Thermal stability investigations on laminated antiferromagnetically coupled media

The effect of the antiferromagnetic coupling strength (J), on the thermal stability factors (SF =K _uV/k _BT) obtained by different techniques is studied. For this purpose, laminated antiferromagnetically coupled (LAC) media were prepared with different values of J. The results indicated that values of SF are almost the same, when the value of J is smaller than J=0.1erg/cm ². However, for larger values of J (0.3 erg/cm ²), it is very clear that the different methods give different values of SF. It was explained that the difference in the values of SF comes mainly from the pinning of the bottom layer and the different time scales of application of the reverse field. In general, the method that uses larger time scales gave larger values of stability factor. The studies also indicate a possibility that the stability factors obtained from Sharrock's equation may not be accurate for LAC media with very high values of J.