2026-06-23 東京理科大学
図1 (a) YbB12の結晶構造と相図 (b) フェルミ粒子-音響フォノン相互作用のイメージ図。超音波（音響フォノン）は、フェルミ面近傍の粒子と相互作用する。これにより、量子振動を示す粒子の存在の有無を調べることができる。
＜関連情報＞
- https://www.tus.ac.jp/today/archive/20260615_1865.html
- https://journals.aps.org/prb/abstract/10.1103/m3gy-g9tv
絶縁相における磁気音響量子振動の探索YbB12 Search for magnetoacoustic quantum oscillations in the insulating phase of YbB12
Ryosuke Kurihara, Atsuhiko Miyata, Koji Araki, Shusaku Imajo, Ruo Hibino, Atsushi Miyake, Sergei Zherlitsyn, Joachim Wosnitza,, Hiroshi Yaguchi et al.
Physical Review B Published: 16 June, 2026
DOI: https://doi.org/10.1103/m3gy-g9tv
Abstract
A highly exotic phenomenon in solid-state physics is the observation of magnetic quantum oscillations in insulators. For instance, in the Kondo insulator YbB12 various groups reported the observation of such oscillations seemingly originating from Fermi surfaces, though this contradicts the concept of an insulator having no charged quasiparticles. In this study, we searched for quantum oscillations in YbB12 by using bulk-sensitive ultrasonic experiments in high magnetic fields up to 65 T and down to 485 mK. For that, we utilized an YbB12 single crystal that, in previous experiments, revealed oscillations in the magnetoresistance in the insulating state. We confirmed oscillationlike behavior of the magnetoresistance as well as field-dependent oscillations in the magnetocaloric effect. However, we could not observe magnetoacoustic quantum oscillations in the insulating state, only in the field-induced metallic state. In the insulating state, we found some anomalies in our ultrasound data, the origin of which remains elusive. Our findings provide further information on the puzzling behavior of the insulating state of YbB12.
