'Half ice, half fire': Physicists discover new phase of matter in a magnetic material. A twin state of “half fire, half ice”.

Amazing stuff!

"Two scientists ... have discovered a new phase of matter while studying a model system of a magnetic material.

The phase is a never-before-seen pattern of electron spins — the tiny “up” or “down” magnetic moments carried by every electron. It consists of a combination of highly ordered spins and highly disordered spins. The highly ordered spins are referred to as “cold,” while the highly disordered spins are “hot,” which led the researchers to dub the new phase “half ice, half fire.” They discovered the phase while studying a one-dimensional model of a type of magnetic material called a ferrimagnet. ...

The “half-ice, half-fire” phase is the twin state of the “half-fire, half-ice” phase discovered ... 2015 ... They describe the discovery in a paper published in early 2024. ...

studying Sr3CuIrO6, a magnetic compound of strontium, copper, iridium, and oxygen ..."

From the abstract:

"The notion of “half fire, half ice” was recently introduced to describe an exotic macroscopic ground-state degeneracy emerging in a ferrimagnet under the critical magnetic field, in which the “hot” spins are fully disordered on the sublattice with smaller magnetic moments and the “cold” spins are fully ordered on the sublattice with larger magnetic moments.

Here, we further point out that this state has a twin named “half ice, half fire” in which the hot and cold spins switch positions. The new state is an excited state—thus hidden in the ground-state phase diagram—and is robust with respect to the interactions that destroy the half-fire, half-ice state.

We demonstrate with exact results how this hidden state can drive phase switching at desirable finite temperature, even for the one-dimensional Ising model where phase transition at finite temperature is forbidden. We suggest that our findings may open a new door to the understanding and controlling of phase competition and transition in unconventional frustrated systems."

'Half ice, half fire': Physicists discover new phase of matter in a magnetic material

Brookhaven Physicists Discover New Phase of Matter in a Magnetic Material (original news release) "The "half-ice, half-fire" phase, a twin to the recently discovered "half-fire, half-ice" state, opens a new route of potential physics discovery"

Phase Switch Driven by the Hidden Half-Ice, Half-Fire State in a Ferrimagnet (no public access)

Phase Switch Driven by the Hidden Half-Ice, Half-Fire State in a Ferrimagnet (preprint, open access)

This image shows a graphical interpretation of the "half-ice, half-fire" and "half-fire, half-ice" states (left). The plot (right) shows the magnetic entropy change in the magnetic field (h) versus temperature (T) plane. The black dot at zero temperature indicates where the half-fire, half-ice state appears. The dashed line indicates where the half-ice, half-fire state hides.