Impact of magnetization and hyperfine field distribution on high magnetoelectric coupling strength in BaTiO-BiFeO multilayers.

Correlations were established between the hyperfine field distribution around the Fe atoms, the multiferroic properties, and the high magnetoelectric coefficient in BaTiO-BiFeO multilayer stacks with variable BiFeO single layer thickness, down to 5 nm. Of key importance in this study was the deposition of Fe - enriched BiFeO, which enhances the sensitivity of conversion electron Mössbauer spectroscopy by orders of magnitude. The magnetoelectric coefficient α reaches a maximum of 60.2 V cm Oe at 300 K and at a DC bias field of 2 Tesla for a sample of 15 × (10 nm BaTiO-5 nm BiFeO) and is one of the highest values reported so far. Interestingly, the highest α is connected to a high asymmetry of the hyperfine field distribution of the multilayer composite samples. The possible mechanisms responsible for the strong magnetoelectric coupling are discussed.