Record High Tc Element Superconductivity Achieved In Titanium

TL;DR

This study reports record-high Tc superconductivity in titanium under high pressure, revealing unconventional mechanisms and strong d-electron contributions, challenging traditional electron-phonon theories.

Contribution

It demonstrates high Tc superconductivity in titanium at high pressures, highlighting unconventional mechanisms and strong d-electron involvement, which contrasts with existing theoretical predictions.

Findings

Superconductivity observed up to 20 K at 108-240 GPa

Maximum Tc^onset above 26 K and Tc^zero of 21 K

High upper critical field estimated at 32 Tesla

Abstract

It is challenging to search for high Tc superconductivity (SC) in transition metal elements wherein d electrons are usually not favored by conventional BCS theory. Here we report discovery of surprising SC up to 310 GPa with Tc above 20 K in wide pressure range from 108 GPa to 240 GPa in titanium. The maximum Tc^onset above 26 K and zero resistance Tc^zero of 21 K are record high values hitherto achieved among element superconductors. The Hc2(0) is estimated to be about 32 Tesla with coherence length 32 angstrom. The results show strong s-d transfer and d-band dominance, indicating correlation driven contributions to high Tc SC in dense titanium. This finding is in sharp contrast to the theoretical predications based on pristine electron-phonon coupling scenario. The study opens a fresh promising avenue for rational design and discovery of high Tc superconductors among simple materials via pressure tuned unconventional mechanism.