Flat Moire Bands in Twisted Bilayer WSe₂

The recent observation of correlated phases in transition metal dichalcogenide moire 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 moire superlattice effects in 57.4 degrees twisted WSe2 (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 moire 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 WSe2.