Tunable p–p Interactions Along Linear Chains Control Metavalent Bonding in Chalcogenide Heterostructures

We present an analysis of heterostructures of alternating layers of rocksalt structures of metavalently bonded (MVB) group‐IV ( MX ) and ionic chalcogenides ( IX ) and show that bonding heterogeneity across their semiconductor‐insulator interface arises from the tunable p – p interactions. Using Born dynamical charge () as the key atomistic descriptor of MVB, we demonstrate that metavalent bonds parallel to the interfacial plane are unaffected by proximal ionic bonds as they constitute periodic (‐ X ‐ M ‐) n chains. In contrast, the bonds perpendicular to the interface ( ‐X‐M‐X‐I‐X‐ ) are spectacularly affected: characteristic of the MVB evolve to the bulk behavior within about a nm of the interface. With comparative analysis with I = Sr, Cd, and Sn, we establish that interatomic p – p orbital interactions along linear atomic chains with 5 contiguous (‐ X ‐ M‐ ) pairs govern the emergence, persistence, and suppression of MVB. The discontinuity at the interface has long‐range effects on the out‐of‐plane component of of ions, which are explained using a simple model of electrostatic screening. Energies of p orbitals of anions and cations, and their interactions along (‐ X ‐ M ‐) n chains are shown here to be essential to MVB, which result in the tunability of thermoelectric properties of interfacial hetero‐structures of chalcogenides.