Record-High Superconductivity in Niobium-Titanium Alloy

TL;DR

This study reports record-high superconductivity in niobium-titanium alloy under ultra-high pressure, with increased transition temperature and magnetic field, expanding understanding of transition metal alloy superconductors.

Contribution

It demonstrates superconductivity persistence up to 261.7 GPa and significant enhancements in critical temperature and magnetic field, revealing new high-pressure superconducting properties of NbTi alloy.

Findings

Superconductivity persists up to 261.7 GPa.

Transition temperature increases to ~19.1 K at high pressure.

Critical magnetic field reaches 19 T at 1.8 K.

Abstract

Here we report the observation of extraordinary superconductivity in a pressurized commercial niobium-titanium alloy. We find that its zero-resistance superconductivity persists from ambient pressure to the pressure as high as 261.7 GPa, a record high pressure up to which a known superconducting state can continuously survives. Remarkably, at such an ultra-high pressure, although the ambient pressure volume is shrunk by 45% without structural phase transition, the superconducting transition temperature (TC) increases to ~19.1 K from ~9.6 K, and the critical magnetic field (HC2) at 1.8 K has been enhanced to 19 T from 15.4 T. These results set new records for both of the TC and the HC2 among all the known alloy superconductors composed of only transition metal elements. The remarkable high pressure superconducting properties observed in the NbTi alloy not only expand our knowledge on this important commercial superconductor but also are helpful for a better understanding on the superconducting mechanism.