A magnetron sputtering target assembly, comprises a target adapted to comprise of at least one material to be sputtered, the target including a pair of oppositely facing surfaces; and a magnet assembly comprising a plurality of Halbach magnet arrays adjacent one of the surfaces for providing magnetic field lines which emerge from and re-enter the other of the surfaces to form an arched, closed-loop magnetic field path over the other surface. The enhanced magnetic flux intensity provided by the Halbach magnet assemblies, relative to conventional magnetron magnet assemblies, facilitates sputtering of thick targets comprised of magnetic materials in the manufacture of recording media, as well as low pressure sputtering of high quality carbon-containing protective overcoat materials for such media.