A material that normally needs crushing pressure to become superconducting can keep that special state after the pressure is gone. In barium, the result reaches twenty-four kelvin at ordinary pressure. Pressure-induced superconductivity often occurs following a structural transition under hydrostatic pressure, but disappears after the pressure is released.

Barium becomes superconducting after changing from its original crystal structure to another structure under pressure, and its transition temperature reaches five kelvin at higher pressure. The key surprise is that barium can show much higher-temperature superconductivity even at ambient pressure.

So the material was given a different kind of treatment: it was squeezed while being twisted, introducing both compressive and sideways distortion. A useful everyday picture is kneading a piece of clay while pressing it: the pressure changes its size, while the twisting pushes parts of it in different directions and can create new internal arrangements.

That sideways distortion is important because it can generate crystal structures that support superconductivity caused by strain. The first evidence came from a magnetic measurement: a clear signal appeared at three kelvin in the treated barium. A smaller but visible signal also appeared at fourteen kelvin, and the researchers confirmed that neither signal came from the surrounding cells used during processing.

When an external magnetic field was applied, both signals shifted toward lower temperature, matching the behavior expected for superconducting transitions. The treatment was also carried out at very low temperature, and this produced a high-pressure crystal structure that remained as a partly preserved state afterward.

In that sample, magnetic shielding appeared at about twenty-four kelvin and disappeared when a stronger magnetic field was applied. Among the samples, the one treated at an operating pressure of twenty-one gigapascals reached the highest transition temperature: twenty-four kelvin at ambient pressure.

The measurements show that transition temperatures above ten kelvin appear when the treatment pressure is greater than twelve gigapascals. When the treatment pressure is between about ten and twenty gigapascals, the transition temperature reaches roughly twenty to twenty-five kelvin across that pressure range, according to panel b.

The plotted treatment pressure is PHPT, whereas the transition-temperature measurements were performed later at ambient pressure, not during high-pressure treatment. It adds the shape of the response: a broad rise and fall in transition temperature, while the superconducting portion is concentrated near the low-pressure end.

The treated material preserves two high-pressure crystal structures at ordinary temperature and pressure, and both support superconductivity better than barium’s original structure. The higher-temperature state appears only in a small fraction of the material, but its transition reaches twenty-four kelvin at ambient pressure.

The authors therefore propose this novel method as a way of developing high-transition-temperature superconductors, opening up significant opportunities for advancing electronic-property-related functionalities. The study shows that forcing barium into a distorted high-pressure structure can preserve superconductivity outside the pressure chamber.

That suggests a new way to search for useful superconducting materials without keeping them under extreme pressure.