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The dedicated servo media (DSM) is the conventional perpendicular magnetic recording (PMR) media with an inserted servo recording layer between the data recording layer and the soft underlayer. By using the conventional PMR media as the reference, the design consideration on the layer structure, the preparation, the magnetic properties, the microstructure, including the $c$ -axis orientation and the growth of the layers, the surface roughness, and the recording performance for the DSM are reported.

The perpendicular magnetic recording (PMR) in hard disk drives is approaching its physical limitation. The emerging technologies, such as heat assisted magnetic recording and microwave assisted magnetic recording have been proposed to record on magnetic media with thermally stable smaller size grains at higher areal density (AD). However, in the media fabrication, achieving well-isolated small size of grains is more challenging than obtaining high ${K_{u}}$ material as recording media. Reducing the number of grains per bit is a major path for keeping AD growth of PMR in recent years. To minimize the SNR penalty at a smaller grain number per bit, pushing more on track density is the right approach. With the 2-D magnetic recording (TDMR) readers for inter-track interference cancellation, the off-track read capability is improved significantly for allowing a narrower track read. In the drive working environment, when the external vibration or other mechanical disturbance happens during the writing process, it creates more track squeeze at adjacent tracks and leaves a very narrow track at some locations of the track. When the track width is narrower than the squeeze to death width in the 747 curve, it causes hard failure in the channel. To solve the track squeeze problem, this paper proposes to add an additional magnetic recording layer in between the data recording layer and the soft underlayer of conventional PMR media. This additional recording layer is used to record servo information only. The continuous positioning error signal is able to improve the servo performance and to provide the real-time monitoring of the positioning error. When it is under bad servo conditions, the writing process can be stopped to avoid nontolerable track squeeze. The continuous servo signals are designed to be of moderate intensity at very low frequency, and its impact on data signal has been minimized. The linear density gap between the dedicated servo media and the conventional PMR media is able to be controlled within 3%. As the dedicated servo system keeps only around 100 wedges of track ID and sector ID at the data layer, the surface area saving at the data layer can break even in capacity. The dedicated servo technology together with TDMR readers is the key technology to achieve ultrahigh track density during both writing and reading processes.

Through a novel temperature measurement method, this paper studies the lubricant film property subjected to heat-assisted magnetic recording (HAMR) laser heating. The material characterization of lubricant film under HAMR ultra-fast heating rate and ultra-short heating period condition has been compared with that after conventional thermal heating. The relationship of lubricant degradation and decomposition with the heating rate and heat duration and the reaction of the lubricant with the metal used for the temperature sensor has been studied and discussed.

This paper investigates the effects of laser irradiation on hard disk lubricants of Z-Tetraol and DEPH. Through the study of different Heat Assisted Magnetic Recording (HAMR) laser effects on hard disk lubricant components including different perfluoropolyether backbones, hydroxyl end-group and cyclotriphosphazene end-group, suitable components for HAMR application are discussed.