Probing surface and bulk electrochemical processes on the LaAlO3-SrTiO3 interface.

Kumar, Amit; Arruda, Thomas M; Kim, Yunseok; Ivanov, Ilia N; Jesse, Stephen; Bark, Chung W; Bristowe, Nicholas C; Artacho, Emilio et al. · ACS Nano · 2012

basic_science · Level V

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Abstract

Local electrochemical phenomena on the surfaces of the LaAlO(3)-SrTiO(3) heterostructure are explored using unipolar and bipolar dynamic electrochemical strain microscopy (D-ESM). The D-ESM suggests the presence of at least two distinct electrochemical processes, including fast reversible low-voltage process and slow high-voltage process. The latter process is associated with static surface deformations in the sub-nanometer regime. These behaviors are compared with Kelvin probe force microscopy hysteresis data. The possible origins of observed phenomena are discussed, and these studies suggest that charge-writing behavior in LAO-STO includes a strong surface/bulk electrochemical component and is more complicated than simple screening by surface adsorbates.