Control of exotic domain structures in ferroelectric nanopillars by an electric field

Abstract

Nanoscale ferroic materials have attracted considerable interest due to their novel properties including electronic, electromechanical and magnetoelectric properties different from bulk properties. Until now, exotic ferroelectric structures have been described theoretically such as flux-closure domains, but experimental studies for ferroelectric multi-domains in nanostructures have been a lack of research due to their large domain wall energy. Our experiments can be divided into two major sections. First, we explored ferroelectric nanopillars under strain relaxation. In the as-grown state, there are four classes of domain structures. Each domain structure is switchable to other domain types by tip-based non-local switching methods whereby local electric polarization switching can affect distant domain regions to minimize free energy. Second, we report growth of ferromagnetic nanopillars on (001)-, (110)-, (111)-oriented $SrTiO_3$ (STO) substrates. Our results show that CFO nanopillars are of rectangular, stripe, triangular shapes embedded in BFO matrixes on (001)-, (110)-, (111)-oriented STO substrates, respectively. Moreover, we observe that the size of CFO nanopillars depends on growth temperature and laser repetition rate. Our findings provide a useful insight into ferroelectric nano-scale multi-domain structures.