Probing local ionic dynamics in functional oxides at the nanoscale.

Strelcov, Evgheni; Kim, Yunseok; Jesse, Stephen; Cao, Ye; Ivanov, Ilia N; Kravchenko, Ivan I; Wang, Chih-Hung; Teng, Yung-Chun et al. · Nano Lett · 2013

basic_science · Level V

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Abstract

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.