Browsing by Author "Eliseev, E. A."

Now showing 1 - 2 of 2

Atomic-scale evolution of modulated phases at the ferroelectric-antiferroelectric morphotropic phase boundary controlled by flexoelectric interaction
(2012-04-01)
Borisevich, A. Y.
;
Eliseev, E. A.
;
Morozovska, A. N.
;
Cheng, C. -J.
;
Lin, J. -Y.
Physical and structural origins of morphotropic phase boundaries (MPBs) in ferroics remain elusive despite decades of study. The leading competing theories employ either low-symmetry bridging phases or adaptive phases with nanoscale textures to describe different subsets of the macroscopic data, while the decisive atomic-scale information has so far been missing. Here we report direct atomically resolved mapping of polarization and structure order parameter fields in a Sm-doped BiFeO3 system and their evolution as the system approaches a MPB. We further show that both the experimental phase diagram and the observed phase evolution can be explained by taking into account the flexoelectric interaction, which renders the effective domain wall energy negative, thus stabilizing modulated phases in the vicinity of the MPB. Our study highlights the importance of local order-parameter mapping at the atomic scale and establishes a hitherto unobserved physical origin of spatially modulated phases existing in the vicinity of the MPB.
Domain Wall Geometry Controls Conduction in Ferroelectrics
(2012-11-01)
Vasudevan, R. K.
;
Morozovska, A. N.
;
Eliseev, E. A.
;
Britson, J.
;
Yang, J. -C.
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 farmed 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.