40K at Ambient Pressure, 73K at 160,000 Atmospheres — Two Separate Types of Superconductivity Connected in a Single Thin Film

Explanation

Superconductivity is a phenomenon in which electrical resistance drops to zero when a material is cooled below a certain temperature. If resistance is zero, electricity lost as heat during transmission disappears, so practical application would change the way we use energy. The problem is that "the temperature is very low," and researchers continue to search for materials that become superconducting at even slightly higher temperatures.

Nickel oxides (compounds composed of nickel and oxygen) are a promising candidate in this search. However, research on this group of materials had been split into two until now. One line of research showed that applying ultra-high pressure on the order of 200,000 atmospheres induces superconductivity at high temperatures. The other line involved making thin films that become superconducting at ambient pressure. Even though they are the same nickel oxides, separate samples and separate experiments were conducted on the high-pressure side and the ambient-pressure side, and it was unknown whether the two shared the same mechanism.

On August 20, 2026, a joint research group from the University of Tokyo, RIKEN, and Tohoku University announced that they had connected these two on a single sample. They created a strained bilayer nickel oxide thin film. This thin film becomes superconducting at ambient pressure at about 40 kelvin (about minus 233 degrees Celsius), and when 16 gigapascals (about 160,000 atmospheres) of pressure was applied, the temperature at which it becomes superconducting (the transition temperature) rose to a maximum of 73 kelvin (about minus 200 degrees Celsius).

This is the first time that high-pressure superconductivity and ambient-pressure superconductivity in the same material system have been observed continuously in a thin-film sample. The research group combined measurements under strong magnetic fields with measurements under high pressure to investigate the superconducting properties of the thin film.

Why does this "connection" matter? The fact that two phenomena, previously seen only in separate experiments, changed continuously on the same sample strongly suggests that they are not different mechanisms but two ends of a single mechanism. If there is a single mechanism, it becomes possible to consider, as a matter of design, "what should be changed instead of pressure to raise the transition temperature." This opens a path toward creating materials with high transition temperatures without using ultra-high-pressure equipment.

A pressure of 160,000 atmospheres corresponds to conditions found several hundred kilometers deep inside the Earth. Bringing this closer to everyday pressure is the goal of this field.

The paper was published in the British academic journal Nature Materials (DOI: 10.1038/s41563-026-02695-3).

Source: RIKEN, "Elucidating the connection between high-temperature superconductivity appearing at ambient pressure and at high pressure" (August 20, 2026)
https://www.riken.jp/press/2026/20260820_1/index.html