Room-Temperature Ferromagnetic Ga_(1-x)Mn_xAs(x <= 0.05)Nanowires: Dependence of Electronic Structures and Magnetic Properties on Mn Content

摘要

Ga_(1-x)Mn_xAs 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 = 60nm)grown along the [111]direction.The Mn doping decreases the lattice constant,most significantly at x approx= 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 Mn~(2+)ions and the holes.X-ray absorption spectroscopy and X-ray magnetic circular dichroism confirmed that the Mn~(2+)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 approx= 0.03.