Exchange bias and two steps magnetization reversal in porous Co/CoO layer

• Published in: Materials & design 2019-06, Vol.171, p.107691, Article 107691
• Main Authors: Ovejero, Jesús G., Godinho, Vanda, Lacroix, Bertrand, García, Miguel A., Hernando, Antonio, Fernández, Asunción
• Format: Article
• Language: English
• Subjects: Double loop; Exchange bias; Porous
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2019.107691

In this paper Co/CoO thick layers (hundreds of nanometers) of different porosity and oxidation degree were prepared in a magnetron sputtering deposition process by tailoring the DC sputtering power, as well as the process gas and target composition. The control of the synthesis parameters allowed the nanostructuration of the films with a singular distribution of closed pores and a controlled amount of CoO. We observed an exchange bias field of 2.8 KOe for porous Co/CoO composites, similar to Co/CoO bilayers but for coatings thicker than 300 nm. Besides, it was observed that the coating presents bistable magnetic features when cooled under zero field conditions as a result of the unusual exchange coupling. [Display omitted] •Sputtering coatings using partially oxidized Co targets and a He/Ar atmosphere creates porous composites of Co/CoO.•It is possible to create flexible magnetic layers of Co/CoO nanocomposites depositing over Kapton substrates.•Porous Co/CoO coatings can generate an exchange bias effect similar to Co/CoO bilayers but in layers thicker than 300 nm.•Controlling the composition and porosity of Co/CoO coatings it is possible to generate two-steps magnetization loops.