Browsing by Author "Fujii, T"

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    Experimental observation of long-range magnetic order in icosahedral quasicrystals
    (American Chemical Society, 2021-11-17) Tamura, R; Ishikawa, A; Suzuki, S; Kotajima, T; Tanaka, Y; Seki, T; Shibata, N; Yamada, T; Fujii, T; Wang, CW; Avdeev, M; Nawa, K; Okuyama, D; Sato, TJ
    Quasicrystals (QCs), first discovered in 1984, generally do not exhibit long-range magnetic order. Here, we report on long-range magnetic order in the real icosahedral quasicrystals (i QCs) Au–Ga–Gd and Au–Ga–Tb. The Au65Ga20Gd15i QC exhibits a ferromagnetic transition at TC = 23 K, manifested as a sharp anomaly in both magnetic susceptibility and specific heat measurements, along with an appearance of magnetic Bragg peak below TC. This is the first observation of long-range magnetic order in a real quasicrystal, in contrast to the spin-glass-like behaviors observed for the other magnetic quasicrystals found to date. Moreover, when Gd is replaced by Tb, i.e., for the Au65Ga20Tb15i QC, a ferromagnetic behavior is still retained with TC = 16 K. Although the sharp anomaly in the specific heat observed for the Au65Ga20Gd15i QC becomes broadened upon Tb substitution, neutron diffraction experiments clearly show marked development of magnetic Bragg peaks just below TC, indicating long-range magnetic order for the Au65Ga20Tb15i QC also. Our findings can contribute to the further investigation of exotic magnetic orders formed on real quasiperiodic lattices with unprecedented highest global symmetry, i.e., icosahedral symmetry. © 2021 The Authors - CC BY. Published by American Chemical Society
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    Long-range magnetic order in real icosahedral quasicrystals
    (Research Square, 2021-03-22) Tamura, R; Ishikawa, A; Suzuki, S; Kotajima, A; Tanaka, Y; Seki, T; Shibata, N; Yamada, T; Fujii, T; Wang, CW; Avdeev, M; Sato, T
    Quasicrystals (QCs), first discovered in 1984, generally do not exhibit long-range magnetic order. Here, we report on long-range magnetic order in the real icosahedral quasicrystals (i QCs) Au–Ga–Gd and Au–Ga–Tb. The Au65Ga20Gd15 i QC exhibits a ferromagnetic transition at TC = 23 K, manifested as a sharp anomaly in both magnetic-susceptibility and specific-heat measurements. Quick magnetic saturation to almost the full moment (7μB/Gd3+) is observed under 100 Oe at 2 K. This is the first observation of long-range magnetic order in a real quasicrystal, in contrast to the spin-glass-like behaviours observed for the other magnetic quasicrystals found to date. Moreover, when Gd is replaced by Tb, i.e. for the Au65Ga20Tb15 i QC, a ferromagnetic behaviour is still retained with TC = 16 K. Although the sharp anomaly in the specific heat observed for the Au65Ga20Gd15 i QC is significantly broadened upon Tb substitution, neutron-diffraction experiments clearly show the marked development of magnetic Bragg peaks below TC, indicating long-range magnetic order for the Au65Ga20Tb15 i QC also. Our findings can contribute to the further investigation of exotic magnetic orders formed on real quasiperiodic lattices with unprecedented highest global symmetry, i.e. icosahedral symmetry. © This work is licensed under a CC BY 4.0 License.