Phase Control of Single-Crystalline Cobalt Oxide Thin Films Grown by Pulsed Laser Deposition

Functional oxides are highly fascinating materials driving much research in chemistry, physics, and materials science. In this study, we have epitaxially grown CoO and Co 3 O 4 thin films on SrTiO 3 (001) and MgO(001) substrates by pulsed laser deposition. By choosing the right deposition parameters such as substrate temperature and oxygen partial pressure, we are able to control the oxide phase and therefore the oxidation state of the transition metal controlling its physical properties. Structural analysis revealed a cube-on-cube orientation for both oxide phases with respect to the substrates and confirmed that all grown films are single-phase and single-crystalline. In addition, post-annealing in oxygen atmosphere allows to change the cobalt oxide phase from CoO to Co 3 O 4 . Furthermore, magnetic measurements indicated a Néel temperature of about 45 K for Co 3 O 4 thin films which is close to the reported bulk value. • Single-crystalline and single-phase CoO and Co 3 O 4 thin films. • Growth of thin cobalt oxide films with thicknesses between 4 and 71 nm. • Control of cobalt oxide phase by changing temperature or oxygen partial pressure. • Néel temperature of around 45 K for films grown on STO(001).