Ferromagnetic Mn-Doped GaN Nanowires for Nanospintronics
- PDF / 627,040 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 24 Downloads / 244 Views
S6.16.1
Ferromagnetic Mn-Doped GaN Nanowires for Nanospintronics Doo Suk Han, Chan Woong Na, Woo Sung Jang, Seung Yong Bae, and Jeunghee Parka) Department of Chemistry, Korea University, Jochiwon 339-700 Korea; ABSTRACT We report Mn-doped GaN nanowires exhibiting ferromagnetism even at room temperature. The growth of single-crystalline wurtzite structured GaN nanowires doped homogeneously with about 5 atomic % Mn was achieved by chemical vapor deposition using the reaction of Ga/GaN/MnCl2 with NH3. The ferromagnetic hysteresis at 5 and 300 K and the temperaturedependent magnetization curves suggest the Curie temperature around 300 K. Negative magnetoresistance of individual nanowires was observed at the temperatures below 100 K. INTODUCTION Diluted magnetic semiconductors (DMS) have attracted considerable research activities because of their great potential as key materials for spintronic devices.1-7 The demonstration of unique phenomena such as field-effect control of ferromagnetism, efficient spin injection to produce circularly polarized light, and spin-dependent resonant tunneling, opens a rich and various landscape for technological innovation in magnetoelectronics.1-4 Using the theory based on bound magnetic polaron model, Curie temperatures (TC) have been calculated for various 5% Mn-doped p-type III-V and II-VI semiconductors.5 The (Ga,M)N materials have been extensively studied since they are predicted to be ferromagnetic with a TC above room temperature. However, many reported experimental values are quite different and even contradictory. Near or above room temperature ferromagnetism was found by a number of groups,8-15 while no ferromagnetism or a very low TC was also reported.16,17 These studies have actually focused on the bulk materials, but the integration of DMS materials into electronics will need very low dimensions in order to make real use of the advantages offered by the spins. There is a tremendous current interest in the 1-dimensional (1D) semiconductor nanostructures as welldefined building blocks to fabricate nanoscale electronic and optoelectronic devices. Therefore the 1D DMS nanomaterials would not only be important for the applications in nanoscale spintronic devices, but also provide the fundamental ideas for the role of dimensionality and size in the magnetic related properties. Recently, Rao group reported the ferromagnetic behaviors at room temperature for the GaMnN nanowires with 1-5% Mn.18 In this paper we synthesized exclusively high-purity 5% Mn-doped GaN nanowires exhibiting room-temperature ferromagnetism by chemical vapor deposition (CVD), and measured the temperature-dependent magnetotransport properties of individual nanowires for the first time. The change of structural and magnetic properties of GaN nanowires caused by the efficient Mn doping has been thoroughly investigated. EXPERIMENTAL DETAILS Ga (99.999%, Aldrich)/GaN (99.99+%, Aldrich)/MnCl2 (99.99%, Aldrich) mixture was placed in a quartz boat loaded inside a 2.5 cm diameter and 80 cm long quartz tube reactor. The
Data Loading...
