Phase decomposition diagram of magnetic alloy semiconductor

Abstract

We investigate the thermodynamics of phase decomposition in magnetic alloy semiconductors (MASs) using the statistical Flory–Huggins lattice model. Based on this model, we propose a method to determine experimentally the interaction parameter χ and apply it to draw the phase decomposition diagram of (GaMn)As. The interaction energy of (GaMn)As was estimated to be about 5.7 mRy, which is close to the first principle calculation of 4.2 mRy. Using this phase diagram, we fabricated MnAs nanoparticles with a rectangular lattice structure utilizing the spinodal decomposition. We discuss the formation of rectangular and triangular lattice structures at the late stage of spinodal decomposition in MASs using the Ginzburg–Landaulike free energy function.