Vortex-glass phase transition and superconductivity in an under- doped (Ba,K)Fe2As2 single crystal

TL;DR

This study investigates the vortex-glass phase transition in an under-doped (Ba,K)Fe2As2 superconductor, revealing a vortex-glass transition up to 9 T and detailing the vortex phase diagram with critical exponents and transition temperatures.

Contribution

It provides the first detailed vortex phase diagram for under-doped (Ba,K)Fe2As2, demonstrating vortex-glass transition behavior and critical exponents in high magnetic fields.

Findings

Vortex-glass transition observed up to 9 T.

Critical exponents z=4.1 and v=1 consistent across fields.

Vortex phase diagram constructed based on Tg and Hc2.

Abstract

Measurements of magnetotransport and current-voltage (I-V) characteristics up to 9 T were used to investigate the vortex phase diagram of an under-doped Measurements of magnetotransport and current-voltage (I-V) characteristics up to 9 T were used to investigate the vortex phase diagram of an under-doped (Ba,K)Fe2As2 single crystal with Tc=26.2 K. It is found that the anisotropy ratio of the upper critical field Hc2 decreases from 4 to 2.8 with decreasing temperature from Tc to 24.8 K. Consistent with the vortex-glass theory, the I-V curves measured at H=9 T can be well scaled with the vortex-glass transition temperature of Tg=20.7 K and critical exponents z=4.1 and v=1. Analyses in different magnetic fields produced almost identical critical exponent values, with some variation in Tg, corroborating the existence of the vortex-glass transition in this under-doped (Ba,K)Fe2As2 single crystal up to 9 T. A vortex phase diagram is presented, based on the evolution of Tg and Hc2 with magnetic field.