Coexistence of Weak Ferromagnetism and Ferroelectricity in the High Pressure LiNbO_{3}-Type Phase of FeTiO_{3}

We report the magnetic and electrical characteristics of polycrystalline FeTiO3 synthesized at high pressure that is isostructural with acentric LiNbO3 (LBO). Piezoresponse force microscopy, optical second harmonic generation, and magnetometry demonstrate ferroelectricity at and below room temperature and weak ferromagnetism below ~120??K. These results validate symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LBO structure.

Epitaxial BiFeO3 nanostructures fabricated by differential etching of BiFeO3 films

We report on differential etching behavior of the different orientations of the polarization in BiFeO3 (BFO), similar to other ferroelectrics, such as LiNbO3. We show how this effect can be used to fabricate epitaxial BiFeO3 nanostructures. By means of piezoresponse force microscopy (PFM) domains of arbitrary shape and size can be poled in an epitaxial BiFeO3 film, which are then reproduced in the film morphology by differential etching. Structures with a lateral size smaller than 200 nm were fabricated and very good retention properties as well as a highly increased piezoelectric response were detected by PFM. (C) 2011 American Institute of Physics. [doi:10.1063/1.3630027]