Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 11: Nanostructures at Surfaces I

O 11.5: Vortrag

Montag, 31. März 2014, 11:30–11:45, WIL C107

Structure and Self-assembly of Two-dimensional Manganese Gallium Quantum Height Islands and One-dimensional Atomic Chains on Wurtzite GaN (0001) — •Jeongihm Pak, Meng Shi, Andrada-Oana Mandru, Abhijit Chinchore, and Arthur Smith — Nanoscale and Quantum Phenomena Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 USA

We describe the spontaneous formation of five and six-monolayer quantum height manganese gallium islands and atomic chains on gallium-rich, nitrogen polar GaN(0001). From ex-situ MOKE measurements at room temperature, we expect these MnGa islands to be ferromagnetic. The structural evolution is followed from the beginning of growth using reflection high energy electron diffraction, in which a dotted 2x pattern is observed to form. In-situ scanning tunneling microscopy is also used to investigate the islands* structures with atomic resolution. Based on all the observations, we propose possible bulk and surface models for the islands. A possible bonding structure at the substrate/island interface is also discussed in which Mn atoms substitute for Ga atoms within the Ga adlayer thus bonding with nitrogen, making the MnGa islands bonded directly to the last GaN bilayer. The atomic chain model on the six-layer island surface is also discussed. STM observations of atomic-chain interconnection on the six-layer island surface indicate a dynamic system at room temperature. The models presented here should serve as useful starting points for theoretical calculations.