An ordinary wire heats up when current flows through it. A superconductor doesn't. But almost all known superconductors require either very low temperatures or enormous pressures, like those deep inside planets. Scientists have long searched for a material that avoids these extremes.
In the new work, they took a compound of lithium, copper, and hydrogen — Li3CuH4. Inside it, there are two "layers" with different personalities. One is like table salt: lithium and hydrogen atoms hold onto each other via electrical attraction, but on its own, such a lattice is fragile. The other is like a steel mesh: copper and hydrogen atoms are linked by strong covalent bonds that hold the shape. This scaffold keeps the whole compound from falling apart even at relatively modest pressure — about 20 gigapascals (that's five times less than what many other hydrides need).
The key trick is that the copper scaffold doesn't just hold the structure. It also "rocks" the hydrogen atoms in a way that makes electrons hop easily between them. That's superconductivity: electrons move without resistance. As a result, the material becomes superconducting at just 39 kelvins (−234 °C) and 12 gigapascals. That's not room temperature, but it's already achievable in the lab without diamond anvils that squeeze the sample like a vice.
The idea was tested not just on one compound. They tried several metals instead of copper and found a general rule: if one layer is rigid and covalent, and the other is soft and ionic, together they give a stable superconductor at moderate pressure. It's like a recipe: you don't need the exact combination of ingredients, the principle matters — fragile and sturdy must complement each other.
A pressure of 12 gigapascals is like having 120 tons on every square centimeter. In the lab, such pressures are created with diamond anvils, but for this material, an ordinary hydraulic press is enough.