Oxide layers with ferro- and ferrimagnetic characteristics formed on aluminum via plasma electrolytic oxidation

(Fe+Co)-containing oxide coatings are formed on aluminum alloy. It is established that at a temperature of ∼2 K, the coatings manifest ferromagnetic properties. The coatings, formed within 5 min, are characterized by an anomalously high coercive force Hc = 1300 Oe. At room temperature (300 K), they manifest ferromagnetic properties, whereas in external fields of ∼30 kOe they tend to transition into the antiferromagnetic state. It is concluded that magnetism is in this case due to the presence in the coating’s pores of crystallites ∼50–100 nm in size that consist predominantly of reduced iron, cobalt, and aluminum.