Materials World Network: Critical Scaling of Domain Dynamics in Ferroelectric Nanostructures

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: Research into electronic behavior of ferroelectrics is an important and challenging scientific problem related to fundamental physical properties of complex oxide materials. One of the particularly promising aspects of this research is the dynamic behavior of low-dimensional ferroelectric structures with constrained geometry in the external electric field. For the vast majority of applications, it is the switching and the associated evolution of domain structure that is the cornerstone for device functionality. This research will answer questions related to interplay between complex geometry, size and dynamics of polarization reversal in nanoscale ferroelectric structures and the fundamental scaling limits to ferroelectric-based devices, such as high-density non-volatile memory and data storage devices, spin filters and microwave devices. International student exchange is an essential component of the project contributing to the well-coordinated collaborative research between US and European partners. The UK portion of the work is supported by the Engineering and Physical Sciences Research Council (EPSRC). Students recruited into this project from underrepresented groups, in particular, are benefiting from exposure to international research through the enrichment of their professional preparation and education experience. TECHNICAL DETAILS: This project is investigating and seeking to understand the manner in which reduced size and increased morphological complexity affect the switching behavior of meso- and nanoscale ferroelectrics. The experimental approach involves fabrication of free-standing single-crystalline nanoplates, nanorods and nanodots of a model ferroelectric BaTiO3 and characterization of its dynamic switching behavior by means of an advanced 'stroboscopic' Piezoresponse Force Microscopy (S-PFM) method. The samples are being prepared using a Focused Ion Beam (FIB) technique and then structurally characterized at Queen's University Belfast (QUB), UK, in the group of Prof. John Martin Gregg. Prior research has demonstrated that the FIB mode of fabrication gives particularly clear insight into the fundamental behaviour of ferroelectrics at reduced scales. S-PFM is being used to map the dynamics of domain wall motion during in-plane switching, induced by an external electric field applied between coplanar electrodes. FIB-engineered defects in the thin ferroelectric slabs, such as holes, notches and slits, allow direct studies of the manner in which physical defects alter the nucleation and propagation of domain walls. The outcome of the project will lead to fundamental advances in understanding the role of electrical and mechanical boundary conditions and sample scaling on the basic mechanisms of ferroelectric switching.