Vortex State of Tl$_2$Ba$_2$CuO$_{6+\delta}$ via $^{205}$Tl NMR at 2 Tesla

TL;DR

This study uses $^{205}$Tl NMR to investigate the vortex state in an overdoped Tl$_2$Ba$_2$CuO$_{6+ ext{delta}}$ superconductor at 2 Tesla, revealing vortex lattice behavior, coexistence of vortex solid and liquid, and vortex melting without antiferromagnetic order at cores.

Contribution

First NMR investigation of vortex states in overdoped Tl$_2$Ba$_2$CuO$_{6+ ext{delta}}$ at 2 Tesla, identifying vortex lattice imperfections and phase transitions.

Findings

Observed an imperfect vortex lattice (Bragg glass) at 5 K.

Detected coexistence of vortex solid and liquid phases between 10 and 60 K.

Identified vortex melting between 65 and 85 K.

Abstract

We report a $^{205}$Tl NMR study of vortex state for an aligned polycrystalline sample of an overdoped high-$T_c$ superconductor Tl$_2$Ba$_2$CuO$_{6+\delta}$ ($T_{c}\sim$85 K) with magnetic field 2 T along the c axis. We observed an imperfect vortex lattice, so-called Bragg glass at $T$=5 K, coexistence of vortex solid with liquid between 10 and 60 K, and vortex melting between 65 and 85 K. No evidence for local antiferromagnetic ordering at vortex cores was found for our sample.