Contact-free reversible switching of improper ferroelectric domains by electron and ion irradiation

Abstract

Focused ion beam (FIB) and scanning electron microscopy (SEM) are used to reversibly switch improper ferroelectric domains in the hexagonal manganite ErMnO 3 . Surface charging is achieved by local ion (positive charging) and electron (positive and negative charging) irradiation, which allows controlled polarization switching without the need for electrical contacts. Polarization cycling reveals that the domain walls tend to return to the equilibrium configuration obtained in the as-grown state. The electric field response of sub-surface domains is studied by FIB cross-sectioning, revealing the 3D switching behavior. The results clarify how the polarization reversal in hexagonal manganites progresses at the level of domains, resolving both domain wall movements and the nucleation and growth of new domains. Our FIB-SEM based switching approach is applicable to all ferroelectrics where a sufficiently large electric field can be built up via surface charging, facilitating contact-free high-resolution studies of the domain and domain wall response to electric fields in 3D.

Magnetoelastic properties of multiferroic hexagonal ErMnO3

“…A degree of mobility for ferroelectric domain walls at room temperature is also implied by the observation of Han et al [65] and Roede et al [62] that the configuration of domains induced at the surface of a crystal of ErMnO3 by application of external electric field relaxed back to the original configuration when the field was removed.…”

“…The possible role of defects in pinning domain walls has been considered in detail for hexagonal manganites [61,62], while patterns of acoustic loss at kHz/MHz frequencies have provided insights into the dynamics of point defects and microstructures that are coupled with strain, as seen in numerous examples of freezing/pinning of ferroelastic twin walls in perovskites [41]. None of the domain walls in ErMnO3 have a ferroelastic component, however, and they therefore should not be mobile under the influence of an externally applied shear stress.…”