Topological magnon bands in kagome antiferromagnets

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14395
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Tohoku University
• Principal Investigator: Nawa Kazuhiro 東北大学, 多元物質科学研究所, 助教 (10723215)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: カゴメ格子反強磁性体 / トポロジー / マグノン

Outline of Final Research Achievements

Recently, electronic properties of solids have been understood in terms of topology, which represents how wavefunctions are connected in reciprocal lattice space. The concept of topology is not only discussed for electrons but also extended to bosonic particles, such as magnons. We have investigated the magnon band topology in the Kagome lattice antiferromagnet jarosite. Single crystalline samples were grown by hydrothermal synthesis, and used for inelastic neutron scattering experiments. Dispersions of three magnon modes from the Γ point to the M point were observed. In addition, inelastic neutron scattering spectra suggest a strong direction dependence around the Γ point and the opposite intensity distribution between the magnon bands. These results are consistent with the nontrivial topology of the magnon bands around the Γ point.

Free Research Field

磁性

Academic Significance and Societal Importance of the Research Achievements

非共線磁気構造を持つ反強磁性体に関して非偏極中性子非弾性散乱実験からマグノンのねじれたトポロジーを帯びている兆候をとらえることができた例は研究代表者が知る限り本研究が初めてである。ねじれたトポロジーを生ずる原因は磁性体における副格子自由度とジャロシンスキー守谷相互作用である、電子系におけるスピンと異なる副格子自由度は磁性体を選ぶことで自由に増やしたり減らしたりすることができる。本研究をきっかけに、ねじれたトポロジーを有するマグノン物性の開発が大きく進展すると期待される。