Apr 05, 2025 14:00:00

What is the purpose of this new 'half ice, half fire' phase of matter?

Scientists at

Brookhaven National Laboratory , a national laboratory under the U.S. Department of Energy , have discovered a never-before-seen pattern in electron spin. In the past, a state known as 'half fire, half ice' was observed in which electron spin coexists in a highly disordered 'hot' state and a highly ordered 'cold' state. In the new study, however, they discovered that the phases can be switched to become ' half ice, half fire .'

Phase Switch Driven by the Hidden Half-Ice, Half-Fire State in a Ferrimagnet | Phys. Rev. Lett.
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.133.266701

Brookhaven Physicists Discover New Phase of Matter in a Magnetic Material | BNL Newsroom
https://www.bnl.gov/newsroom/news.php?a=122362

New 'Half-Ice, Half-Fire' Phase of Matter Found Lurking in a Magnet : ScienceAlert
https://www.sciencealert.com/new-half-ice-half-fire-phase-of-matter-found-lurking-in-a-magnet

Electron spin is a property similar to the rotation of an electron, and can be in two states: upward 'up spin' and downward 'down spin.' Since a magnetic field is generated depending on the direction of the spin, when many electrons have the same spin direction they function as a magnet. Conversely, when the spins are arranged randomly, magnetism disappears. Below is an illustration of electron spin ( PDF file ) by the Institute for Materials Research, Tohoku University.

Research into 'half fire, half ice' began in 2012. Brookhaven National Laboratory physicists Weiguo Yan and Alexei Tsverik were part of a collaborative project led by John Hill, studying a magnetic compound called 'strontium copper iridium oxide' made of strontium, copper, iridium, and oxygen. The magnetic compound contains two metals, copper and iridium, and in 2016, it was discovered that the compound has two states: the copper part has random spin directions and a small magnetic moment, while the iridium part has regular spins and strong magnetic properties.

The name 'half fire, half ice' does not refer to the actual temperature, but rather to the symmetric behavior of electron spins, like fire and ice. Scientists have used the metaphorical name 'half fire, half ice,' comparing the disordered, fragmented state of copper to a fiery fire and the ordered state of iridium to calm, cold ice.

The 'half fire, half ice' state, where order and disorder coexist, is intriguing, but despite extensive research it was unclear how it could be exploited because the structure is inoperable, and the mathematical criteria for phase shifts meant that no structural change was possible.

However, a study published by Yen and Tubelik in Physical Review Letters, a peer-reviewed journal of the American Physical Society, at the end of December 2024 showed that they had discovered a clear temperature change that completely changed the entire state. According to the paper, as they furthered their research into 'half fire, half ice,' they discovered a 'half ice, half fire' phase in which the behavior of electrons in the two different structures is swapped, and that it can be intentionally manipulated.

The structural change from 'half fire, half ice' to 'half ice, half fire' means that the phase change can be tightly controlled. The ultra-rapid phase switch is accompanied by a huge magnetic entropy change, which could make it useful in refrigeration, and could also be used as the basis for a new type of quantum information storage technology in which the phases act as bits.

'Discovering new states with unusual 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. Solving these problems could lead to major advances in technologies such as quantum computing and spintronics,' said Yen. 'Our findings could open new doors to understanding and controlling the phases and phase transitions of certain materials,' said Tubelik.