Argonne National Laboratory

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Growth and Patterning of Epitaxial Multiferroic Nanocomposites Using Pulsed Electron Deposition

Materials Science Seminar
Ryan Comes, University of Virginia
November 28, 2012 2:00PM to 3:00PM
Building 223, Room S105
CoFe2O4 (CFO) offers unique properties as a magnetoelectric material due to its large magnetoelastic response when strained. Previous work has shown that when CFO is co-deposited with BiFeO3 (BFO) nanostructured phase segregation occurs, with CFO pillars forming in a BFO matrix, and that electrical control of the magnetic anisotropy is possible.[1]

The CFO-BFO nanocomposite system has been proposed as a possible electrically-controlled spintronic logic or memory scheme.[2] In this talk, I will discuss work I have performed at UVA as part of my dissertation to grow and pattern high quality CFO-BFO nanocomposites using the novel pulsed electron-beam deposition (PED) technique.[3]

The relatively new PED technique is similar to the more traditional pulsed laser deposition (PLD) approach, but steps must be taken to ensure good film quality. I will briefly discuss how we have optimized the PED growth process to achieve layer-by-layer epitaxial growth of complex oxides. I will then discuss our work growing CFO-BFO nanocomposites using PED and explain the difference in magnetic properties that we see due to the different growth technique.

Then I will discuss the new technique we have developed to direct the self-assembly of the CFO pillars in CFO-BFO nanocomposites using electron-beam lithography. [4] Our recent results have demonstrated the ability to pattern the nanocomposites into square arrays of pillars with pillar spacing as small as 100 nm.

[1] F.Zavaliche, et al. Nano Lett. 7 (2007).
[2] S.A. Wolf, et al. Proc. IEEE 98 (2010).
[3] R. Comes, et al. J. App. Phys. 111 (2012).
[4] R. Comes, et al. Nano Lett. 12 (2012).