Atomic scale investigations of ferroelectricity in perovskite thin films

Superlattices of suitable perovskite oxides can be used to create novel materials for device applications. Calculations have shown that superlattices with atomically flat, compositionally abrupt interfaces will result in enhanced ferroelectric properties due to strain, changes in bonding and charge compensation at the interfaces. But can these abrupt interfaces be actually grown and monitored at an atomic level? We have shown that it is possible to produce structures hundreds of layers thick using two and three perovskite building blocks.[1–2] Our CaTiO3/SrTiO3/BaTiO3 superlattices exhibited a 50% enhancement in ferroelectric polarization compared with BaTiO3. These films were grown using pulsed laser deposition (PLD) using stoichiometric perovskite targets. The deposition of each unit cell of the films was monitored using the intensity oscillations of the reflection high-energy electron diffraction specular spot.