Experimental study of nonlinear transition shift and error rate degradation caused by thermal decay

It is demonstrated that the nonlinear transition shift (NLTS) increases wit h time in a thermally unstable medium. The measurements were performed usin g an experimental medium with low magnetic moment. The increase of NLTS dur ing thermal decay can be explained by the density dependence of the decay r ates. This density dependence of thermal decay rates is caused by demagneti zation field from adjacent transitions. A random magnetization pattern demo nstrates different amplitude decay at high and low densities, and an increa sed level of NLTS. Error rates of PRML channel were estimated before and af ter the thermal decay. (C) 1999 American Institute of Physics. [S0021-8979( 99)70908-4].