| AVS 57th International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Tuesday Sessions |
| Session MI+EM-TuA |
| Session: | Spintronics |
| Presenter: | K. Wang, Ohio University Nanoscale and Quantum Phenomena Institute |
| Authors: | K. Wang, Ohio University Nanoscale and Quantum Phenomena Institute A.V. Chinchore, Ohio University Nanoscale and Quantum Phenomena Institute M. Shi, Ohio University Nanoscale and Quantum Phenomena Institute A.R. Smith, Ohio University Nanoscale and Quantum Phenomena Institute |
| Correspondent: | Click to Email |
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 shown[2] that δ-MnGa, a FM alloy with TC higher than room temperature (RT), can be grown epitaxial on top of w-GaN(0001) with sharp interface and controllable magnetism. Here we report detailed studies on the formation of the first few MnGa monolayers formed by depositing up to 3 monolayers (ML’s) of Mn onto w-GaN(0001) “1x1” surface at elevated substrate temperature. Mn-induced surface reconstructions and formation of smooth MnxGa1-x crystalline monolayer films are observed by reflection high-energy electron diffraction (RHEED), Auger electron spectroscopy as well as in-situ RT-scanning tunneling microscopy (RT-STM). RHEED data showed well-ordered surface reconstructions exhibiting mainly 1/3rd and 2/3rd order streaks along [1-100] directions at lower than around 0.5 ML of Mn coverage, while two different sets of reconstruction streaks could be identified depending upon the Mn coverage. Two different types of atomic row-like features both running along close-packing direction of GaN, but having different row-row spacings, are observed with STM at room temperature. The unit-cells derived are consistent with RHEED observation. At higher than around 0.5 ML, atomically smooth MnGa layers start to cover up the surface as shown by both RHEED and STM; the epitaxial relationship is derived as d-MnGa[011]//GaN[0001] and d-MnGa[001]//GaN[11-20]. 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. 0730257). Equipment support from ONR is also acknowledged.
[1] S.A. Wolf et al, Science 294, 1488 (2001).
[2] E. Lu et al, Phys. Rev. Lett. 97, 146101 (2006); K.K. Wang et al, Mater. Res. Soc. Symp. Proc. 1118-K06-06 (2009).