Synthesis and magnetic characterization of co-axial Ge1-xMnx/a-Si heterostructures
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Accepted version
Date
2011-10-08
Authors
Barth, Sven
Kazakova, Olga
Estrade, Sonia
Hobbes, Richard G.
Piero, Francesca
Morris, Michael A.
Holmes, Justin D.
Journal Title
Journal ISSN
Volume Title
Publisher
American Chemical Society (ACS)
Published Version
Abstract
A method for synthesizing Ge1–xMnx/a-Si core–shell nanowires (x = 0.3(1)–1.0(2)) using a supercritical fluid deposition technique, with a homogeneous distribution of manganese along the entire lengths of the crystalline Ge cores but not in the a-Si shells, is reported. Investigations into the magnetic properties of the heterostructured nanowires revealed a significant influence of the amorphous Si shell covering the surface of the core Ge0.997Mn0.003 nanowires compared to pristine Ge0.997Mn0.003 nanowires with no a-Si coating. The magnetic data revealed diminished values of both the remanence and the saturation magnetization for pristine Mn-doped Ge nanowires at higher temperatures when compared to the Ge1–xMnx/a-Si core–shell nanowires, whereas both parameters increased as the temperature dropped down to 5 K. Differences in the temperature-dependent evolution of the coercivity were observed in the magnetically harder core–shell nanowires compared to the pristine Ge0.997Mn0.003 nanowires, showing a drop of 26% at 5 K vs room temperature compared to a drop of 66% for the pristine nanowires. The low dopant concentration (0.3(1)%) of Mn in the core–shell nanowires, combined with the observed ferromagnetic properties, suggests a combination of hole-mediated exchange and confinement processes are responsible for the observed properties. Our observations show the importance of a protective layer in covering the oxidation-sensitive dilute magnetic semiconductor nanowires.
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Keywords
Germanium , Nanowire , Heterostructure , Core-shell , Magnetic properties , Structural characterization
Citation
Barth, S., Kazakova, O., Estrade, S., Hobbs, R. G., Peiro, F., Morris, M. A. and Holmes, J. D. (2011) 'Synthesis and Magnetic Characterization of Coaxial Ge1–xMnx/a-Si Heterostructures', Crystal Growth & Design, 11(12), pp. 5253-5259.
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Copyright
© 2011 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Crystal Growth & Design copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/abs/10.1021/cg200667r