| AVS 58th Annual International Symposium and Exhibition | |
| Magnetic Interfaces and Nanostructures Division | Thursday Sessions |
| Session MI-ThM |
| Session: | Emerging Magnetic Characterization and Results |
| Presenter: | Abhijit Chinchore, Ohio University |
| Authors: | A.V. Chinchore, Ohio University K.K. Wang, Ohio University A.R. Smith, Ohio University V. Ferrari, University of Buenos Aires, Argentina A. Barral, University of Buenos Aires, Argentina |
| Correspondent: | Click to Email |
The III-V diluted magnetic semiconductors (DMS) are a new class of materials with promising applications in spintronics.[1] The low solubility of transition metal atoms into III-V semiconductor host has been a key concern in the successful development of DMS. This low solubility however was used to advantage by Lu et.al. to develop an ideal magnetic/semiconductor bi-layer [2]. Wang et.al. recently reported high density 2D Mn-Ga stripe phases on Ga-Polar GaN(0001) surface, with interesting atomic spin arrangement. [3] The N-Polar GaN(0001) 1×1 structure offers an added advantage over the Ga-Polar structure, as the Mn atoms deposited on this surface are in closer proximity to the N atoms favoring the GaMnN bonding.
We have conducted a series of experiments aimed at understanding the behavior, electronic and magnetic properties of Mn atoms on N-Polar GaN(0001) 1×1 surface. The experiments were conducted in a custom built MBE-STM system with in-situ sample transfer ability. The growth is monitored with reflection high energy electron diffraction (RHEED). The standard GaN(0001) 1×1surface was prepared and was exposed to sub monolayer doses of Mn at various temperatures. It was observed that the behavior of Mn atoms on GaN(0001) 1×1surface is highly sensitive to the substrate temperature (Ts). The low temperature Mn deposition, Ts ~ 100 °C, led to the formation of a metastable 3×3 structure which transformed to a more stable √3 × √3 R30° structure, when the sample is heated to Ts ~ 120 °C, as confirmed by RHEED. It was observed that the √3 × √3 R30° structure is stable up to 750 °C. The temperature dependent behavior of the structures suggests that the Mn atoms are physisorbed while forming the metastable structure and they are chemisorbed in the case of the stable √3 × √3 R30° structure. The STM measurements performed on the Mn 3×3 structure showing the metastable nature of the structure are presented as well are the STM and STS results showing the characteristics of √3 × √3 R30° surface. RHEED simulations confirming the surface atomic arrangement for the structure are presented. The theoretical calculations are performed using the first principles and the Tersoff-Hamann simulation method. The results indicate that the Mn atoms push the Ga atoms laterally in the surface ad-layer forming bonds directly with the bilayer N atoms. The funding from NSF and DOE for the project is greatly acknowledged.
References.
[1] T. Dietl et.al. Science 287, 1019 (2000).
[2] E. Lu et.al. Phys. Rev. Lett. 97, 46101 (2006).
[3] K. Wang et.al. Phys. Rev. B 83, 165407 (2011)