Magnetic and Structural Properties of Co5Ge3 Nanoparticles.

ORAL

Abstract

Magnetic semiconductor alloy nanostructures play a crucial role in advanced technologies due to their tunable band gaps and electronic properties. Among these magnetic semiconductor alloys, Co-Ge is important both scientifically and technologically. In this work, we studied the magnetic and transport properties of Co$_{5}$Ge$_{3\, }$nanoparticles(NPs) fabricated by cluster-beam deposition. The NPs were characterized by X-ray powder diffraction and the results demonstrated that they had the same hexagonal structure P63/mm-type as in bulk.Transmission-electron-microscope observations revealed that the particles have a single crystalline structure with an average size of 8nm. Selected-area electron diffraction(SAED) confirmed the XRD data, showing clearly that the particles have the hexagonal structure mentioned above. High-resolution electron microscopy images show lattice fringes with spacing of 1.99A and 2.02A which correspond to the (102) and (110) superlattice reflections of the hexagonal ordered Co$_{5}$Ge$_{3}$ structure. Magnetic properties showed that these nanoparticles are ferromagnetic at room temperature as-compared to bulk samples that are paramagnetic at all temperatures. This magnetic behavior in Co-Ge nanoparticles indicates new size-controlled spin structures in confined nanosize systems.

*Work supported by DOE DE-FG02-04ERU4612and DE-FG02-04ER46152.

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Authors

  • Mohammad Salehi-Fashami

    • University of Delaware
    • Univ of Delaware

  • Vimal Deepchand

    • University of Delaware

  • Ralph Skomski

    • University of Nebraska–Lincoln

  • D. J. Sellmyer

    • Nebraska Center for Materials and Nanoscience and Department of Physics and Astronomy, University of Nebraska
    • University of Nebraska–Lincoln
    • Physics and Astronomy and NCMN, University of Nebraska
    • Univ of Nebraska-Lincoln
    • University of Nebraska Lincoln
    • University of Nebraska, Lincoln
    • Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588

  • George C Hadjipanayis

    • University of Delaware
    • Physics and Astronomy, University of Delaware
    • Univ of Delaware
    • Department of Physics and Astronomy, University of Delaware, Newark, DE, USA