No abstract

Several studies have confirmed that current-perpendicular-to-the-plane giant magnetoresistance (CPP-GMR) technology is appropriate for next-generation read sensors for ultrahigh areal densities (ADs) of data storage applications. Since the physical dimension of the read sensor is a crucial factor for developing the reader to overcome its limitations, this paper proposes an optimal sizing prediction of the CPP-GMR read heads for ADs of 1-4 Tb/in 2 . Micromagnetic modelling was performed in the simulations. The appropriate length of the stripe height (SH) and the read width (RW) of the readers was estimated based on a consideration of sensor outputs including the readback signal, asymmetry parameter, dibit response and power spectral density (PSD) profile. It was found that a variation of SH and RW lengths had an influential impact on the readback signal waveform. Those affectations were further characterized through the echoes of dibit response showing that shortening the SH length or increasing the RW length could improve the resolution and reduce the distortion occurring in the readback signal. Moreover, the PSD profile indicated that the reader operation became more stable at shorter SH lengths or longer RW lengths. The head response spectrum was also examined. In addition, the magnitude of the bias current was studied in relation to the head response. Lastly, the optimal physical dimension (SH×RW) of the CPP-GMR readers for ADs of 1-4 Tb/in 2 was predicted to be (40×48) nm, (28×29) nm, (25×26) nm and (19×20) nm, respectively. The results can be utilized to design the CPP-GMR sensors at ultrahigh magnetic recording capacities.INDEX TERMS Magnetic recording, Magnetic read heads, Current perpendicular-to-the-plane giant magnetoresistance, Heusler alloys.

Recently, heat-assisted magnetic recording (HAMR) has been demonstrated to extend the areal density growth over the superparamagnetic limited. One key component of this technology is a heat sink layer in HAMR media, which benefits the thermal gradient and transition noise. However, the disadvantage of the heat sink layer (HS) has not been fully explored. In this paper, we investigate the background interference (BGI) impact as a result of the heat sink layer via the spin-stand tester. HAMR heads included a light delivery system that have measured a signal-to-noise ratio and down-track thermal gradient on a variety of HS thickness. Subsequently, we found that a thicker HS is a trade-off between the BGI and thermal gradient. Thus, it remains challenging to achieve an ultra-high areal density using the thermal media design.

This paper discusses the impact of background interference on a recorded pattern for heat-assisted magnetic recording technology (HAMR). Several patterns of the background track were examined, with the log bit error rate and signal to noise ratio measured via a spin-stand tester using HAMR head and media. It was found that the low frequency pattern gave the highest BER and SNR loss due to the strong magnetic field from the adjacent tracks. Similar to its practical use, the PRBS pattern also showed high interference. These observations may be used to support HDD areal density growth.