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Title: Local conductance: A means to extract polarization and depolarizing fields near domain walls in ferroelectrics

Abstract

Conducting atomic force microscopy images of bulk semiconducting BaTiO{sub 3} surfaces show clear stripe domain contrast. High local conductance correlates with strong out-of-plane polarization (mapped independently using piezoresponse force microscopy), and current-voltage characteristics are consistent with dipole-induced alterations in Schottky barriers at the metallic tip-ferroelectric interface. Indeed, analyzing current-voltage data in terms of established Schottky barrier models allows relative variations in the surface polarization, and hence the local domain structure, to be determined. Fitting also reveals the signature of surface-related depolarizing fields concentrated near domain walls. Domain information obtained from mapping local conductance appears to be more surface-sensitive than that from piezoresponse force microscopy. In the right materials systems, local current mapping could therefore represent a useful complementary technique for evaluating polarization and local electric fields with nanoscale resolution.

Authors:
; ;  [1];  [2]
  1. Centre for Nanostructured Media, School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN (United Kingdom)
  2. Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom)
Publication Date:
OSTI Identifier:
22485970
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ATOMIC FORCE MICROSCOPY; BARIUM COMPOUNDS; CURRENTS; DIPOLES; DOMAIN STRUCTURE; ELECTRIC FIELDS; ELECTRIC POTENTIAL; FERROELECTRIC MATERIALS; IMAGES; NANOSTRUCTURES; POLARIZATION; RESOLUTION; SURFACES; TITANATES; VARIATIONS

Citation Formats

Douglas, A. M., Kumar, A., Gregg, J. M., and Whatmore, R. W. Local conductance: A means to extract polarization and depolarizing fields near domain walls in ferroelectrics. United States: N. p., 2015. Web. doi:10.1063/1.4934833.
Douglas, A. M., Kumar, A., Gregg, J. M., & Whatmore, R. W. Local conductance: A means to extract polarization and depolarizing fields near domain walls in ferroelectrics. United States. doi:10.1063/1.4934833.
Douglas, A. M., Kumar, A., Gregg, J. M., and Whatmore, R. W. Mon . "Local conductance: A means to extract polarization and depolarizing fields near domain walls in ferroelectrics". United States. doi:10.1063/1.4934833.
@article{osti_22485970,
title = {Local conductance: A means to extract polarization and depolarizing fields near domain walls in ferroelectrics},
author = {Douglas, A. M. and Kumar, A. and Gregg, J. M. and Whatmore, R. W.},
abstractNote = {Conducting atomic force microscopy images of bulk semiconducting BaTiO{sub 3} surfaces show clear stripe domain contrast. High local conductance correlates with strong out-of-plane polarization (mapped independently using piezoresponse force microscopy), and current-voltage characteristics are consistent with dipole-induced alterations in Schottky barriers at the metallic tip-ferroelectric interface. Indeed, analyzing current-voltage data in terms of established Schottky barrier models allows relative variations in the surface polarization, and hence the local domain structure, to be determined. Fitting also reveals the signature of surface-related depolarizing fields concentrated near domain walls. Domain information obtained from mapping local conductance appears to be more surface-sensitive than that from piezoresponse force microscopy. In the right materials systems, local current mapping could therefore represent a useful complementary technique for evaluating polarization and local electric fields with nanoscale resolution.},
doi = {10.1063/1.4934833},
journal = {Applied Physics Letters},
number = 17,
volume = 107,
place = {United States},
year = {Mon Oct 26 00:00:00 EDT 2015},
month = {Mon Oct 26 00:00:00 EDT 2015}
}
  • Simple meso-scale capacitor structures have been made by incorporating thin (∼300 nm) single crystal lamellae of KTiOPO{sub 4} (KTP) between two coplanar Pt electrodes. The influence that either patterned protrusions in the electrodes or focused ion beam milled holes in the KTP have on the nucleation of reverse domains during switching was mapped using piezoresponse force microscopy imaging. The objective was to assess whether or not variations in the magnitude of field enhancement at localised “hot-spots,” caused by such patterning, could be used to both control the exact locations and bias voltages at which nucleation events occurred. It was found thatmore » both the patterning of electrodes and the milling of various hole geometries into the KTP could allow controlled sequential injection of domain wall pairs at different bias voltages; this capability could have implications for the design and operation of domain wall electronic devices, such as memristors, in the future.« less
  • Electrically conducting interfaces can form, rather unexpectedly, by breaking the translational symmetry of electrically insulating complex oxides. For example, a nanometre-thick heteroepitaxial interface between electronically insulating LaAlO 3 and SrTiO 3 supports a 2D electron gas1 with high mobility of >1,000 cm 2 V -1 s -1 (ref. 2). Such interfaces can exhibit magnetism, superconductivity and phase transitions that may form the functional basis of future electronic devices2. A peculiar conducting interface can be created within a polar ferroelectric oxide by breaking the translational symmetry of the ferroelectric order parameter and creating a so-called ferroelectric domain wall (Fig. 1a,b). Ifmore » the direction of atomic displacements changes at the wall in such a way as to create a discontinuity in the polarization component normal to the wall (Fig. 1a), the domain wall becomes electrostatically charged. It may then attract compensating mobile charges of opposite sign produced by dopant ionization, photoexcitation or other effects, thereby locally, electrostatically doping the host ferroelectric film. In contrast to conductive interfaces between epitaxially grown oxides, domain walls can be reversibly created, positioned and shaped by electric fields, enabling reconfigurable circuitry within the same volume of the material. Now, writing in Nature Nanotechnology, Arnaud Crassous and colleagues at EPFL and University of Geneva demonstrate control and stability of charged conducting domain walls in ferroelectric thin films of BiFeO 3 down to the nanoscale.« less
  • We have measured the time dependence of the polarization of a stored proton beam near an intrinsic depolarizing resonance. The distance to the resonance was varied by changing the vertical tune of the storage ring. The measurements are consistent with exponential decay and with a simple model for the change of the lifetime as the resonance is approached. It was originally expected that the presence of an internal target stimulates depolarization; however, we found no evidence for such an effect. {copyright} {ital 1997} {ital The American Physical Society}
  • The time dependence of the polarization of a stored proton beam was measured near an induced depolarizing resonance. The resonance was created by a magnetic field which oscillated along the beam axis. The distance to the resonance was varied by changing the frequency of the oscillating field. The resonance was approached from either side and the time dependence of the polarization was found to be symmetric with respect to the resonance, and in agreement with an earlier measurement that involved an intrinsic depolarizing resonance. {copyright} {ital 1998 American Institute of Physics.}