Crystal Growth and Characterization of HgBa2Ca2Cu3O8+{\delta} Superconductor with the Highest Critical Temperature at Ambient Pressure

TL;DR

This paper presents a new method for growing high-quality HgBa2Ca2Cu3O8+{ extdelta} single crystals, enabling detailed studies of their superconducting properties and doping control, with a record critical temperature of 133 K.

Contribution

The study introduces an original crystal growth procedure for Hg-1223 superconductors, allowing precise doping control and detailed structural characterization at ambient pressure.

Findings

Achieved high-quality single crystals with sharp superconducting transitions.

Demonstrated control over doping levels through heat treatment.

Identified structural signatures of under-doping via X-ray and Raman spectroscopy.

Abstract

We report an original procedure for the elaboration of very high quality single crystals of superconducting HgBa2Ca2Cu3O8+{\delta} mercury cuprates. These single crystals are unique with very high quality surface paving the way for spectroscopic, transport and thermodynamic probes in order to understand the hole-doped cuprate phase diagram. The superconductivity transition width of about 2 K indicates they are homogeneous. Annealing allows to optimize Tc up to Tc$^{max}$ = 133 K. We show for the first time that with adequate heat treatment, Hg-1223 can be largely under-doped and its doping level controlled. Importantly, the crystal structure was studied in detail by single crystal X-ray diffraction, and we have identified the signature of the under-doping by a detailed sample characterization and micro-Raman spectroscopy measurements.