New exotic state of matter in candidate material for quantum computers

An illustration of the crystal structure of ruthenium trichloride showing the simple honeycomb lattice of ruthenium ions and chlorine ions. The twisted octahedra formed by chlorine around the electron spin of each ruthenium atom are mirror images of each other. This twist is key to the compound's unusual behavior, which is evidence that it may contain an example of a quantum spin liquid. Credit: Courtesy of Arkady Shekhter/ National High Magnetic Field Laboratory

Scientists working at the Florida State University have found evidence for a quantum spin liquid, a state of matter that is promising as a building block for the quantum computers of tomorrow.

The team discovered the exciting behavior while studying the so-called electron spins in the compound ruthenium trichloride at high temperatures and in high magnetic fields. They showed that electron spins interact across the material, effectively lowering the overall energy. This type of behavior which is consistent with a quantum spin liquid.

Spin liquids, first theorized in 1973, remain something of a mystery. Despite some materials showing promising signs for this state of matter, it is extremely challenging to definitively confirm its existence. However, there is great interest in them because scientists believe they could be used for the design of smarter materials in a variety of applications, such as quantum computing.

In simple terms, electrons can be thought of as spinning on an axis, like a top, oriented in some direction. In magnetic materials, these spins align with one another, either in the same or opposite directions. Called magnetic ordering, this behavior can be induced or suppressed by temperature or magnetic field. Once the magnetic order is suppressed, more exotic states of matter could emerge, such as quantum spin liquids.

The paper has been published in the journal Nature Physics.

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