Interface-driven phase separation in multifunctional materials: the case of GeMn ferromagnetic semiconductor

TL;DR

This paper investigates how interfaces influence phase separation in GeMn ferromagnetic semiconductors using first-principles simulations, proposing a new class of alpha phases to explain observed coherent precipitates.

Contribution

It introduces the concept of alpha phases and demonstrates their role in phase separation, combining theoretical and experimental insights.

Findings

Interfaces significantly influence phase separation mechanisms.

Alpha phases are a key to understanding coherent precipitates.

Theoretical and experimental evidence support the existence of alpha phases.

Abstract

We use extensive first principle simulations to show the major role played by interfaces in the mechanism of phase separation observed in semiconductor multifunctional materials. We make an analogy with the precipitation sequence observed in over-saturated AlCu alloys, and replace the Guinier-Preston zones in this new context. A new class of materials, the $\alpha$ phases, is proposed to understand the formation of the coherent precipitates observed in the GeMn system. The interplay between formation and interface energies is analyzed for these phases and for the structures usually considered in the literature. The existence of the alpha phases is assessed with both theoretical and experimental arguments.