A material layer for a laminated core of an electric machine is made of iron-containing ferromagnetic material and includes an electrically insulating coating on at least one side of the material layer. The electrically insulating coating Includes an electrically Insulating material which Is produced through controlled oxidation of the ferromagnetic material of the material layer and contains iron monoxide and/or triiron tetraoxid. The material layer is produced from a green body, which Is sintered under a reducing atmosphere.