It's not every day that a new state of matter is discovered in quantum physics, the branch of science that studies the behaviour of atomic and subatomic particles to better comprehend their features. However, an international team of researchers has done just that. The team has discovered a new quantum state of matter for the first time. In a magnetic substance named Ce2Zr2O7, which is made up of cerium, zirconium, and oxygen, the team discovered a “quantum spin liquid ground state”. Spin is an important feature in quantum physics that influences electron ordering.
Spin causes a disorganised structure comparable to that of molecules in some materials, and, hence, the term “spin liquid”. Because the direction of spin continues to fluctuate as the material cools, spin liquids remain disorganised. This is alike stabilising in a solid state as in a conventional magnet, where all the spins are aligned.
The research was conducted by Andrea Bianchi, a physics professor at the University of Montreal, and his students Avner Fitterman and Jeremi Dudemaine. The researchers documented their study in the scientific journal Physical Review X.
As the material's temperature rises, it gets more disorganised. Spin liquids, on the other hand, have the property of remaining disorganised even when cooled to absolute zero (–273°C / –459.67°F).
Unlike traditional magnets, electrons in quantum spin liquids are arranged in a triangle lattice and form a “menage a trois” with strong turbulence disrupting their order. There is no magnetic order as a result of the entangled wave function. In contrast, electron spins are all orientated in the same direction in traditional magnets, forming a ferromagnetic phase.
Bianchi stated that the electron spins cannot align when a third electron is introduced because the two surrounding electrons must always have opposing spins, causing magnetic frustration. Even at very low temperatures, this generates excitations that preserve spin disorder and thus, the liquid state.
Talking about Ce2Zr2O7, Bianchi said that though the existence of this compound was known, their breakthrough was creating it in a uniquely pure form. The researchers used samples melted in an optical furnace to produce a near-perfect triangular arrangement of atoms and then checked the quantum state.
Bianchi added that their results revealed an overlapping particle function—therefore no Bragg peaks—clearly indicating the absence of classical magnetic order. They also noticed a spin distribution with constantly changing directions, which is typical of spin liquids and magnetic frustration. This shows that at low temperatures, the material produced behaves like a real spin liquid.
Scientists confirmed that they were witnessing a never-before-seen quantum state after verifying their observations with computer simulations.
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