Origin of Spinel Nanocheckerboards via First Principles

TL;DR

This paper uses first-principles calculations to explain the formation of nanocheckerboards in Mn-based spinels, revealing the roles of thermodynamics, kinetics, and surface energetics in their self-organization.

Contribution

It provides a first-principles explanation for the origin of spinel nanocheckerboards, combining phase diagram analysis with surface and Jahn-Teller physics.

Findings

Total phase separation predicted at zero temperature.

Checkerboard ordering driven by surface energetics and geometry.

Kinetics and Jahn-Teller effects influence nanostructure formation.

Abstract

Self-organizing nanocheckerboards have been experimentally fabricated in Mn-based spinels, but have not yet been explained with first principles. Using density-functional-theory, we explain the phase diagram of the $\mathrm{ZnMn_xGa_{2-x}O_4}$ system and the origin of nanocheckerboards. We predict total phase separation at zero temperature, then show the combination of kinetics, thermodynamics, and Jahn-Teller physics that generates the system's observed behavior. We find the {011} surfaces are strongly-preferred energetically, which mandates checkerboard ordering by purely geometrical considerations.