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(Color online) Auger electron spectroscopy measurements performed on the as-implanted Ge:Mn and the PLA Ge:Mn. The measurements with a 15 μm broad electron beam (15 μm AES) show a clear segregation of Mn towards the surface. Locally (1 μm AES) there exists also a slightly different Mn-distribution after PLA due to the lateral annealing periodicity of 10 μm. The inset shows the temperature dependent magnetic remanence of the Ge:Mn film after PLA from temperature dependent SQUID measurements.
TEM images of Mn implanted Ge annealed with PLA. (a) In the high resolution XTEM image, an approx. 4 nm thick polycrystalline layer is visible on top of the Ge:Mn film (1). The tadpole-shaped precipitate (2) is embedded in the crystalline Ge:Mn matrix (3). The white lines are guides to the eye. (b) An overview over nearly regularly distributed tadpole-shaped precipitates. (c) A plan-view image shows Mn-rich phases on top of the Ge:Mn film before etching. (d) The rings of the diffraction pattern from (c) can be assigned to nearly randomly oriented Ge2Mn5. (e) The HAADF plan-view image after etching reveals the Mn-rich amorphous Ge:Mn nanonet. EDX analysis on crystalline Ge:Mn (point 1) shows no detectable Mn, whereas EDX on the nanonet (point 2) reveals more than 50% Mn. (f) The conventional TEM image of the percolated Mn-rich nanonet reveals vertices with three and four threads.
(Color online) Sheet resistance of the as implanted, pulsed laser annealed Ge:Mn and after etching away a 10 nm and a 40 nm thick surface layer. After etching away 40 nm, there is an overall increase in the sheet resistance similar to the chemically etched Ge:Mn. This indicates that the polycrystalline Mn-rich top layer and the underlying nanonet are mainly responsible for the electrical properties in PLA Ge:Mn. The inset shows the SSRM data probed on a 450 nm long section line in the center of the 10 nm etched sample.
(Color online) Hall resistance of Mn implanted Ge after PLA and after etching away 10 nm. The insets show an overview of the Hall resistance (in units of Ω) for both samples from −9 T to 9 T. A clear hysteresis at 30 K is visible for the non-etched sample, whereas 10 nm etching leads to a vanishing hysteresis at 30 K. At higher temperatures, the n-type substrate seems to influence the Hall resistance. The results indicate that the nanonet is responsible for the hysteretic anomalous Hall effect.
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