Jun 29, 2010
Self-assembled magnetic nanostructures enable future spintronic devices
Lattice-coherent magnetic nanostructures would facilitate spin injections into traditional semiconductors because of less interface scattering and a small conductivity mismatch. Precise control of these nanostructures holds the key to achieving future spintronic and magnetoelectronic devices.
However, creating controllable magnetic nanostructures is rather challenging, particularly considering the random nucleation of these nanostructures. Researchers at the University of California at Los Angeles, US, and the University of Queensland, Australia, have taken a major step towards the manipulative production of MnGe magnetic nanostructures by using a "superlattice" growth approach.
In essence, MnGe and Ge layers can be alternately grown on GaAs substrates. When the growth temperature and thickness of MnGe and Ge are properly designed, the MnGe nanostructures, such as nanowells and nanocolumns, are successfully fabricated via a self-assembly process, as shown in the figure. One of the striking characteristics of these lattice-coherent nanostructures is the distinct magnetoresistance under a magnetic field. It is shown that the nanowells have large and positive magnetoresistance while the nancolumns exhibit negative magnetoresistance.
Because the MnGe nanostructures are embedded in the Ge matrix, this material system combines both the magnetic properties from the MnGe nanostructures and important semiconductor characteristics, providing an extraordinary material candidate for the development of future spin electronic devices.
More information can be found in the journal Nanotechnology.
About the author
Faxian Xiu, PhD, is a senior postdoctoral fellow at the Device Research Laboratory, UCLA (http://drl.ee.ucla.edu/). He primarily focuses on MnGe growth and spintronic devices. The research group is led by Raytheon Chair Professor Kang L Wang, who also serves as director of the Center on Functional Engineered Nano Architectonics (FENA, www.fena.org/) and is an executive member of the Western Institute of Nanotechnology (WIN, www.win-nano.org/). The TEM collaborators, Dr Yong Wang and Prof. Jin Zou, are from the Center for Microscopy and Microanalysis at the University of Queensland. They contributed significantly to this work.