Scaling of structure and electrical properties in ultrathin epitaxial ferroelectric heterostructures
EstadísticasView Usage Statistics
Full recordShow full item record
AuthorNagarajan, Valanoor; Junquera Quintana, Francisco Javier; He, Jiaqing; Jia, Chunlin; Waser, Rainer M.; Lee, KyoungIl; Kim, Youngkeun; Baik, Sunggi; Zhao, Tong; Ramesh, Ramamoorthy; Ghosez, Philippe; Rabe, Karin M.
Scaling of the structural order parameter, polarization, and electrical properties was investigated in model ultrathin epitaxial SrRuO3/PbZr0.2Ti0.8O3/SrRuO3/SrTiO3 heterostructures. High-resolution transmission electron microscopy images revealed the interfaces to be sharp and fully coherent. Synchrotron x-ray studies show that a high tetragonality (c/a∼1.058) is maintained down to 50Å thick films, suggesting indirectly that ferroelectricity is fully preserved at such small thicknesses. However, measurement of the switchable polarization (ΔP) using a pulsed probe setup and the out-of-plane piezoelectric response (d33) revealed a systematic drop from ∼140μC/cm2 and 60pm/V for a 150Å thick film to 11μC/cm2 and 7pm/V for a 50Å thick film. This apparent contradiction between the structural measurements and the measured switchable polarization is explained by an increasing presence of a strong depolarization field, which creates a pinned 180° polydomain state for the thinnest films. Existence of a polydomain state is demonstrated by piezoresponse force microscopy images of the ultrathin films. These results suggest that the limit for a ferroelectric memory device may be much larger than the fundamental limit for ferroelectricity.
Enlace a la publicación
Collections to which it belong
- D29 Artículos