Unstable Playback Response of CPP-GMR Read Head Induced by Electromagnetic Interference: Structural Dependence

摘要

Although several studies have claimed that the current perpendicular-to-the-plane giant magnetoresistance (CPP-GMR) technology is the most attractive technology to achieve ultrahigh capacities of data storage applications, there are still recent studies indicating the inaccuracy of the reading head response caused by the electromagnetic interference (EMI). To improve the precision of the head response, we report a dependence of the physical dimension of CPP-GMR read head on the readback signal distortion due to the EMI. The simulations were based on micromagnetic modeling. The EMI impacts on the head response were analyzed as a function of structural parameters of the head, including the length of stripe height (SH) and read width (RW). Then, the readback characteristics of the head, including the spin-transfer induced noise, power spectral density, and bit-error-rate (BER), were discussed. It was found that an alternation of either SH or RW influences the noise profile. Adjusting the length of RW demonstrates a more influential impact on the noise than that of SH. The frequency spectrum of the head response was also carried out. The physical explanations regarding the results found in this article were given through the behavior of the demagnetization field. The effects of bias current on the head output were additionally investigated. Moreover, the BER of the head with varying the head dimensions was characterized. From findings, the appropriate sizing of the CPP-GMR sensors for an areal density of 1 Tb/in^{2 was predicted. The results can be utilized to design CPP-GMR read heads at ultrahigh areal densities.}