Superconductivity from site-selective Ru doping studies in Zr$_5$Ge$_3$ compound

TL;DR

This study discovers superconductivity at 5.7K in Ru-doped Zr$_5$Ge$_3$, highlighting site-specific doping effects and suggesting potential unconventional superconductivity due to high critical fields and electron correlations.

Contribution

It demonstrates that Ru doping at the Ge site induces superconductivity in Zr$_5$Ge$_3$, revealing site-selective doping as a key factor for superconductivity in this system.

Findings

Superconductivity at 5.7K in Ru-doped Zr$_5$Ge$_3$

Superconductivity only occurs with Ru doping at the Ge site

High upper critical field suggests unconventional pairing

Abstract

Systematical doping studies have been carried out to search for the possible superconductivity in the transition metal doped Zr$_5$Ge$_3$ system. Superconductivity up to 5.7K is discovered in the Ru-doped Zr$_5$Ge$_{2.5}$Ru$_{0.5}$ sample. Interestingly, with the same Ru-doping, superconductivity is only induced with doping at the Ge site, but remains absent down to 1.8K with doping at the Zr site or interstitial site. Both magnetic and transport studies have revealed the bulk superconductivity nature for Ru-doped Zr$_5$Ge$_{2.5}$Ru$_{0.5}$ sample. The high upper critical field, enhanced electron correlation, and extremely small electron-phonon coupling, have indicated possible unconventional superconductivity in this system, which warrants further detailed theoretical and experimental studies.