Phonon-limited valley life times in single-particle bilayer graphene quantum dots

• URL: http://arxiv.org/abs/2402.16691v2
• Date: Wed, 22 Jan 2025 15:13:25 GMT
• Title: Phonon-limited valley life times in single-particle bilayer graphene quantum dots
• Authors: Luca Banszerus, Katrin Hecker, Lin Wang, Samuel Möller, Kenji Watanabe, Takashi Taniguchi, Guido Burkard, Christian Volk, Christoph Stampfer,
• Abstract summary: We report single-particle valley relaxation times exceeding several microseconds in electrostatically defined BLG quantum dots (QDs) using a pulse-gating technique. We identify the coupling to acoustic phonons via the bond length change and via the deformation potential as the limiting mechanisms.
• Score: 3.690319578578481
• License:
• Abstract: The valley degree of freedom in 2D semiconductors, such as gapped bilayer graphene (BLG) and transition metal dichalcogenides, is a promising carrier of quantum information in the emerging field of valleytronics. While valley dynamics have been extensively studied for moderate band gap 2D~semiconductors using optical spectroscopy techniques, very little is known about valley lifetimes in narrow band gap BLG, which is difficult to study using optical techniques. Here, we report single-particle valley relaxation times ($T_1$) exceeding several microseconds in electrostatically defined BLG quantum dots (QDs) using a pulse-gating technique. The observed dependence of $T_1$ on perpendicular magnetic field can be understood qualitatively and quantitatively by a model in which $T_1$ is limited by electron-phonon coupling. We identify the coupling to acoustic phonons via the bond length change and via the deformation potential as the limiting mechanisms.

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