Modification of the local atomic structure around Mn atoms in (Ga, Mn)As layers by high temperature annealing

• Published in: Journal of physics. Condensed matter 2007-12, Vol.19 (49), p.496205-496205 (14)
• Main Authors: Demchenko, I N, Lawniczak-Jablonska, K, Story, T, Osinniy, V, Jakiela, R, Domagala, J Z, Sadowski, J, Klepka, M, Wolska, A, Chernyshova, M
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Inorganic compounds; Magnetic properties and materials; Magnetic semiconductors; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Studies of specific magnetic materials
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/19/49/496205

Changes of the local structure around Mn atoms in (Ga, Mn)As layers after high temperature annealing were determined by x-ray absorption spectroscopy (EXAFS) and high-resolution x-ray diffraction (HRXRD) measurements, and related to their magnetic properties. X-ray absorption is known to be able to detect crystalline structure changes occurring around investigated atoms. The qualitative and quantitative analysis of EXAFS spectra gives unambiguous evidence for the transition from a cubic to a hexagonal phase around Mn atoms as a result of annealing at temperatures of 500 and 600 deg C. The performed HRXRD investigation indicated a relaxation of the GaAs matrix during annealing, from highly to slightly compressively strained, and finally, after the formation of inclusions of hexagonal MnAs, to slightly tensile strained. The sample with hexagonal MnAs inclusions exhibits ferromagnetic properties up to room temperature with almost all Mn atoms being in a ferromagnetic phase.