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Spontaneous shape transition of Mn x Ge 1− x islands to long nanowires

Abstract : We report experimental evidence for a spontaneous shape transition, from regular islands to elongated nanowires, upon high-temperature annealing of a thin Mn wetting layer evaporated on Ge(111). We demonstrate that 4.5 monolayers is the critical thickness of the Mn layer, governing the shape transition to wires. A small change around this value modulates the geometry of the nanostructures. The Mn–Ge alloy nanowires are single-crystalline structures with homogeneous composition and uniform width along their length. The shape evolution towards nanowires occurs for islands with a mean size of ≃170 nm. The wires, up to ≃1.1 μm long, asymptotically tend to ≃80 nm of width. We found that tuning the annealing process allows one to extend the wire length up to ≃1.5 μm with a minor rise of the lateral size to ≃100 nm. The elongation process of the nanostructures is in agreement with a strain-driven shape transition mechanism proposed in the literature for other heteroepitaxial systems. Our study gives experimental evidence for the spontaneous formation of spatially uniform and compositionally homogeneous Mn-rich GeMn nanowires on Ge(111). The reliable and simple synthesis approach allows one to exploit the room-temperature ferromagnetic properties of the Mn–Ge alloy to design and fabricate novel nanodevices.
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Contributor : Isabelle Berbezier Connect in order to contact the contributor
Submitted on : Thursday, March 10, 2022 - 4:08:15 PM
Last modification on : Friday, April 1, 2022 - 3:54:54 AM

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S Javad Rezvani, Luc Favre, Gabriele Giuli, Yiming Wubulikasimu, Isabelle Berbezier, et al.. Spontaneous shape transition of Mn x Ge 1− x islands to long nanowires. Beilstein Journal of Nanotechnology, Karlsruhe Institute of Technology., 2021, 12, pp.366-374. ⟨10.3762/bjnano.12.30⟩. ⟨hal-03604811⟩



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