Graphene quantum dots (QDs) are intensively studied as platforms for the next generation of quantum electronic devices. Fine tuning of the transport properties in monolayer graphene QDs, in particular with respect to the independent modulation of the tunnel barrier transparencies, remains challenging and is typically addressed using electrostatic gating. We investigate charge transport in back-gated graphene mechanical break junctions and reveal Coulomb blockade physics characteristic of a single, high-quality QD when a nanogap is opened in a graphene constriction. By mechanically controlling the distance across the newly-formed graphene nanogap, we achieve reversible tunability of the tunnel coupling to the drain electrode by five orders of magnitude, while keeping the source-QD tunnel coupling constant. These findings indicate that the tunnel coupling asymmetry can be significantly modulated with a mechanical tuning knob and has important implications for the development of future graphene-based devices, including energy converters and quantum calorimeters.
@article{arxiv.2002.03992,
title = {A Mechanically Tunable Quantum Dot in a Graphene Break Junction},
author = {Sabina Caneva and Matthijs D. Hermans and Martin Lee and Amador Garcia-Fuente and Kenji Watanabe and Takashi Taniguchi and Cees Dekker and Jaime Ferrer and Herre S. J. van der Zant and Pascal Gehring},
journal= {arXiv preprint arXiv:2002.03992},
year = {2020}
}