Theoretical approach for determining the relation between the morphology and surface magnetism of Co3O4

Highlights: • A facile approach combining Wulff theorem and spin analysis have been proposed. • Ferromagnetic (1 0 0) and (1 1 1) surfaces are mandatory for Co₃O₄ morphologies. • Higher superficial magnetization were obtained tuning the E_surf for (1 1 1) plane. • Magnetic properties of solid-state materials can be associated with its morphology. Precisely controlling the different aspects of the morphology and magnetic properties of metal oxides are fundamental to materials design. A theoretical approach, based on the Wulff construction and magnetization density (M) index, is presented to clarify the relation between the morphology and surface magnetism. The M index allows us to evaluate the uncompensated spins at the (1 0 0), (1 1 0), (1 1 1) and (1 1 2) surfaces of Co₃O₄ with a spinel structure. The investigated morphologies show an excellent agreement with the experimental results, with the main contribution coming from the (1 0 0) and (1 1 1) magnetic planes. The present results are also helpful in clarifying the intriguing magnetic properties reported for Co₃O₄ nanoparticles, suggesting that the same technique may serve as a guide for the study of shape-oriented magnetic materials.