Imaging gate-induced molecular melting on a graphene field-effect transistor

Franklin Liou; Hsin-Zon Tsai; Zachary A. H. Goodwin; Andrew S. Aikawa; Ethan Ha; Michael Hu; Yiming Yang; Kenji Watanabe; Takashi Taniguchi; Alex Zettl; Johannes Lischner; Michael F. Crommie

arXiv · 2211.13198

Imaging gate-induced molecular melting on a graphene field-effect transistor

Franklin Liou·Hsin-Zon Tsai·Zachary A. H. Goodwin·Andrew S. Aikawa·Ethan Ha·Michael Hu·Yiming Yang·Kenji Watanabe·Takashi Taniguchi·Alex Zettl·Johannes Lischner·Michael F. Crommie

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Abstract

Solid-liquid phase transitions are fundamental physical processes, but atomically-resolved microscopy has yet to capture both the solid and liquid dynamics for such a transition. We have developed a new technique for controlling the melting and freezing of 2D molecular layers on a graphene field-effect transistor (FET) that allows us to image phase transition dynamics via atomically-resolved scanning tunneling microscopy. Back-gate voltages applied to a F4TCNQ-decorated graphene FET induce reversible transitions between a charge-neutral solid phase and a negatively charged liquid phase. Nonequilibrium molecular melting dynamics are visualized by rapidly heating the graphene surface with electrical current and imaging the resulting evolution toward new equilibrium states. An analytical model has been developed that explains the observed equilibrium mixed-state phases based on spectroscopic measurement of both solid and liquid molecular energy levels. Observed non-equilibrium melting dynamics are consistent with Monte Carlo simulations.

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Franklin Liou, Hsin-Zon Tsai, Zachary A. H. Goodwin, Andrew S. Aikawa, Ethan Ha, Michael Hu, Yiming Yang, Kenji Watanabe, Takashi Taniguchi, Alex Zettl, Johannes Lischner, Michael F. Crommie. 2022-11-23. Imaging gate-induced molecular melting on a graphene field-effect transistor. https://arxiv.org/abs/2211.13198

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