Nondestructive readout in nonplanar magnetic films

In memory applications the desire to increase speed by eliminating the rewrite cycle has intensified the interest in nondestructive readout (NDRO) operation. This paper is concerned with grooved structures considering the effect of grooves parallel to the easy axis in relaxing the limitations imposed by skew and angular dispersion upon the allowable word field. The reasons for the improved NDRO threshold are discussed on the basis of a quasi-static model assuming uniform magnetizations in the thick and in the thin regions of the film with a springlike exchange coupling. loops and NDRO thresholds are calculated and compared with experimental evidence. Landau-Lifshitz equation is applied to the same two-magnetizations model to calculate voltage waveforms of the output signal. Calculated peaks are shown to be larger than for an ungrooved film operating under NDRO limitations. The results of inductive pulse measurements indicate a similar improvement.