Structural and magnetic properties of Er thin films and Er/Y superlattices. II. Modification of the commensurate spin states - J.A. Borchers; M.B. Salamon; R.W. Erwin; J.J. Rhyne; G.J. Nieuwenhuys; R.R. Du; C.P. Flynn; R.S. Beach (Physical Review B, 1991)