2023-04-17 ライス大学
今回、ライス大学の物理学者とその共同研究者は、「スピンエキシトン」と呼ばれる劇的に異なる励起を発見し、ニッケルベースの磁石の中でコヒーレントな波として「波及」させることができることを明らかにした。
＜関連情報＞
- https://news.rice.edu/news/2023/physicists-find-unusual-waves-nickel-based-magnet
- https://www.nature.com/articles/s41467-023-37669-5
単一基底状態系におけるフラストレーションのある三角格子からの拡散性励起子バンド Diffusive excitonic bands from frustrated triangular sublattice in a singlet-ground-state system
Bin Gao,Tong Chen,Xiao-Chuan Wu,Michael Flynn,Chunruo Duan,Lebing Chen,Chien-Lung Huang,Jesse Liebman,Shuyi Li,Feng Ye,Matthew B. Stone,Andrey Podlesnyak,Douglas L. Abernathy,Devashibhai T. Adroja,Manh Duc Le,Qingzhen Huang,Andriy H. Nevidomskyy,Emilia Morosan,Leon Balents & Pengcheng Dai
Nature Communications Published:12 April 2023
DOI:https://doi.org/10.1038/s41467-023-37669-5
Abstract
Magnetic order in most materials occurs when magnetic ions with finite moments arrange in a particular pattern below the ordering temperature. Intriguingly, if the crystal electric field (CEF) effect results in a spin-singlet ground state, a magnetic order can still occur due to the exchange interactions between neighboring ions admixing the excited CEF levels. The magnetic excitations in such a state are spin excitons generally dispersionless in reciprocal space. Here we use neutron scattering to study stoichiometric Ni2Mo3O8, where Ni2+ ions form a bipartite honeycomb lattice comprised of two triangular lattices, with ions subject to the tetrahedral and octahedral crystalline environment, respectively. We find that in both types of ions, the CEF excitations have nonmagnetic singlet ground states, yet the material has magnetic order. Furthermore, CEF spin excitons from the tetrahedral sites form a dispersive diffusive pattern around the Brillouin zone boundary, likely due to spin entanglement and geometric frustrations.
