Polymer-templated chemical solution deposition of ferrimagnetic nanoarrays and multiferroic nanocomposite thin films

Multiferroic composites that combine the ferromagnetic and ferroelectric materials not only preserve the characters of the parent materials but also have a high potential for the interplay between the two ferroic orders. This interplay, known as magnetoelectric (ME) coupling, opens the door to a new type of applications, such as multi-state memories, electric-write magnetic-read hard disk drives (HDDs), and magnetic field sensors.
With the ongoing trend towards device miniaturization, patterning (one of) the ferroic phases into ordered nanoarrays in thin films becomes increasingly desirable. The prevailing fabrication method so far is pulsed laser deposition (PLD), which requires expensive equipment. This thesis demonstrates a low-cost alternative, which is based on chemical solution deposition and utilizes polymer thin films as templates. Highly ordered arrays of ferrimagnetic oxide nanoarrays were first fabricated on Si substrates, and transformed into nanocomposites by simply spin-coating a ferroelectric thin layer. All composites were proven multiferroic at room temperature. A ME coupling effect was demonstrated at room temperature as well. With its low cost, flexibility on pattern design, substrate, and material choices, we believe this approach can be easily extended to the fabrication of many other nanocomposite systems.