🏛️國立陽明交通大學機構典藏

Search Results

Now showing 1 - 4 of 4

Deep Data Analysis of Conductive Phenomena on Complex Oxide Interfaces: Physics from Data Mining
(2014-06-01)
Strelcov, Evgheni
;
Belianinov, Alexei
;
Hsieh, Ying-Hui
;
Jesse, Stephen
;
Baddorf, Arthur P.
Spatial variability of electronic transport in BiFeO3-CoFe2O4 (BFO-CFO) self-assembled heterostructures is explored using spatially resolved first-order reversal curve (FOR) current voltage (IV) mapping. Multivariate statistical analysis of FORC-IV data classifies statistically significant behaviors and maps characteristic responses spatially. In particular, regions of grain, matrix, and grain boundary responses are clearly identified, k-Means and Bayesian demixing analysis suggest the characteristic response be separated into four components, with hysteretic-type behavior localized at the BFO-CFO tubular interfaces. The conditions under which Bayesian components allow direct physical interpretation are explored, and transport mechanisms at the grain boundaries and individual phases are analyzed. This approach conjoins multivariate statistical analysis with physics-based interpretation, actualizing a robust, universal, data-driven approach to problem solving, which can be applied to exploration of local transport and other functional phenomena in other spatially inhomogeneous systems.
Probing Local Electromechanical Effects in Highly Conductive Electrolytes
(2012-11-01)
Balke, Nina
;
Tselev, Alexander
;
Arruda, Thomas M.
;
Jesse, Stephen
;
Chu, Ying-Hao
The functionality of a variety of materials and devices is strongly coupled with electromechanical effects which can be used to characterize their functionality. Of high interest is the investigation of these electromechanical effects on the nanoscale which can be achieved by using scanning probe microscopy. Here, an electrical bias is applied locally to the scanning probe tip, and the mechanical sample response is detected. In some applications with electromechanical phenomena, such as energy storage or for biological samples, a liquid environment is required to provide full functionality and sample stability. However, electromechanical sample characterization has mostly been applied in air or under vacuum due to the difficulties of applying local electric fields in a conductive environment. Here, we present a detailed study of piezoresponse force microscopy of ferroelectric samples in liquid environments as a model system for electromechanical effects in general. The ionic strength of the liquid is varied, and possibilities and limitations of the technique are explored. Numerical simulations are used to explain the observed phenomena and used to suggest strategies to work in liquid environments with high ionic strength.
High-Frequency Electromechanical Imaging of Ferroelectrics in a Liquid Environment
(2012-06-01)
Balke, Nina
;
Jesse, Stephen
;
Chu, Ying-Hao
;
Kalinin, Sergei V.
;
材料科學與工程學系
The coupling between electrical and mechanical phenomena is a ubiquitous feature of many information and energy storage materials and devices. In addition to involvement in performance and degradation mechanisms, electromechanical effects underpin a broad spectrum of nanoscale imaging and spectroscopies including piezoresponse force and electrochemical strain microscopies. Traditionally, these studies are conducted under ambient conditions. However, applications related to imaging energy storage and electrophysiological phenomena require operation in a liquid phase and therefore the development of electromechanical probing techniques suitable to liquid environments. Due to the relative high conductivity of most liquids and liquid decomposition at low voltages, the transfer of characterization techniques from ambient to liquid is not straightforward. Here we present a detailed study of ferroelectric domain imaging and manipulation in thin film BiFeO3 using piezoresponse force microscopy in liquid environments as model systems for electromechanical phenomena in general. We explore the use of contact resonance enhancement and the application of multifrequency excitation and detection principles to overcome the experimental problems introduced by a liquid environment. Understanding electromechanical sample characterization in liquid is a key aspect not only for ferroelectric oxides but also for biological and electrochemical sample systems.
Tunable Metallic Conductance in Ferroelectric Nanodomains
(2012-01-01)
Maksymovych, Peter
;
Morozovska, Anna N.
;
Yu, Pu
;
Eliseev, Eugene A.
;
Chu, Ying-Hao
Metallic conductance in charged ferroelectric domain walls was predicted more than 40 years ago as the first example of an electronically active homointerface in a nonconductive material. Despite decades of research on oxide interfaces and ferroic systems, the metal-insulator transition induced solely by polarization charges without any additional chemical modification has consistently eluded the experimental realm. Here we show that a localized insulator-metal transition can be repeatedly induced within an insulating ferroelectric lead-zirconate titanate, merely by switching its polarization at the nanoscale. This surprising effect is traced to tilted boundaries of ferroelectric nanodomains, that act as localized homointerfaces within the perovskite lattice, with inherently tunable carrier density. Metallic conductance is unique to nanodomains, while the conductivity of extended domain walls and domain surfaces is thermally activated. Foreseeing future applications, we demonstrate that a continuum of nonvolatile metallic states across decades of conductance can be encoded in the size of ferroelectric nanodomains using electric field.

學術出版;;Publications

Browse

Filters

Settings

Sort By

Results per page

🏛️國立陽明交通大學機構典藏

Search Results