Elastic Relaxation and Correlation of Local Strain Gradients with Ferroelectric Domains in (001) BiFeO3 Nanostructures

Researchers at Argonne National Laboratory (MSD and CNM) have recently performed first worldwide studies of effects of nanopatterning on fundamental phenomena in mutiferroic BiFeO3 (BFO) nanostructures, using the APS-CNM nanoprobe beam (50 nm diameter). Nano-focused x-ray diffraction microscopy provided new insights into the relationship between film strain and ferroelectric domains in nanostructures, namely: i) an out-of-plane strain enhancement of as much as -1.8% Δc/c in a BFO film-based nanostructure relative to a planar film; ii) out-of-plane BFO C-axis rotation trending from the center towards all released edges of the nanostructure; and iii) an enhancement of local strain variation within the nanostructure of approximately 10 x the variation found within the planar film organized along ferroelectric domain boundaries, as confirmed by piezoresponse-force microscopy (PFM). These results indicate that the release of in-plane BFO/SrRuO3 (SRO) (bottom electrode grown on the single crystal SrTiO3 substrate) mismatch strain in a planar film is taken up by the local ferroelectric domain structure when the BFO nanostructure is patterned, resulting in greatly increased inter-domain mechanical strain gradients within the structure. The findings in this paper may have critical implications for the fabrication of high-density non-volatile ferroelectric random access memories (FeRAMs) based on nanocapacitor structure, and also in general for future multiferroic nanodevices.

  • Reference: J. A. Klug, M. V. Holt, R. Nath Premnath, A. Joshi-Imre, S. Hong, R. S. Katiyar, M. J. Bedzyk, and O. Auciello “Elastic Relaxation and Correlation of Local Strain Gradients with Ferroelectric Domains in (001) BiFeO3 Nanostructures,” Appl. Phys. Lett. 98 (2011) 052902.
  • POC: Orlando Auciello, This e-mail address is being protected from spambots. You need JavaScript enabled to view it. , 630-252-1685