Two-dimensional electrons at mirror and twistronic twin boundaries in van der Waals ferroelectrics.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39122695.
- Also identified by DOI 10.1038/s41467-024-51176-1 and PMC identifier 11316064.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Semiconducting transition metal dichalcogenides (MX<sub>2</sub>) occur in 2H and rhombohedral (3R) polytypes, respectively distinguished by anti-parallel and parallel orientation of consecutive monolayer lattices. In its bulk form, 3R-MX<sub>2</sub> is ferroelectric, hosting an out-of-plane electric polarisation, the direction of which is dictated by stacking. Here, we predict that twin boundaries, separating adjacent polarisation domains with reversed built-in electric fields, are able to host two-dimensional electrons and holes with an areal density reaching ~ 10<sup>13</sup>cm<sup>-2</sup>. Our modelling suggests that n-doped twin boundaries have a more promising binding energy than p-doped ones, whereas hole accumulation is stable at external surfaces of a twinned film. We also propose that assembling pairs of mono-twin films with a 'magic' twist angle θ<sup>*</sup> that provides commensurability between the moiré pattern at the interface and the accumulated carrier density, should promote a regime of strongly correlated states of electrons, such as Wigner crystals, and we specify the values of θ<sup>*</sup> for homo- and heterostructures of various TMDs.