Terahertz spectroscopy evidence of possible 40 K superconductivity in rhenium-doped strontium ruthenates

TL;DR

This study presents evidence of possible high-temperature superconductivity at 40 K in rhenium-doped strontium ruthenates, based on terahertz spectroscopy and other measurements, with surface effects indicating higher critical temperatures.

Contribution

First demonstration of potential 40 K superconductivity in rhenium-doped strontium ruthenates using terahertz spectroscopy and comprehensive experimental analysis.

Findings

Indications of superconductivity at 40 K in doped strontium ruthenates

Higher critical temperature observed on the surface than in the bulk

Structural heterogeneity and lattice changes identified

Abstract

Strontium ruthenates have many similarities with copper oxide superconductors and are of particular interest for the investigation of the mechanisms and conditions which lead to high-temperature superconductivity. We report here on multiple experimental indications of superconductivity with onset at 40 K in strontium ruthenate doped by rhenium and selenium with chlorine used as the flux. The main experimental evidence arises from terahertz spectroscopy of this material followed by AC and DC magnetization, as well as measurements of its heat capacity and magnetoresistance. Structural and morphological studies revealed the heterophase nature of this polycrystalline material as well as the changes of lattice parameters relative to the original phases. Experimental data show a higher critical temperature on the surface compared to that of the bulk of the sample.