A magnetic disk has a soft magnetic underlayer comprising a first layer containing NiFe having a concentration of iron that is at least thirty percent and not more than seventy percent; a second layer that adjoins the first layer and contains FeCoN having a concentration of iron that is greater than the second layer's concentration of cobalt, having a concentration of nitrogen that is less than the second layer's concentration of cobalt and less than three percent; and a third layer containing FeCoNi having a concentration of nickel that is less than eight percent, having a concentration of cobalt that is less than the third layer's concentration of iron and greater than the third layer's concentration of nickel, the third layer adjoining only one of the first and second layers. The first and second layers may be repeated to form a magnetically soft high B.sub.S laminate for a disk underlayer.