2026-10-15 東京大学
本研究の実験配置（上）と観測された電場誘起X線非相反線二色性の要因となる
電場で誘起されるイオン変位（下）。変位の大きさは誇張して描いている。
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2026-10-15-001
- https://journals.aps.org/prx/abstract/10.1103/p5ry-x2wr
ヘマタイトにおける電場誘起X線非相反二色性 Electric-Field-Induced X-Ray Nonreciprocal Dichroism in Hematite
Takeshi Hayashida, Koei Matsumoto, Keito Arakawa, Yves Joly, Sergio Di Matteo, Kenji Tamasaku, Yoshikazu Tanaka, and Tsuyoshi Kimura
Physical Review X Published: 14 October, 2026
DOI: https://doi.org/10.1103/p5ry-x2wr
Abstract
Hematite (α−Fe2O3) is a prototypical room-temperature antiferromagnet whose time-reversal-odd magnetic structure has recently attracted renewed attention. While such magnetic symmetry can be characterized in terms of higher-order multipoles beyond the magnetic dipole, their manifestation in measurable physical phenomena has remained largely elusive. In this work, we investigate x-ray absorption near the Fe -edge of hematite under an applied electric field, which explicitly breaks space-inversion symmetry. We observe an electric-field-induced x-ray nonreciprocal linear dichroism that reflects the time-reversal-odd nature of the magnetic order. A symmetry-resolved multipole analysis attributes this response to the electric-field-induced magnetic quadrupole and the magnetic toroidal octupole induced by the applied electric field. Furthermore, numerical simulations based on ab initio density functional theory reproduce the observed spectra, including their dependence on the antiferromagnetic domain and x-ray polarization. These results indicate that electric-field-modulated x-ray absorption measurements, combined with simulations, provide a framework for identifying the higher-order multipoles contributing to measurable physical responses in time-reversal-odd antiferromagnets, thereby facilitating the investigation of hidden symmetry properties in magnetic materials.
