Simple synthesis and characterization of vertically aligned Ba 0.7 Sr 0.3 TiO 3 -CoFe 2 O 4 multiferroic nanocomposites from CoFe 2 nanopillar arrays.

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 CoFe ₂ nanopillars using a room temperature pulsed electrodeposition process. Ba _0.70 Sr _0.30 TiO ₃ -CoFe ₂ O ₄ multiferroic nanocomposites were grown through direct deposition of Ba _0.7 Sr _0.3 TiO ₃ films by radio-frequency sputtering on the top surface of the pillar structure, with in situ simultaneous oxidation of CoFe ₂ 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.