Impact of magnetization and hyperfine field distribution on high magnetoelectric coupling strength in BaTiO3–BiFeO3 multilayers

Abstract

Correlations were established between the hyperfine field distribution around the Fe atoms, the multiferroic properties, and the high magnetoelectric coefficient in BaTiO₃–BiFeO₃ multilayer stacks with variable BiFeO₃ single layer thickness, down to 5 nm. Of key importance in this study was the deposition of ⁵⁷Fe – enriched BiFeO₃, which enhances the sensitivity of conversion electron Mössbauer spectroscopy by orders of magnitude. The magnetoelectric coefficient α_ME reaches a maximum of 60.2 V cm⁻¹ Oe⁻¹ at 300 K and at a DC bias field of 2 Tesla for a sample of 15 × (10 nm BaTiO₃–5 nm BiFeO₃) and is one of the highest values reported so far. Interestingly, the highest α_ME 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.