Physicochemical Principles Underlying the Synthesis of Granular Semiconductor–Ferromagnet Magnetic Structures Exemplified by AIIGeAs2 (AII = Zn, Cd) Materials

Abstract

This paper presents an analytical review that addresses physicochemical principles underlying the synthesis of granular structures in semiconductor–ferromagnet systems. Such systems comprise a II–IV–V₂, II₂–V₃, or II–V₂ compound as a semiconductor and MnAs as a ferromagnet. We demonstrate that granular magnetic structures are an alternative to superlattices in spintronic devices and can exhibit giant magnetoresistance and tunneling magnetoresistance effects. It is shown that, owing to the high carrier mobility in semiconductors, they are more attractive as matrices of granular materials than are metals or dielectrics. We have formulated the basic principles underlying the synthesis of granular structures with high magnetoresistance based on eutectic systems. Eutectic crystallization involves simultaneous crystallization of all the constituent phases, leading to the formation of an unusual, fine structure. High cooling rates are favorable for metastable crystallization. This causes a synergistic effect, stimulating nanostructuring and favoring the formation of granular structures. We present results on semiconductor–ferromagnet systems and demonstrate the possibility of producing granular magnetic structures with high magnetoresistance in such systems.