Nanoscale control of phase variants in strain-engineered BiFeO₃.

Vasudevan, Rama K; Liu, Yunya; Li, Jiangyu; Liang, Wen-I; Kumar, Amit; Jesse, Stephen; Chen, Yi-Chun; Chu, Ying-Hao et al. · Nano Lett · 2011

basic_science · Level V

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Abstract

Development of magnetoelectric, electromechanical, and photovoltaic devices based on mixed-phase rhombohedral-tetragonal (R-T) BiFeO(3) (BFO) systems is possible only if the control of the engineered R phase variants is realized. Accordingly, we explore the mechanism of a bias induced phase transformation in this system. Single point spectroscopy demonstrates that the T → R transition is activated at lower voltages compared to T → -T polarization switching. With phase field modeling, the transition is shown to be electrically driven. We further demonstrate that symmetry of formed R-phase rosettes can be broken by a proximal probe motion, allowing controlled creation of R variants with defined orientation. This approach opens a pathway to designing next-generation magnetoelectronic and data storage devices in the nanoscale.