First time in history! The ground state of quantum spin liquid is observed for the first time

Original title: Quantum spin liquid ground state observed for the first time

An international research team composed of scientists from the United States, Germany and Canada wrote in the latest issue of Physical Review X that they observed the "quantum spin liquid ground state" for the first time in the magnetic material Ce2Zr2O7. The latest research is expected to open up new directions for quantum computer design.

Spin is an internal property of electrons that involves rotation, and it is this that gives the material in a magnet its magnetic properties. In some materials, spin can lead to structural disorder, similar to molecules in a liquid, hence the term "spin liquid". The key characteristic of spin liquids is that they remain disordered even when cooled to absolute zero (minus 273 degrees Celsius). This is because the direction of the spins continues to fluctuate as the material cools, rather than settling down in a solid state as in a conventional magnet (where all the spins are aligned).

The researchers explained that imagine an electron as a small compass that points up or down. In a traditional magnet, the electron spins all point in the same direction, up or down, forming the so-called "ferromagnetic phase." But in a quantum spin liquid, the electrons are placed in a triangular lattice, forming a triangle, characterized by strong turbulence that disrupts their order. The result is an entangled wave function with no magnetic order.

"When you add a third electron, the electron spins can't align because the two neighboring electrons have opposite spins, which creates what we call magnetic frustration," explains Andrea Bianchi, a professor of physics at the University of Montreal and the leader of the latest research. "This ground state creates excitations that maintain the spin disorder, thus maintaining the liquid state, even at very low temperatures."

Bianchi said that Ce2Zr2O7 is a cerium-based material with magnetic properties. Scientists have previously produced this compound. The new study produced it in a unique pure form. They used samples melted in an optical furnace to produce a nearly perfect triangular atomic arrangement and then examined the quantum state. The results showed that it was this nearly perfect triangle that allowed them to create magnetic frustration in Ce2Zr2O7.

"Our measurements show that the particle functions overlap, so there is no clear sign of classical magnetic order," Bianchi said. "In addition, we observed a constantly fluctuating distribution of spin orientations, which is characteristic of spin liquids and magnetic frustration, suggesting that the material we created behaves like a true spin liquid at low temperatures."

After confirming these observations with computer simulations, the team concluded that they had indeed observed a never-before-seen quantum state - the quantum spin liquid ground state.