Selective growth of straight and zigzagged Ga_1-xMn_xv (0 ≤ x ≤ 0.05) nanowires and dependence of their electronic structure and magnetization on the Mn content

Straight and zigzagged Ga_1-xMn_xN (0 ≤ x ≤ 0.05) nanowires were selectively synthesized by the vapor transport method, using different growth temperature. They consisted of single-crystalline wurtzite GaN nanocrystals grown along the [1010] and [0001] directions for the straight and zigzagged morphologies, respectively. The lattice constant, c, decreases initially with increasing amount of Mn doping (x), and then increases as x increases above 0.03. X-ray photoelectron spectroscopy revealed that as the Mn content increases to x = 0.02, the binding energy of Ga 2p shifts to a higher energy, suggesting the possibility of hybridization between the Mn²⁺ ions and host defects. X-ray absorption spectroscopy and X-ray magnetic circular dichroism confirmed that the Mn²⁺ ions substitute into the tetrahedrally coordinated sites. The magnetization measurement revealed that all of these nanowires exhibited room-temperature ferromagnetic behaviors, most significantly for the straight nanowires grown with the [1010] direction, having x = 0.02-0.03.