Two scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have discovered a new phase of matter while studying a model system of a magnetic material.
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The phase is a never-before-seen pattern of electron spins—the tiny “up” and “down” magnetic moments carried by every electron. It consists of a combination of highly ordered “cold” spins and highly disordered “hot” spins, and it has thus been dubbed “half ice, half fire.” The researchers discovered the new phase while studying a one-dimensional model of a type of magnetic material called a ferrimagnet.
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They describe the discovery in a paper published in early 2024.
But the full story goes back to 2012, when Yin and Tsvelik were part of a multi-institutional collaboration, led by Brookhaven physicist John Hill, that was studying Sr3CuIrO6, a magnetic compound of strontium, copper, iridium, and oxygen. This research led to two papers, an experiment-driven study in 2012 and a theory-driven study in 2013, both published in PRL.
Yin and Tsvelik continued to look into the phase behaviors of Sr3CuIrO6 and, in 2016, found the “half-fire, half-ice” phase. In this state, which is induced by a critical external magnetic field, the “hot” spins on the copper sites are fully disordered on the atomic lattice and have smaller magnetic moments, while the “cold” spins on the iridium sites are fully ordered and have larger magnetic moments. That work was published in Physical Review B.
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https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.054427
https://phys.org/news/2025-03-ice-physicists-phase-magnetic-material.html