Designing Materials that Fully Magnetize Abruptly on Cooling

Designing Materials that Fully Magnetize Abruptly on Cooling - Featured

Theoretical research carried out by the IFIMAC team comprising Petros Andreas Pantazopoulos, Johannes Feist, Francisco J. García-Vidal, and Akashdeep Kamra has resulted in the article “Unconventional magnetism mediated by spin-phonon-photon coupling” published in Nature Communications. It predicts a new class of magnets.

Magnetic order typically emerges due to the short-range exchange interaction between the constituent electronic spins. These conventional magnets manifest zero magnetization above a critical temperature. They slowly and continuously develop a large magnetization on cooling, a behavior characteristic of a second-order phase transition.

In the recently published article, the IFIMAC team theoretically demonstrated the emergence of a biquadratic long-range interaction between spins mediated by their coupling to phonons hybridized with vacuum photons into polaritons. The resulting ordered state enabled by the exchange of virtual polaritons between spins is reminiscent of superconductivity mediated by the exchange of virtual phonons. The biquadratic nature of the spin-spin interaction makes the emergence of magnetic order a first-order phase transition. Consequently, a large magnetization develops abruptly on cooling the material. This feature could enable magnetic memories admitting low-power thermally-assisted writing while maintaining a high data stability. The role of photons in the phenomenon further enables an in-situ static control over the magnetic state. These unique features make the predicted spin-spin interaction and magnetism highly unconventional paving the way for new scientific and technological opportunities. [Full article]

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