Novel electronic structures from anomalous stackings in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>NbS</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:

We show that in some transition metal dichalcogenides, minority regions of the cleaved sample surfaces show—unexpectedly and anomalously—a finite number of 2D electronic states instead of the expected 3D valence bands. In the case of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>NbS</a:mi><a:mn>2</a:mn></a:msub></a:math>, in addition to the typical spectrum associated with bulk 2Ha stacking, we also find minority regions with electronic structures consistent with few layers of 3R stacking. In <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>MoS</b:mi><b:mn>2</b:mn></b:msub></b:math>, we find areas of both bulk 2Hc and 3R stackings, and regions exhibiting finite-layer quantization of both types. We further find evidence for a more exotic 4Ha stacking of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>MoS</c:mi><c:mn>2</c:mn></c:msub></c:math>, in which the valence band maximum is quasi-2D. The results highlight how variation of the interlayer stacking of van der Waals materials beyond the commonly reported bulk polytypes can yield novel electronic structures. Published by the American Physical Society 2024