The breakthrough, published in the Journal of the American Chemical Society, rests on a machine-learning-powered hunt through compositional space. Professor Ryuji Tamura and Dr. Farid Labib used a phase classifier trained on the HYPOD-X quasicrystal database to screen 675 quinary alloy systems for candidates that might form stable ferromagnetic quasicrystals. The algorithm zeroed in on gold–copper–aluminum–indium–rare-earth systems, specifically those containing gadolinium, terbium, or dysprosium. Unlike earlier materials that required violent rapid quenching from a melt and fell apart upon heating, these new alloys were synthesized by conventional arc melting and then patiently annealed at 723 Kelvin for days. Rather than collapsing into periodic approximant crystals as older quasicrystals did, the new compounds stayed icosahedrally ordered, their quasiperiodic coherence dramatically improving with time.

Electron diffraction patterns from the annealed samples revealed sharp Bragg-like spots, a hallmark of exceptional quasicrystalline order that had never been reached in a ferromagnetic specimen. Magnetic and specific heat measurements then confirmed what the diffraction only hinted at: bulk, long-range ferromagnetic transitions at cryogenic temperatures ranging from 9.7 Kelvin for the gadolinium variant to 28.3 Kelvin for the dysprosium version. The team had, for the first time, a pristine quasicrystalline lattice in which to study how quasiperiodicity rewrites the rules of magnetic criticality—the collective behaviour of spins near the Curie point.

What they found split the three compounds into two strikingly different universality classes, despite the near-identical icosahedral scaffolds. The terbium- and dysprosium-based quasicrystals exhibited critical exponents that hug the mean-field values, signalling infinitely long-range magnetic interactions that wash out spatial fluctuations. In sharp contrast, the gadolinium compound veered away from mean-field theory towards shorter-range correlations. The team attributes this divergence to single-ion magnetic anisotropy. Terbium and dysprosium carry strong local magnetic anisotropy that pins fluctuations, forcing the system to behave as if every spin talks to all others equally. Gadolinium, an S-state ion with negligible anisotropy, allows spins to swing more freely, enabling genuine critical fluctuations to shrink the effective interaction length.

“These results indicate that magnetic criticality in quasicrystals is determined by the combination of quasiperiodic order and spin symmetry,” Tamura explains. The quasiperiodic geometry alone does not dictate magnetic behaviour; rather, it enters a subtle dialogue with the quantum character of the magnetic ions. The finding that a single structural platform can host both mean-field and non-mean-field criticality simply by swapping the rare-earth element offers a new tuning knob for magnetic materials engineering.

This portability of critical behaviour is not just a theoretical prize. Quasicrystals are known to exhibit ultra-low thermal conductivity, high hardness, and unusual electronic properties. Adding controllable, intrinsic ferromagnetism opens the door to multifunctional materials that could, for instance, convert waste heat into spin currents or serve as magnetocaloric refrigerants. The stable, annealable nature of these specimens means that researchers can now conduct the full suite of precision experiments—neutron scattering, angle-resolved photoemission, and scanning tunnelling microscopy—that had been impossible on the metastable quasicrystals of the past.

The study’s machine-learning methodology is itself a signal of how materials discovery is evolving. By systematically generating and scoring quinary candidate systems, Tamura’s group reduced what would have been an intractable experimental bottleneck to a focused synthesis campaign. The success proves that the third generation of quasicrystal research can be driven by computational prediction, a route that may finally map the long-elusive phase diagrams of these aperiodic solids.

Beyond the immediate findings, the work upgrades ferromagnetic quasicrystals from a fragile novelty to a robust materials class. The same approach could soon yield quasicrystals with antiferromagnetism, helical order, or even quantum spin liquid behaviour. As Tamura notes, understanding how quasiperiodicity influences magnetic fluctuations may ultimately enable the design of materials with bespoke magnetic responses for next-generation sensing, energy-conversion, and information-processing technologies. The fridge magnet has just met its strangest cousin yet.

Subject of Research: Not applicable
Article Title: Bulk Ferromagnetic Icosahedral Quasicrystals without Rapid Quenching
News Publication Date: 7-Jul-2026
Web References: 10.1021/jacs.6c03748; Tamura Laboratory; Tokyo University of Science profile
References: DOI: 10.1021/jacs.6c03748
Image Credits: Professor Ryuji Tamura from TUS, Japan

Keywords

Quasicrystals, ferromagnetism, magnetic criticality, machine learning, icosahedral phase, rare-earth alloys, materials engineering, phase transitions, crystallography, quantum materials