The magnetic phase diagram of non-Heisenberg-type approximant crystals is revealed for the first time by researchers, spurring further applied research.
Magnetic phase diagram of the systems uncovered in this study. A magnetic phase diagram of the Au-Ga-Tb 1/1 ACs showing e/a dependence of TC, TN, or Tf (red markers). The yellow, cyan, and dark blue background colors represent whirling AFM, whirling FM, and spin-glass regimes, respectively. The corresponding magnetic structures of the whirling AFM and FM orders are shown on top. Image Credit: Farid Labib from Tokyo University of Science
Intermetallic materials known as quasicrystals have attracted a lot of interest from scientists, hoping to improve the understanding of condensed matter physics. Quasicrystals have non-repeating ordered patterns of atoms, in contrast to normal crystals, which have atoms arranged in an ordered repeating pattern.
Many exotic and fascinating properties result from their unique structure, and these properties are especially helpful for real-world applications in magnetic refrigeration and spintronics.
The Tsai-type icosahedral quasicrystal (iQC) and its cubic approximant crystals (ACs) are a special kind of quasicrystal that exhibits interesting properties. These include, among others, unconventional quantum critical phenomena and long-range ferromagnetic (FM) and anti-ferromagnetic (AFM) orders.
These materials can also display interesting properties like aging, memory, and rejuvenation through precise compositional modifications, which makes them appropriate for the creation of next-generation magnetic storage devices. However, despite their potential, little is known about these materials' magnetic phase diagrams.
A group of researchers recently performed magnetization and powder neutron diffraction (PND) experiments on the non-Heisenberg Tsai-type 1/1 gold-gallium-terbium AC in order to learn more. The researchers were led by Professor Ryuji Tamura from the Department of Materials Science and Technology at Tokyo University of Science (TUS) and worked in conjunction with researchers from Tohoku University.
For the first time, the phase diagrams of the non-Heisenberg Tsai-type AC have been unraveled. This will boost applied physics research on magnetic refrigeration and spintronics.
Ryuji Tamura, Professor, Department of Materials Science and Technology, Tokyo University of Science
The findings were published in the journal Materials Today Physics on December 19th, 2023.
The scientists conducted multiple experiments to create the first complete magnetic phase diagram of the non-Heisenberg Tsai-type AC, which spans a wide range of electron-per-atom (e/a) ratios—a parameter that is essential to comprehend the basic properties of QCs.
Furthermore, a noncoplanar whirling AFM order at an e/a ratio of 1.72 and a noncoplanar whirling FM order at an e/a ratio of 1.80 were detected by powder neutron diffraction (PND) measurements.
Through the analysis of the relative orientation of magnetic moments between nearest-neighbor and next-nearest-neighbor sites, the team further clarified the ferromagnetic and anti-ferromagnetic phase selection rule of magnetic interactions.
Professor Tamura adds that their findings open up new doors for the future of condensed matter physics.
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.
Ryuji Tamura, Professor, Department of Materials Science and Technology, Tokyo University of Science
In conclusion, this discovery opens up new avenues for the study of quasicrystals and condensed matter physics, opening the door to the development of sophisticated electronics and cutting-edge refrigeration systems!
Journal Reference:
Labib, F., et al. (2023). Unveiling exotic magnetic phase diagram of a non-Heisenberg quasicrystal approximant. Science Direct. doi.org/10.1016/j.mtphys.2023.101321.