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Manganese 3×3 and √3 × √3-R30º structures and structural phase transition on w-GaN(0001̄) studied by scanning tunneling microscopy and first-principles theory

By Abhijit V. Chinchore, Arthur R. Smith and Pablo Ordejón


et al.Manganese deposited on the N-polar face of wurtzite gallium nitride [GaN (0001̄)] results in two unique surface reconstructions, depending on the deposition temperature. At lower temperature (less than 105ºC), it is found that a metastable 3×3 structure forms. Mild annealing of this Mn 3×3 structure leads to an irreversible phase transition to a different, much more stable √3×√3-R30º structure which can withstand high-temperature annealing. Scanning tunneling microscopy (STM) and reflection high-energy electron diffraction data are compared with results from first-principles theoretical calculations. Theory finds a lowest-energy model for the 3×3 structure consisting of Mn trimers bonded to the Ga adlayer atoms but not with N atoms. The lowest-energy model for the more stable √3×√3-R30º structure involves Mn atoms substituting for Ga within the Ga adlayer and thus bonding with N atoms. Tersoff-Hamman simulations of the resulting lowest-energy structural models are found to be in very good agreement with the experimental STM images.Research supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DE-FG02-06ER46317 (STM studies of nanoscale spintronic nitride systems) and by the National Science Foundation under Award No. 0730257 (advancing nanospintronics through international collaboration). V.F. and M.A.B. would like to acknowledge support from CONICET (PIP0038) and ANPCyT (PICT1857) as well as the Ohio Supercomputing Center for computer time. P.O. was supported by Spanish MICINN (FIS2009-12721-C04-01, FIS2012-37549-C05-02 and CSD2007-00050).Peer reviewe

Publisher: 'American Physical Society (APS)'
Year: 2013
DOI identifier: 10.1103/PhysRevB.87.165426
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Provided by: Digital.CSIC

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