We determine strain-temperature phase diagrams that map the stability of ferroelectric ordering and domains in nanothin (1.6-20 nm) films of PbTiO 3 using molecular dynamics based on a first-principles model Hamiltonian. The ferroelectric domain structure is shown to depend sensitively on the epitaxial strain and the nature of the electrodes that screen the surface charges of a ferroelectric. We show that a broad peak in the dielectric response as a function of temperature marks a diffuse transition to a flux closure stripe-domain structure in the ultrathin films with incomplete screening of charges at their interface with the electrode. We demonstrate that the strain-phonon coupling is fundamental to the stability and topology of such a domain structure, which can be engineered at the nanoscale with a suitable choice of electrodes and substrate, and used in ultrahigh-density memory chips.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2013 Aug 21|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics