2024-01-24 スイス連邦工科大学ローザンヌ校(EPFL)
◆特に、ストロンチウム銅ホウ酸塩において磁気波の研究が行われ、予想外の結合状態「スピン・ネマティック相」が発見されました。この異例の挙動は、量子物理学の新たな規則を示し、未知の量子技術への可能性を示唆しています。
＜関連情報＞
- https://actu.epfl.ch/news/a-new-state-in-a-quantum-material/
- https://www.nature.com/articles/s41467-023-44115-z
SrCu2(BO3)2における磁場誘起束縛状態凝縮とスピンネマチック相が25.9Tまでの中性子散乱によって明らかになった Field-induced bound-state condensation and spin-nematic phase in SrCu2(BO3)2 revealed by neutron scattering up to 25.9 T
Ellen Fogh,Mithilesh Nayak,Oleksandr Prokhnenko,Maciej Bartkowiak,Koji Munakata,Jian-Rui Soh,Alexandra A. Turrini,Mohamed E. Zayed,Ekaterina Pomjakushina,Hiroshi Kageyama,Hiroyuki Nojiri,Kazuhisa Kakurai,Bruce Normand,Frédéric Mila & Henrik M. Rønnow
Nature Communications Published:10 January 2024
DOI:https://doi.org/10.1038/s41467-023-44115-z
Abstract
In quantum magnetic materials, ordered phases induced by an applied magnetic field can be described as the Bose-Einstein condensation (BEC) of magnon excitations. In the strongly frustrated system SrCu2(BO3)2, no clear magnon BEC could be observed, pointing to an alternative mechanism, but the high fields required to probe this physics have remained a barrier to detailed investigation. Here we exploit the first purpose-built high-field neutron scattering facility to measure the spin excitations of SrCu2(BO3)2 up to 25.9 T and use cylinder matrix-product-states (MPS) calculations to reproduce the experimental spectra with high accuracy. Multiple unconventional features point to a condensation of S = 2 bound states into a spin-nematic phase, including the gradients of the one-magnon branches and the persistence of a one-magnon spin gap. This gap reflects a direct analogy with superconductivity, suggesting that the spin-nematic phase in SrCu2(BO3)2 is best understood as a condensate of bosonic Cooper pairs.
