Quasicrystals are very interesting entities. They have ordered structures but they do not repeat, so they are – as the name suggests – almost like
This is the first time that the magnetic properties of this particular quasicrystal have been explored, and the research shows that they are quite unique. The team believes that the breakthrough is pushing the field of condensed matter physics and
The quasicrystal in question is made of gold, gallium, and terbium. One of the structures is an icosahedron – a 3D figure with 20 faces – as well as an approximant crystal (AC) that is cubic. Both of them are Tsai-types. These kinds of quasicrystals and approximants are made of four concentric shells with a tetrahedron at the very center. A tetrahedron is a pyramid shape in which all four faces are triangles.
Next up is the magnetism part. These quasicrystals don’t follow the classical Heisenberg model of
This might already seem quite complex, but we are just getting started. In the immortal words of Samuel L. Jackson in
Depending on the number of available electrons per atom (the e/a ratio), the magnetic properties of these quasicrystals are wild. Above a ratio of 1.9, the crystal is a so-called spin glass, so all the magnetic moments of the atoms are randomly interacting.
Below that, things get interesting. Around a ratio of 1.8, the material has strong whirling ferromagnetism – the magnetic moments all align, and the crystal is magnetized and remains so.
But if the ratio falls below 1.7, a third thing happens. The structure becomes a whirling antiferromagnet. Its magnetic moments all cancel out, delivering zero total magnetism.
The oddities all happen at just a handful of degrees above absolute zero. It shows that magnetic behavior is far from simple for both the icosahedral quasicrystals (iQCs) and their AC counterparts.
“These results offer important insights into the intricate interplay between magnetic interactions in non-Heisenberg Tsai-type ACs. They lay the foundation for understanding the intriguing properties of not only non-Heisenberg ACs but also non-Heisenberg iQCs that are yet to be discovered,” senior author Professor Ryuji Tamura, from Tokyo University of Science, said in a
Quasicrystals such as this are considered potential units for memory storage in future
The study is is published in the journal