Interlayer-coupling-engineerable flat bands in twisted MoSi 2 N 4 bilayers.

The two-dimensional layered semiconductor MoSi 2 N 4 , which has several advantages including high strength, excellent stability, high hole mobility, and high thermal conductivity, was recently successfully synthesized using chemical vapor deposition. Based on first-principles calculations, we investigate the effects of the twist angle and interlayer distance variation on the electronic properties of twisted bilayer MoSi 2 N 4 . The flat bands are absent for twisted bilayer MoSi 2 N 4 when the twist angle θ is reduced to 3.89°. Taking twisted bilayer MoSi 2 N 4 with θ of 5.09° as an example, we find that flat bands emerge as the interlayer distance decreases. As the interlayer distance can be effectively modulated by hydrostatic pressure, we propose hydrostatic pressure as a knob for tailoring the flat bands in twisted bilayer MoSi 2 N 4 . Our findings provide theoretical support for extending the applications of MoSi 2 N 4 in strong correlation physics and superconductivity.