This project was funded by eScience.

The objectives of the proposed project are four-fold:

  1. To fabricate interface dominated multiferroic nanostructures (IDMNS), and explore their potential applications as spintronics and energy storage and conversion devices.
  2. To characterize the properties of as-synthesized IDMNS for probing the magnetoelectric (ME) coupling and unique properties arising from interface-mediated effects.
  3. To establish a multi-scale modeling framework for determining the ME coupling behavior in IDMNS using multiferroic nano-composites (MNCS) as an example.
  4. To optimize the IDMNS architecture for making high performance prototype devices, e.g., larger ME coupling and enhanced unique interfacial properties, by iterating the process of fabrication, characterization and modeling.

The long term impact of the proposed project is described below.

  1. Key issues and problems being addressed

    The experimental study consisting of fabrication, characterization and device exploration cum modulation will provide a comprehensive solution for the promising applications of IDMNS in spintronics, and in the field of energy storage and conversion since the abundant interfaces of IDMNS can provide sufficient electric dipoles and areas for the storage and conversion from hydrogen molecules to ions1,2. The fabrication method for IDMNS will be evaluated first. Subsequently, by combining the results of first principles calculations and experimental characterization, the components and structures of IDMNS will be optimized for attaining larger

    ME coupling and other possible unique properties. As for numerical studies, the key issue is the consideration of interfacial effects in nano-/micro-scale multiferroic modeling, in which polarization and magnetization are the two order-parameters to be coupled.

    A multi-scale modeling framework will be established. At nanoscale, a phase field model will be developed to evaluate the domain structures of the system; at micro-scale, an energy approach will be used to study the interfacial influences on the ME effect of the system; and finally, a micromechanics theory will be established to tackle the physical properties/structure relations of MNCS. The developed theory will be able to predict the optimized nano-/micro-structure and size effects on the ME coupling behavior of MNCS.

  2. Possible outcome

    Upon successful completion of the project, the interfacial effects on the ME coupling behavior and the induced novel properties will be better understood. Moreover, the approach to optimize the IDMNS for maximizing the ME coupling effect and/or other unique properties will also be established. The potential applications of IDMNS will also be explored and developed.

SEM, TEM images, EDX spectrum and scanning TEM elemental maps of as-synthesized nanowire arrays

SEM, TEM images, EDX spectrum and scanning TEM elemental maps of as-synthesized nanowire arrays. (a) SEM image; (b) EDX spectrum; (c) TEM image of single nanowire and the inserted picture is its SAED pattern; (d) scanning TEM elemental maps of a CoxGd1-x nanowire.

References

  1. Zhou, J., Wang, Q., Sun, Q., et al., Proc. Natl. Acad. Sci. U. S. A. 107, 2801-2806 (2010).
  2. Minnear, System and method for storing hydrogen and electrical energy. US patent (2009).