Quasicrystal (QC) possesses a unique lattice structure with rotational symmetry forbidden in conventional crystals. The electric property is far from complete understanding and it has been a long-standing issue whether the magnetic long-range order is realized in the QC. The main difficulty was lack of microscopic theory to analyze the effect of the crystalline electric field (CEF) at the rare-earth atom in QCs. Here we show the full microscopic analysis of the CEF in Tb-based QCs. We find that magnetic anisotropy arising from the CEF plays a key role in realizing unique magnetic textures on the icosahedron whose vertices Tb atoms are located at. Our analysis suggests that the long-range order of the hedgehog characterized by the topological charge of one is stabilized in the Tb-based QC. We also find that the whirling-moment state is characterized by unusually large topological charge of three. The magnetic textures as well as the topological states are shown to be switched by controlling compositions of the non-rare-earth elements in the ternary compounds. Our model is useful to understand the magnetism as well as the topological property in the rare-earth-based QCs and approximant crystals.
Ground-State Phase Diagram of the Effective Model with Antiferromagnetic Nearest-Neighbor and Ferromagnetic Next-Nearest-Neighbor Interactions in 1/1 Periodic Approximants to Icosahedral Quasicrystals
Recent discovery of various magnetism in Tsai-type quasicrystalline approximants, in whose alloys rare-earth ions located on icosahedral apices are coupled with each other via the Ruderman--Kittel--Kasuya--Yosida interaction, opens an avenue to find novel magnetism originating from the icosahedral symmetry. Here we investigate classical and quantum magnetic states on an icosahedral cluster within the Heisenberg interactions of all bonds. Simulated annealing and numerical diagonalization are performed to obtain the classical and quantum ground states. We obtain qualitative correspondence of cla…
Neutron scattering experiments have been performed to elucidate magnetic properties of the quasicrystal approximant Au$_{70}$Si$_{17}$Tb$_{13}$, consisting of icosahedral spin clusters in a body-centered-cubic lattice. Bulk magnetic measurements performed on the single crystalline sample unambiguously confirm long-range ordering at $T_{\rm C} = 11.6 \pm 1$ K. In contrast to the simple ferromagnetic response in the bulk measurements, single crystal neutron diffraction confirms a formation of intriguing non-collinear and non-coplanar magnetic order. The magnetic moment direction was found to be …
Odd-Parity Crystalline Electric Field and Multipoles in Icosahedral Quasicrystal and Approximant: Magnetic Toroidal and Electric Dipoles in Ce-Based Systems
Kyushu Institute of Technology（九州工业大学）；Yokohama National University（横滨国立大学）
Magnetic ground state of a prototype quasicrystal approximant: a candidate for octahedral spin ice physics
ISIS Facility, Rutherford Appleton Laboratory（拉瑟福德·阿普尔顿实验室 ISIS 设施）；Clarendon Laboratory, University of Oxford（牛津大学克拉伦登实验室）；Research Institute for Science and Technology, Tokyo University of Science（东京理科大学理工学研究院）；Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut（保罗谢勒研究所μ自旋谱学实验室）；Department of Materials Science and Technology, Tokyo University of Science（东京理科大学材料科学与技术系）
Entropic crystallization of geometrically frustrated magnets on 1/1 approximant Tsai-type quasicrystal
ENS de Lyon, CNRS, Laboratoire de Physique（巴黎高等师范学院里昂分校，法国国家科学研究中心，物理实验室）；Department of Physics, Gakushuin University（学习院大学物理系）；CNRS, Université de Bordeaux, LOMA, UMR 5798（法国国家科学研究中心，波尔多大学，LOMA实验室）
The quasicrystal(QC)s have unique lattice structure with the rotational symmetry forbidden in the periodic crystals. The electric properties are far from complete understanding. It has been unresolved whether the magnetic long-range orders are realized in the QC. Here we report our theoretical discovery of the ferromagnetic long-range order in the Tb-based QC. The difficulty in past theoretical studies on the QC was lack of the microscopic theory of the crystalline electric field (CEF), which is crucially important in the rare-earth systems. By analyzing the CEF in the Tb-based QC, we clarify …
