2023-05-11 ブラウン大学
◆しかし、Brown大学の研究者らによる研究では、2D材料中の電子スピンとマイクロ波放射からの光子との直接相互作用を示す初めての測定が行われた。これにより、これらの材料に基づく計算・通信技術の開発の基盤となる、直接的にスピンの特性を研究する新しい実験的手法が確立されたと研究者らは述べている。
＜関連情報＞
- https://www.brown.edu/news/2023-05-11/2d-electronics
- https://www.nature.com/articles/s41567-023-02060-0
ねじれた二層グラフェンにおいてディラックの再生による共振反応 Dirac revivals drive a resonance response in twisted bilayer graphene
Erin Morissette,Jiang-Xiazi Lin,Dihao Sun,Liangji Zhang,Song Liu,Daniel Rhodes,Kenji Watanabe,Takashi Taniguchi,James Hone,Johannes Pollanen,Mathias S. Scheurer,Michael Lilly,Andrew Mounce & J. I. A. Li
Nature Physics Published:11 May 2023
DOI:https://doi.org/10.1038/s41567-023-02060-0
Abstract
Collective excitations contain key information regarding the electronic order of the ground state of strongly correlated systems. Various collective modes in the spin and valley isospin channels of magic-angle graphene moiré bands have been alluded to by a series of recent experiments. However, a direct observation of collective excitations has been impossible due to the lack of a spin probe. Here we observe low-energy collective excitations in twisted bilayer graphene near the magic angle, using a resistively detected electron spin resonance technique. Two independent observations show that the generation and detection of microwave resonance relies on the strong correlations within the flat moiré energy band. First, the onset of the resonance response coincides with the spontaneous flavour polarization at moiré half-filling, but is absent in the isospin unpolarized density range. Second, we perform the same measurement on various systems that do not have flat bands and observe no indication of a resonance response in these samples. Our explanation is that the resonance response near the magic angle originates from Dirac revivals and the resulting isospin order.
