slope change from a flat region at low field to a steep slope when the saf moves approximately 90 degrees to the applied field with the cofe safs the flat region disappears indicating changes in the magnetization direction something that broadens the free layer transition amorphous cofeb safs on the other hand retain the flat well defined flop at balance when the boron composition in the cofeb is decreased too much the alloy becomes crystalline and the flat region is no longer well defined i e crystalline cofeb behaves similar to cofe and is therefore not suitable these safs which have no well defined flop are not rigid and will move when a field is applied though the saturation fields are high amorphous cofeb b gt 9 with a thin cofe at the bottom interface to boost h sat exhibits desirable properties h sat preferably is greater than 1500 oe these safs exhibit similar mr as the ones with pinned saf having cofe at one interface is desirable for increasing h sat but introducing cofe on both the interfaces caused the disappearance of the flop region similar to that observed in an all cofe or crystalline cofeb safs fig1 is a simplified sectional view of an mram array 3.