Training the Polarization in Integrated La<sub>0.15</sub>Bi<sub>0.85</sub>FeO<sub>3</sub>‐Based Devices
Marvin Müller, Yen‐Lin Huang, Saül Vélez, R. Ramesh, M. Fiebig, Morgan Trassin
Abstract
Abstract The functionalities of BiFeO 3 ‐based magnetoelectric multiferroic heterostructures rely on the controlled manipulation of their ferroelectric domains and of the corresponding net in‐plane polarization, as this aspect guides the voltage‐controlled magnetic switching. Chemical substitution has emerged as a key to push the energy dissipation of the BiFeO 3 into the attojoule range but appears to result in a disordered domain configuration. Using non‐invasive optical second‐harmonic generation on heavily La‐substituted BiFeO 3 films, it is shown that a weak net in‐plane polarization remains imprinted in the pristine films despite the apparent domain disorder. It is found that this ingrained net in‐plane polarization can be trained with out‐of‐plane electric fields compatible with applications. Operando studies on capacitor heterostructures treated in this way show the full restoration of the domain configuration of pristine BiFeO 3 along with a giant net in‐plane polarization enhancement. Thus, the experiments reveal a surprising robustness of the net in‐plane polarization of BiFeO 3 against chemical modification, an important criterion in ongoing attempts to integrate magnetoelectric materials into energy‐efficient devices.