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Observation of Strong Polarization Enhancement in Ferroelectric Tunnel Junctions



Linze Li, Xiaoxing Cheng, Thomas Blum, Huaixun Huyan, Yi Zhang, Colin A. Heikes, Xingxu Yan, Chaitanya Gadre, Toshihiro Aoki, Mingjie Xu, Lin Xie, Zijian Hong, Carolina Adamo, Darrell G. Schlom, Long-Qing Chen, Xiaoqing Pan


Ferroelectric heterostructures, with capability of storing data at ultrahigh densities, could act as the platform for next-generation memories. The development of new device paradigms has been hampered by the long-standing notion of inevitable ferroelectricity suppression under reduced dimensions. Despite recent experimental observation of stable polarized states in ferroelectric ultrathin films, the out-of-plane polarization components in these films are strongly attenuated compared to thicker films, implying a degradation of device performance in electronic miniaturization processes. Here, in a model system of BiFeO3/La0.7Sr0.3MnO3, we report observation of a dramatic out-of-plane polarization enhancement that occurs with decreasing film thickness. Our electron microscopy analysis coupled with phase-field simulations reveals a polarization-enhancement mechanism that is dominated by the accumulation of oxygen vacancies at interfacial layers. The results shed light on the interplay between polarization and defects in nanoscale ferroelectrics and suggest a route to enhance functionality in oxide devices.
Nano Letters


Ferroelectric Tunnel Junctions, ultrathin films, polarization enhancement, oxygen vacancies, transmission electron microscopy, multiferroics


Li, L. , Cheng, X. , Blum, T. , Huyan, H. , Zhang, Y. , Heikes, C. , Yan, X. , Gadre, C. , Aoki, T. , Xu, M. , Xie, L. , Hong, Z. , Adamo, C. , Schlom, D. , Chen, L. and Pan, X. (2019), Observation of Strong Polarization Enhancement in Ferroelectric Tunnel Junctions, Nano Letters, [online], (Accessed March 2, 2024)
Created October 8, 2019, Updated October 12, 2021