Browsing by Author "Strelcov, Evgheni"

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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.
Electrical Modulation of the Local Conduction at Oxide Tubular Interfaces
(2013-10-01)
Hsieh, Ying-Hui
;
Strelcov, Evgheni
;
Liou, Jia-Ming
;
Shen, Chia-Ying
;
Chen, Yi-Chun
Heterointerfaces between complex oxides have sparked considerable interest due to their fascinating physical properties and their offering of new possibilities for next-generation electronic devices. The key to realize practical applications is the control through external stimuli. In this study, we take the self-assembled BiFeO3-CoFe2O4 tubular interface as a model system to demonstrate the nonvolatile electric control of the local conduction at the complex oxide tubular interface. The fundamental mechanism behind this modulation was explored based on static and dynamic conductive atomic force microscopies. We found the movement of oxygen vacancies in the BiFeO3-CoFe2O4 heterostructure is the key to drive this intriguing behavior. This study delivers a possibility in developing next-generation electronic devices.
Probing Local Ionic Dynamics in Functional Oxides at the Nanoscale
(2013-08-01)
Strelcov, Evgheni
;
Kim, Yunseok
;
Jesse, Stephen
;
Cao, Ye
;
Ivanov, Ilia N.
A scanning probe microscopy technique for probing local ionic dynamics in electrochemically active materials based on the first-order reversal curve current-voltage (FORC-IV) method is presented. FORC-IV imaging mode is applied to a Ca-substituted bismuth ferrite (Ca-BFO) system to separate the electronic and ionic phenomena in this material and visualize the spatial variability of these behaviors. The variable-temperature measurements further demonstrate the interplay between the thermally and electric-field-driven resistance changes in Ca-BFO. The FORC-IV is shown to be a simple, powerful, and flexible method for studying electrochemical activity of materials at the nanoscale and, in conjunction with the electrochemical strain microscopy, it can be used for differentiating ferroelectric and ionic behaviors.
Space- and Time-Resolved Mapping of Ionic Dynamic and Electroresistive Phenomena in Lateral Devices
(2013-08-01)
Strelcov, Evgheni
;
Jesse, Stephen
;
Huang, Yen-Lin
;
Teng, Yung-Chun
;
Kravchenko, Ivan I.
A scanning probe microscopy-based technique for probing local ionic and electronic transport and their dynamic behavior on the 10 ms to 10 s scale is presented. The time-resolved Kelvin probe force microscopy (tr-KPFM) allows mapping of surface potential in both space and time domains, visualizing electronic and ionic charge dynamics and separating underlying processes based on their time responses. Here, tr-KPFM is employed to explore the interplay of the adsorbed surface ions and bulk oxygen vacancies and their role in the resistive switching in a Ca-substituted bismuth ferrite thin film.