An active part of an electrical machine includes teeth, each having a tooth base, a tooth height, open or closed grooves between the teeth, and windings introduced into the grooves. Each winding encloses at least one of the teeth. The active part has a thickness, starting from the outer surface of the respective tooth bases and extending along the teeth, that is greater than the tooth height. The active part, starting from the respective tooth base up to a limit depth, which is not more than equal the tooth height, has a first material with a first magnetic permeability and starting from the limit depth a second material with a second magnetic permeability. The first magnetic permeability is greater than the second magnetic permeability. The limit depth is essentially half as great as the tooth height.