Phase transformations in the Mn-Ge system and in Ge x Mn1 − x diluted semiconductors

Abstract

Results of an X-ray diffraction study as well as magnetic and electrical measurements of the solid-state reactions in Ge/Mn polycrystalline films of an 80/20 atomic composition have been presented. It has been shown that the ferromagnetic Mn5Ge3 phase is formed first on the Ge/Mn interface after annealing at ∼120°C. The further increase in the annealing temperature to 300°C leads to the beginning of the synthesis of the Mn11Ge8 phase, which becomes dominating at 400°C. The existence of new structural transitions in the Mn-Ge system in the region of ∼120 and ∼300°C has been predicted on the basis of the presented results and results obtained earlier when studying solid-state reactions in different film structures. The supposition about the general chemical mechanisms of the synthesis of the Mn5Ge3 and Mn11Ge8 phases during the solid-state reactions in the Ge/Mn films of the 80/20 atomic composition and the phase separation in GexMn1 − x (x > 0.95) diluted semiconductors has been substantiated.