How a Nickel Impurity Turns a Superconductor into a Magnetic Tangle ⚡ экспресс
A bit of nickel was added to the layered material NbSe₂ — and it stopped being a superconductor. Instead, magnetic confusion arose: the atoms froze into a tangled pattern where each magnetic moment (a tiny magnet) points in different directions. It's like an argument where nobody wants to back down. Could such chaos give birth to something new?
Niobium diselenide is a layered material that conducts current without resistance at low temperatures. If you weave nickel atoms between its layers, like extra threads in a fabric, superconductivity vanishes. In its place, a tangled magnetic disorder appears: the nickel "magnetic arrows" can't align into a simple pattern because each neighbor demands the opposite direction. The result is a magnetic tangle — frustrated and inhomogeneous. When cooled below –250 °C, it freezes, but there's no long-range order, and its behavior depends on the direction within the layers.
Using photoemission spectroscopy, the reason was uncovered: a key point where electrons cluster shifted, suppressing superconductivity. An unexpected twist: cool it just ten degrees colder, and this tangle shows magnetic memory — it "remembers" the previous magnetization, like a frozen knot you don't want to untie. A tiny addition completely reshapes the properties, opening a path to creating materials with tailored characteristics.
🎯 Pure niobium diselenide is one of the few materials where superconductivity and periodic electron clusters coexist. Adding nickel erases both, creating magnetic disorder with its own memory.