Strongly correlated electronic superconductivity in the noncentrosymmetric Re-Os-based high/medium-entropy alloys

TL;DR

This study reports the synthesis and characterization of five new noncentrosymmetric Re-Os-based high/medium-entropy alloy superconductors, revealing their stable structure, superconducting transition temperatures, and strong electronic correlations.

Contribution

It introduces five novel Re-Os-based high/medium-entropy alloys with superconductivity and analyzes their structural and electronic properties, highlighting their stability and strong correlations.

Findings

All five alloys crystallize in a noncentrosymmetric {}-Mn-type structure.

Superconducting transition temperatures range from 4.20 K to 5.11 K.

Alloys exhibit large Kadowaki-Woods ratios indicating strong electronic correlations.

Abstract

The class of unconventional superconductors, particularly noncentrosymmetric superconductors, has been highly considered as potential materials for understanding the complex properties of quantum materials. Here, five previously unreported Re3.5Os3.5Ta0.5Hf0.5Nb3, Re3Os3Ta0.5Hf0.5Nb3, Re3.5Os3.5Mo0.5Hf0.5Nb3, Re3.5Os3.5Mo0.5W0.5Nb3, and Re3Os3Mo0.5Hf0.5Nb3 Re-Os-based high/medium-entropy alloys (MEAs-HEAs) with valence electron count ranging from 6.45 to 6.81 were synthesized and investigated using x-ray diffraction, transport, magnetization, and specific heat measurements. Our analyses confirm that all five compounds crystallize in a noncentrosymmetric {\alpha}-Mn-type structure and exhibit type-II superconductivity with Tc values from 4.20 K to 5.11 K, respectively. Unexpectedly, despite being immersed in an acidic environment for one month, the structures and superconducting properties of HEAs remain stable. Our findings indicate that the Tc increases with an increasing valence electron count in MEAs-HEAs. Furthermore, these noncentrosymmetric {\alpha}-Mn-type HEA superconductors have large Kadowaki-Woods ratios (KWR), implying the presence of strong electronic correlations.