Simple synthesis and characterization of vertically aligned Ba_0.7Sr_0.3TiO₃–CoFe₂O₄multiferroic nanocomposites from CoFe₂nanopillar arrays

Abstract

A new strategy to elaborate (1-3) type multiferroic nanocomposites with controlled dimensions and vertical alignment is presented. The process involves a supported nanoporous alumina layer as a template for growth of free-standing and vertically aligned CoFe₂ nanopillars using a room temperature pulsed electrodeposition process. Ba_0.70Sr_0.30TiO₃-CoFe₂O₄ multiferroic nanocomposites were grown through direct deposition of Ba_0.7Sr_0.3TiO₃ films by radio-frequency sputtering on the top surface of the pillar structure, with in situ simultaneous oxidation of CoFe₂ nanopillars. The vertically aligned multiferroic nanocomposites were characterized using various techniques for their structural and physical properties. The large interfacial area between the ferrimagnetic and ferroelectric phases leads to a magnetoelectric voltage coefficient as large as ∼320 mV cm^-1 Oe^-1 at room temperature, reaching the highest values reported so far for vertically architectured nanocomposite systems. This simple method has great potential for large-scale synthesis of many other hybrid vertically aligned multiferroic heterostructures.