Self-assembled multiferroic perovskite–spinel nanocomposite thin films: epitaxial growth, templating and integration on silicon
This review describes recent progress in the growth and properties of self-assembled multiferroic perovskite–spinel nanocomposite thin films, in particular, BiFeO3–CoFe2O4, and their integration on silicon or pre-patterned substrates. Vertically aligned nanocomposite thin films, in which ferromagnetic spinel CoFe2O4 nanopillars grow in a ferroelectric perovskite BiFeO3 matrix, have been investigated for applications such as next generation memory devices. The strain transfer between the two oxide phases at the vertical interface enables cross-coupling of the properties, i.e. a magnetic (electric) field can modify the polarization (magnetization) state, making the nanocomposite a two-phase magnetoelectric multiferroic. The ability to grow high quality thin film nanocomposites and the control of their properties through epitaxial strain transfer are prerequisites for their incorporation into practical devices. Most work has been carried out on perovskite substrates using pulsed laser deposition, and integration on semiconductor-compatible substrates using scalable deposition processes presents a challenge. This review focuses on the epitaxial integration of BiFeO3–CoFe2O4 nanocomposite thin films using sputter deposition on silicon substrates, and discusses recent work on the formation of highly ordered nanocomposites using various template patterning methods. This robust, scalable route for large-area fabrication of multifunctional oxide nanocomposites using sputtering brings the exciting prospects offered by these materials closer towards technological realization.
- This article is part of the themed collection: Recent Review Articles