Flat Band Generation Through Interlayer Geometric Frustration in Intercalated Transition Metal Dichalcogenides

Abstract Electronic flat bands can lead to rich many‐body quantum phases by quenching the electron's kinetic energy and enhancing many‐body correlation. The reduced bandwidth can be realized by either destructive quantum interference in frustrated lattices, or by generating heavy band folding with avoided band crossing in Moiré superlattices. Here a general approach is proposed to introduce flat bands into widely studied transition metal dichalcogenide (TMD) materials by dilute intercalation. A flat band with vanishing dispersion is observed by angle‐resolved photoemission spectroscopy (ARPES) over the entire momentum space in intercalated Mn _1/4 TaS ₂ . Polarization‐dependent ARPES measurements combined with symmetry analysis reveal the orbital characters of the flat band. Supercell tight‐binding simulations suggest that such flat bands arising from destructive interference between Mn and Ta on S through hopping pathways, are ubiquitous in a range of TMD families as well as for different intercalation configurations. The findings establish a new material platform to manipulate flat band structures and explore their corresponding emergent correlated properties.