Record-High Superconductivity in Niobium-Titanium Alloy.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Superconductivity

Background:

• Niobium-titanium (Nb-Ti) alloys are crucial commercial superconductors.
• Understanding the behavior of superconductors under extreme conditions is vital for technological advancement.

Purpose of the Study:

• To investigate the superconducting properties of a commercial niobium-titanium alloy under high pressure.
• To determine the critical parameters like superconducting transition temperature (T_C) and critical magnetic field (H_C2) at ultra-high pressures.

Main Methods:

• Applying extreme hydrostatic pressure up to 261.7 GPa to a commercial niobium-titanium alloy.
• Measuring the electrical resistance to identify the superconducting transition.
• Determining the superconducting transition temperature (T_C) and critical magnetic field (H_C2) at various pressures.

Main Results:

• Superconductivity was observed to persist from ambient pressure up to a record 261.7 GPa.
• The superconducting transition temperature (T_C) increased from ≈9.6 K to ≈19.1 K at 261.7 GPa.
• The critical magnetic field (H_C2) at 1.8 K enhanced from 15.4 T to 19 T under ultra-high pressure.
• A significant volume reduction of 45% occurred without a structural phase transition.

Conclusions:

• The niobium-titanium alloy exhibits extraordinary superconductivity under extreme pressure, setting new records for T_C and H_C2 in transition metal alloys.
• These findings expand the understanding of this commercial superconductor and contribute to elucidating the superconducting mechanism under pressure.