Structural and Electronic Properties of Mn$_{x}$Ga$_{1-x }$Monolayers on Wurzite GaN(0001) Surface

Ferromagnetic (FM) metal/semiconductor bilayers are of great interest due to their importance in novel spintronics applications, such as spin injection and spin light-emitting diodes$^{[1]}$. It has been reported$^{[2]}$ that $\delta $-MnGa, a FM alloy with T$_{C}$ higher than room temperature (RT), can be grown epitaxial on top of w-GaN(0001) with sharp interface and controllable magnetism. Using molecular beam epitaxy, we deposit up to 3 monolayers (ML's) of Mn onto w-GaN(0001) ``1x1'' surface, which forms Mn$_{x}$Ga$_{1-x}$ with x varying from 0 to $\sim $ 0.6. Mn-induced surface reconstructions and formation of Mn$_{x}$Ga$_{1-x }$crystalline phases are observed by reflection high-energy electron diffraction (RHEED), Auger electron spectroscopy as well as \textit{in-situ} RT-STM. The data suggests large-period reconstructions upon deposition of $<$ 0.25ML Mn and quick formation of $\delta $-MnGa at $\sim $1 ML of Mn. Structural and electronic properties at representative stages will be presented, as well as possible magnetic properties of MnGa ML's. This work has been supported by DOE (Grant No.DE-FG02-06ER46317) and NSF (Grant No.0304314). Equipment support from ONR is also acknowledged. [1] S.A.Wolf \textit{et al}, Science \textbf{294}, 1488 (2001) [2] E.Lu \textit{et al}, Phys.Rev.Lett. \textbf{97}, 146101 (2006) K.K.Wang \textit{et al, M}ater.Res.Soc.Symp.Proc.1118-K06-06 (2009)