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arXiv · 2211.01192

Observation of flat $\Gamma$ moir\'e bands in twisted bilayer WSe$_2$

Gianmarco Gatti·Julia Issing·Louk Rademaker·Florian Margot·Tobias A. de Jong·Sense Jan van der Molen·Jérémie Teyssier·Timur K. Kim·Matthew D. Watson·Cephise Cacho·Pavel Dudin·José Avila·Kumara Cordero Edwards·Patrycja Paruch·Nicolas Ubrig·Ignacio Gutiérrez-Lezama·Alberto Morpurgo·Anna Tamai·Felix Baumberger
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Abstract

The recent observation of correlated phases in transition metal dichalcogenide moir\'e systems at integer and fractional filling promises new insight into metal-insulator transitions and the unusual states of matter that can emerge near such transitions. Here, we combine real- and momentum-space mapping techniques to study moir\'e superlattice effects in 57.4$^{\circ}$ twisted WSe$_2$ (tWSe$_2$). Our data reveal a split-off flat band that derives from the monolayer $\Gamma$ states. Using advanced data analysis, we directly quantify the moir\'e potential from our data. We further demonstrate that the global valence band maximum in tWSe$_2$ is close in energy to this flat band but derives from the monolayer K-states which show weaker superlattice effects. These results constrain theoretical models and open the perspective that $\Gamma$-valley flat bands might be involved in the correlated physics of twisted WSe$_2$.

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Gianmarco Gatti, Julia Issing, Louk Rademaker, Florian Margot, Tobias A. de Jong, Sense Jan van der Molen, Jérémie Teyssier, Timur K. Kim, Matthew D. Watson, Cephise Cacho, Pavel Dudin, José Avila, Kumara Cordero Edwards, Patrycja Paruch, Nicolas Ubrig, Ignacio Gutiérrez-Lezama, Alberto Morpurgo, Anna Tamai, Felix Baumberger. 2022-11-02. Observation of flat $\Gamma$ moir\'e bands in twisted bilayer WSe$_2$. https://doi.org/10.1103/physrevlett.131.046401

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