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Synthesis and magnetic characterization of Coaxial Ge(1-x)Mn(x)/a-Si heterostructures.

Barth, S*; Kazakova, O; Estrade, S*; Hobbs, R G*; Peiro, F*; Morris, M A*; Holmes, J D* (2011) Synthesis and magnetic characterization of Coaxial Ge(1-x)Mn(x)/a-Si heterostructures. Cryst. Growth Des., 11 (12). pp. 5253-5259.

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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 these 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. RT) 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 the hole-mediated exchange and confinement processes as a reason for the observed properties. Our observations show the importance of a protective layer in covering the oxidation-sensitive dilute magnetic semiconductor nanowires.

Item Type: Article
Subjects: Nanoscience
Nanoscience > Nano-Materials
Identification number/DOI: 10.1021/cg200667r
Last Modified: 02 Feb 2018 13:14
URI: http://eprintspublications.npl.co.uk/id/eprint/5339

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