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arXiv · 2402.16691

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

Luca Banszerus·Katrin Hecker·Lin Wang·Samuel Möller·Kenji Watanabe·Takashi Taniguchi·Guido Burkard·Christian Volk·Christoph Stampfer
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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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Luca Banszerus, Katrin Hecker, Lin Wang, Samuel Möller, Kenji Watanabe, Takashi Taniguchi, Guido Burkard, Christian Volk, Christoph Stampfer. 2024-02-26. Phonon-limited valley life times in single-particle bilayer graphene quantum dots. https://doi.org/10.1103/dkgn-pfjb

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