Two-dimensional Frank-van-der-Merwe growth of functional oxide and nitride thin film superlattices by pulsed laser deposition

Pulsed laser deposition is one of the most flexible growth methods for high-quality epitaxial multifunctional thin films and short-period superlattices. The following examples of current research interest demonstrate the state-of-the art: First, it is shown that the magnetoelectric performance of multiferroic BiFeO3-BaTiO3 (001)-oriented superlattices depends on the crystalline coherence of the different layers at the interfaces. Second, it is exemplified that dielectric-plasmonic superlattices built from the electrically insulating oxide MgO and the metallically conducting nitride TiN are promising metamaterials with hyperbolic dispersion. As a third example, it is demonstrated that LaNiO3- and LaMnO3-based superlattices with (001)-, (011)-, and (111)-out-of-plane orientation and controlled single layer thickness from 2 to 15 atomic monolayers show metal-insulator transitions and tunable gaps, in partial agreement with density functional theory calculations. Underlined by these examples, it is shown that the precise control of an epitaxially coherent, or two-dimensional layer-by-layer growth, named after Jan van der Merwe, is a prerequisite to achieve the desired functionality of oxide-oxide and oxide-nitride superlattices.