The effects of different demagnetisation processes on interaction effects in thin film media

The effects of different erasure processes (AC and DC cyclic erasure (DCE)) have been examined for CoNiCr films with various Cr underlayer thicknesses. The erased states after AC and DC processes for very small field increments were found to be macroscopically similar, indicating that the state produced is likely to correspond to the magnetic ground state of the system. The difference between the AC and DCE techniques is that for the AC case at each step of field reduction the sample is cycled through a minor loop at 50 Hz where in the DCE case only one cycle is applied. The effect of rapid demagnetization was found to result in nonequilibrium magnetic configurations. The erased state in these films was found to be anisotropic, thus measurements should be made in the same direction as erasure in order to obtain the true interaction behavior. It is concluded that, when interaction effects are examined via the δI technique, demagnetization processes which produce the lower energy magnetic configurations must be used