Scientists Discover New Phase of Matter That's a Song of Ice and Fire

Physicists with the U.S. Department of Energy have discovered a new phase of matter—and, with apologies to George R. R. Martin, it's something of "a song of ice and fire."

The duo from the Brookhaven National Laboratory in New York made the revelation while studying a one-dimensional model magnetic material, the copper–iridium oxide Sr₃CuIrO₆.

The new phase comes in the form of a pattern of electron spins—half of which are highly ordered, or "cold", and the rest of which are highly disordered, or "hot," hence the nickname of "half-ice, half-fire" given to it by the researchers.

"Finding new states with exotic physical properties—and being able to understand and control the transitions between those states—are central problems in the fields of condensed matter physics and materials science," said paper author Weiguo Yin in a statement. "Solving those problems could lead to great advances in technologies like quantum computing and spintronics."

"Half-ice, half-fire" is actually the hidden twin of the "half-fire, half-ice" phase the duo described in Sr3CuIrO6 early in 2024, after more than a decade studying the phase behaviors of the ferromagnetic material.

Induced by the application of an external magnetic field, the previously identified "half-fire, half-ice" state sees disordered, "hot" spins on the copper atoms, and fully ordered, "cold" spins on the iridium sites in the material.

"But despite our extensive research, we still didn't know how this state could be utilized," said paper co-author Alexei Tsvelik.

This, he added, was "especially because it has been well known for one century that the one-dimensional Ising model—an established mathematical model of ferromagnetism that produces the half-fire, half-ice state—does not host a finite-temperature phase transition."

"We were missing pieces of the puzzle."

In the new study, the researchers have shown that the "forbidden" phase transition can be achieved only at a very narrow range of temperatures.

And thus, when the "hot" and "cold" spins switch position, the "half-fire, half ice" phase becomes instead its "half-ice, half-fire" counterpart.

Such ultrasharp phase switching with giant changes in entropy could be applied in future refrigeration technologies, the team explained.

The phenomenon could also be used to develop a new type of data storage, in which the phases themselves act as bits of information

"We suggest that our findings may open a new door to understanding and controlling phases and phase transitions in certain materials," said Tsvelik.

Yin added: "Next, we are going to explore the fire–ice phenomenon in systems with quantum spins and with additional lattice, charge and orbital degrees of freedom."

He concluded: "The door to new possibilities is now wide open."

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about physics? Let us know via science@newsweek.com.

Reference

Yin, W., Roth, C. R., & Tsvelik, A. M. (2024). Spin frustration and an exotic critical point in ferromagnets from nonuniform opposite $g$ factors. Physical Review B, 109(5). https://doi.org/10.1103/PhysRevB.109.054427

Yin, W., & Tsvelik, A. M. (2024). Phase Switch Driven by the Hidden Half-Ice, Half-Fire State in a Ferrimagnet. Physical Review Letters, 133(26). https://doi.org/10.1103/PhysRevLett.133.266701