2023-11-16 オークリッジ国立研究所(ORNL)
◆KYbSe2は三角格子構造を持ち、高品質な超伝導体や量子コンピュータコンポーネントの構築に寄与する可能性があります。研究はNature Physicsに掲載され、QSCメンバーのAllen Scheie氏がリードオーサーを務めました。KYbSe2のスピンダイナミクスを調査し、量子スピン液体状態に近いことを示す証拠を見つけ、真のQSLの迅速な探索に寄与する画期的なプロトコルを確立しました。
＜関連情報＞
- https://www.ornl.gov/news/three-pronged-approach-discerns-qualities-quantum-spin-liquids
- https://www.nature.com/articles/s41567-023-02259-1
三角反強磁性体KYbSe2における近似スピン液体と分数化 Proximate spin liquid and fractionalization in the triangular antiferromagnet KYbSe2
A. O. Scheie,E. A. Ghioldi,J. Xing,J. A. M. Paddison,N. E. Sherman,M. Dupont,L. D. Sanjeewa,Sangyun Lee,A. J. Woods,D. Abernathy,D. M. Pajerowski,T. J. Williams,Shang-Shun Zhang,L. O. Manuel,A. E. Trumper,C. D. Pemmaraju,A. S. Sefat,D. S. Parker,T. P. Devereaux,R. Movshovich,J. E. Moore,C. D. Batista & D. A. Tennant
Nature Physics Published:06 November 2023
DOI:https://doi.org/10.1038/s41567-023-02259-1
Abstract
The Heisenberg triangular-lattice quantum spin liquid and its phase transitions to nearby magnetic orders have received much theoretical attention, but clear experimental manifestations of these states are rare. Here we demonstrate that a spin-half delafossite material, namely, KYbSe2, shows close proximity to the triangular-lattice Heisenberg quantum spin liquid. Using neutron scattering, we identify a diffuse continuum with a sharp lower bound within the measured spectra. Applying entanglement witnesses to the data indicates multipartite entanglement spread between its neighbours, and an analysis of its magnetic-exchange couplings reveals close proximity to the theoretical quantum spin-liquid phase. The key features of the data are reproduced by Schwinger boson theory and tensor network calculations with a substantial next-nearest-neighbour coupling. The strength of the dynamical structure factor at the Brillouin-zone K point shows a scaling collapse down to 0.3 K, indicating the existence of a second-order quantum phase transition. Comparing this with previous theoretical work suggests that the proximate phase at a larger next-nearest-neighbour coupling is a gapped Z2 spin liquid, resolving a long-debated issue.
