Diffusion, Clustering, and Magnetic Properties of Mn dopants on a 2x2-T4 GaN(0001) Substrate...

Based on extensive rst-principles calculations with density-functional theory (DFT), we propose
a growth model of Mn on reconstructed 22-T4 GaN(0001), characterized by substitution of Ga by a
Mn adatom via a surface site T4. At lower Mn concentration, Mn dopants distribute in Ga sublattice
randomly forming intrinsic DMS. At higher concentration, planar ferromagnetic clusters oriented
in (0001) plane are easily formed at lower temperature, but ferrimagnetic zigzag columns along the
growth orientation will be formed at higher temperature. Based on these ndings, we qualitatively
explain the puzzling experimental observations on TC variations, as well as the dierent magnetic
natures in Ga1����xMnxN systems.