Download file (2.45MB)
Download as zip (2.09MB)

コレクション

引用

説明:

The exchange interactions in insulators depend on the orbital state of magnetic ions, obeying certain phenomenological principles, known as Goodenough-Kanamori-Anderson rules. Particularly, the ferro order of alike orbitals tends to stabilize antiferromagnetic interactions, while the antiferro order of unlike orbitals favors ferromagnetic interactions. The Kugel-Khomskii theory provides a universal view on such coupling between spin and orbital degrees of freedom, based on the superexchange processes: namely, for a given magnetic order, the occupied orbitals tend to arrange in a way to further minimize the exchange energy. Then, if two magnetic sites are connected by the spatial inversion, the antiferro orbital order should lead to the ferromagnetic coupling and break the inversion symmetry. This constitutes the basic idea of our work, which opens a new route for designing ferromagnetic ferroelectrics -- the rare but fundamentally and practically important multiferroic materials. After illustrating the basic idea on toy-model examples, we propose that such behavior can be indeed realized in the van der Waals ferromagnet VI3, employing for this analysis the realistic model derived from first-principles calculations for magnetic 3d bands. We argue that the intraatomic Coulomb interactions responsible for Hund's second rule, acting against the crystal field, tend to restore the orbital degeneracy of the ionic d2 state in VI3 and, thus, provide a necessary flexibility for activating the Kugel-Khomskii mechanism of the orbital ordering. In the honeycomb lattice, this orbital ordering breaks the inversion symmetry, stabilizing the ferromagnetic-ferroelectric ground state. The symmetry breaking leads to the canting of magnetization, which can be further controlled by the magnetic field, producing a huge change of electric polarization.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

  Published by the American Physical Society under the terms of the
  Creative Commons Attribution 4.0 International license. Further
  distribution of this work must maintain attribution to the author(s)
  and the published article’s title, journal citation, and DOI.

キーワード: ferroelectricity, ferromagnetism, multiferroic, van der Waals materials, electronic structure calculations, orbital ordering, Hund's rules

刊行年月日: 2024-11-07

出版者: American Physical Society

掲載誌:

• PHYSICAL REVIEW B (ISSN: 24699950) vol. 110 205116

研究助成金:

• JSPS KAKENHI Grant No. JP23KJ2165

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1103/PhysRevB.110.205116

関連資料:

その他の識別子:

連絡先:

更新時刻: 2024-11-08 16:30:28 +0900

MDRでの公開時刻: 2024-11-08 16:30:28 +0900