In 1973, physicist and later Nobel laureate Philip W. Anderson proposed a bizarre state of matter: the quantum spin liquid (QSL). Unlike the everyday liquids we know, the QSL actually has to do with magnetism—and magnetism has to do with spin.
What makes a magnet? It was a long-lasting mystery, but today we finally know that magnetism arises from a peculiar property of sub-atomic particles, like electrons. That property is called "spin," and the best—yet grossly insufficient—way to think of it is like a child's spinning-top toy.
What is important for magnetism is that spin turns every one of a material's billions of electrons into a tiny magnet with its own magnetic "direction" (think north and south pole of a magnet). But the electron spins aren't isolated; they interact with each other in different ways until they stabilize to form various magnetic states, thereby granting the material they belong to magnetic properties.
In a conventional magnet, the interacting spins stabilize, and the magnetic directions of each electron align. This results in a stable formation.
But in what is known as a "frustrated" magnet, the electron spins can't stabilize in the same direction. Instead, they constantly fluctuate like a liquid—hence the name "quantum spin liquid."
What is exciting about QSLs is that they can be used in a number of applications. Because they come in different varieties with different properties, QSLs can be used in quantum computing, telecommunications, superconductors, spintronics (a variation of electronics that uses electron spin instead of current), and a host of other quantum-based technologies.
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