Room-Temperature Ferromagnetic Ga1−x Mn x As (x ≤ 0.05) Nanowires: Dependence of Electronic Structures and Magnetic Properties on Mn Content

• Published in: Chemistry of materials 2009-03, Vol.21 (6), p.1137-1143
• Main Authors: Kim, Han Sung, Cho, Yong Jae, Kong, Kang Jun, Kim, Chang Hyun, Chung, Gyeong Bok, Park, Jeunghee, Kim, Jae-Young, Yoon, Jungbum, Jung, Myung-Hwa, Jo, Younghun, Kim, Bongsoo, Ahn, Jae-Pyoung
• Format: Article
• Language: English
• Subjects: Magnetic Materials; Nanomaterials (Nanops, Nanotubes, etc.); Semiconductors
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm8033388

Ga1−x Mn x As nanowires were synthesized with finely controlled Mn contents (x = 0, 0.01, 0.02, 0.03, and 0.05) by the vapor transport method. They consisted of single-crystalline GaAs nanocrystals (avg. diameter = 60 nm) grown along the [111] direction. The Mn doping decreases the lattice constant, most significantly at x ≈ 0.03. X-ray photoelectron spectroscopy revealed that as the Mn content increases, the binding energy of Ga 2p shifts to a higher energy, which can be correlated with the hybridization between the Mn2+ ions and the holes. X-ray absorption spectroscopy and X-ray magnetic circular dichroism confirmed that the Mn2+ ions substitute into the tetrahedrally coordinated Ga sites and that the magnetic moment is maximized at x = 0.03, where the lattice constant is minimized and the binding energy of Ga 2p is maximized. The magnetization measurement revealed that all of these nanowires exhibited room-temperature ferromagnetic behavior, which is also observed most significantly for x ≈ 0.03.