Domain Wall Geometry Controls Conduction in Ferroelectrics

Abstract

A new paradigm of domain wall nanoelectronics has emerged recently, in which the domain wall in a ferroic is itself an active device element. The ability to spatially modulate the ferroic order parameter within a single domain wall allows the physical properties to be tailored at will and hence opens vastly unexplored device possibilities. Here, we demonstrate via ambient and ultrahigh-vacuum (UHV) scanning probe microscopy (SPM) measurements in bismuth ferrite that the conductivity of the domain walls can be modulated by up to 500% in the spatial dimension as a function of domain wall curvature. Landau-Ginzburg-Devonshire calculations reveal the conduction is a result of carriers or vacancies migrating to neutralize the charge at the formed interface. Phase-field modeling indicates that anisotropic potential distributions can occur even for initially uncharged walls, from polarization dynamics mediated by elastic effects. These results are the first proof of concept for modulation of charge as a function of domain wall geometry by a proximal probe, thereby expanding potential applications for oxide ferroics in future nanoscale electronics.

Electric control of straight stripe conductive mixed-phase nanostructures in La-doped BiFeO3

“…23,24,[30][31][32] Electric fields formed by applying a negative voltage to the tip are composed of in-plane components converging inward at the tip as well as an out-of-plane directional field component. During tip scanning, the electric fields along the fast scan axis countervail each other; even the in-plane electric field antiparallel to the slow scan direction does not have the final influence on the mixed-phase formation because the written effect is erased and reversed by the opposite field in the next several line scans.…”

Rewritable ferroelectric vortex pairs in BiFeO3

“…4 Besides, the individual magnetic skyrmions can be created and annihilated, which demonstrates the potential for topological charge in future information-storage concepts. 5 In condensed matter systems, the study of topological defects is crucial to ferroic materials, such as the conductivity of domain walls, [6][7][8] and the electric field manipulating and imprinting of ferroelectric domains into ferromagnets. 9,10 In recent years, a wide spectrum of ferroelectric vortices have been investigated in the forms of nanostructure, epitaxial thin film, oxide superlattice and single crystal, in which the vortices are widespread in ferroelectric systems with perovskite structure.…”

Polarization control at spin-driven ferroelectric domain walls

“…In particular, the polarity mismatch at charged walls leads to characteristics that clearly distinguish them from the interior of the domains they separate [1][2][3][4] . Such ferroelectric domain walls can behave as a two-dimensional insulator 5 , become metallic 6,7 , show orientation-dependent electrical conductance [8][9][10] or anisotropic magnetoresistance 11 , even when the bulk material has none of these properties. Exotic domain-wall phenomena are observed in archetypal ferroelectrics, such as BaTiO 3 (refs 12,13), PbZr 0.2 Ti 0.8 O 3 (refs 7,14,15) and LiNbO 3 (ref.…”