detailed critical exponents and models.

Findings

Voltage-current characteristics follow vortex-glass model

Critical exponent ν ≈ 1.35 observed

Dynamic exponent z varies from 7.8 to 9.0

Abstract

An epitaxial NdFeAs(O,F) thin film of 90 nm thickness grown by molecular beam epitaxy on MgO single crystal with Tc = 44.2 K has been investigated regarding a possible vortex glass-liquid tran-sition. The voltage-current characteristics show excellent scalability according to the vortex-glass model with a static critical exponent {\nu} of around 1.35 and a temperature-dependent dynamic exponent z increasing from 7.8 to 9.0 for the investigated temperature range. The large and non-constant z values are discussed in the frame of 3D vortex glass, thermally activated flux motion, and inhomogeneity broadening.