Thin films of Sendust (wt. 85% Fe, 10% Si, 5% Al) were deposited by rf diode and dc magnetron sputtering. The objective was the production of soft magnetic films without post deposition annealing. Films were deposited on both glass and Al2O3/TiC(AlTiC) ceramic substrate. Coercivities in the range 45 to 50 Oe for rf diode deposited and 25 to 35 Oe for dc magnetron deposited films were measured. Application of rf bias to the substrate reduced this further to 7 to 12 Oe together with a reduction in grain size. The value of magnetic flux at the surface of the sputtering target was controlled by an electromagnet and found to be an important parameter for the production of soft magnetic films, low flux densities producing the softest layers. This may be related to deposition rate and/or the influence of the target magnetic field penetrating into the substrate region. The softer magnetic layers produced as a result of applying a low rf bias to the substrate is believed to be due to ion bombardment during deposition resulting in smaller grain size. © 1998 American Institute of Physics.