Global research team discovers magnetic order in quasicrystals

ANSTO has contributed to international research on quasicrystals that opens the door to tailored magnetic materials.

A team led by Prof Ryuji Tamura at Tokyo University of Science, Prof Taku Sato at Tohoku University in Japan and Prof Max Avdeev at ANSTO and University of Sydney have provided evidence of long-range magnetic order in materials known as quasicrystals for the first time in a study published yesterday in The Journal of the American Chemical Society.

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Researchers had always assumed that every crystalline arrangement of atoms must have a pattern that repeats perfectly in all directions. But the 2011 Nobel Prize in Chemistry recognised the discovery of a whole new category of crystals, which are now known as quasicrystals, whose patterns do not repeat in the traditional way by Dan Shechtman of the Technion–Israel Institute of Technology.

Professor Tamura, Ms Asuka Ishikawa, Dr Shintaro Suzuki of Tokyo University of Science and their associates have been working to determine the physical properties of quasicrystals with icosahedral symmetrythat relate to their unusual structure.

Atomic structure of the Tsai-type icosahedral quasicrystal. Image from The Journal of the American Chemical Society.  Attribution 4.0 International (CC BY 4.0)

“This successful synthesis of ferromagnetic icosahedral quasicrystals is the culmination of more than 10 years of research in our laboratory,” said Prof Tamura.

“Nobody knows what kind of peculiar behaviour magnetic quasicrystals exhibit or how they can be exploited for the advancement of technology, but now we finally have the first step. Elucidating the properties of these magnetic quasicrystals will contribute greatly to the development of science,” Prof Tamura added.

Neutron scattering measurements, undertaken by Prof Avdeev and Dr Chin-Wei Wang on the Echidna instrument at ANSTO’s Australian Centre for Neutron Scattering and by Profs Sato, Okuyama and Nawa on the ISSP-GPTAS instrument at the JRR-3M research reactor in Japan,  confirmed that ferromagnetic ordering, in which the magnetic spins of the atoms were aligned, occurred in two synthesised alloy materials.

A ferromagnetic phase forms in the alloy made of gold (Au), gallium (Ga) and gadolinium (Gd) below 23 K and in an alloy made of gold, gallium, and terbium (Tb) below 16 K.

"Neutron diffraction is a very direct way to identify long-range magnetic order and I am pleased that the experiments on the Echidna diffractometer were successful and confirmed very exciting results. It is fascinating class of materials and we look forward to further studies of magnetically ordered quasicrystals," said Prof Avdeev, Neutron Diffraction Group Manager.

DOI: https://doi.org/10.1021/jacs.1c09954 

Read more on the Tokyo University of Science website