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• The correlation analysis method is proposed to verify the MAS effect in the recording process. • It is confirmed that the medium-dependent gain corresponds to the FMR frequency change between the media. • This is the world's first report on the quantification of the MAS effect in the recording process. Frequency matching is the most important key point for designing microwave-assisted switching (MAS) and microwave-assisted magnetic recording (MAMR). It is necessary to quantitatively compare an assist effect by MAS (MAS effect) of some media when designing and optimizing a medium from the viewpoint of frequency matching experimentally. However, it is difficult to directly compare the MAS effect between media because the differences in the resolution and saturation characteristics of the medium strongly influence the recording properties. In this study, we propose a new method for appropriately removing these effects other than the MAS effect by evaluating the relationship of recording characteristics between media. By using this method, the difference of the MAS effect between any media can be quantitatively compared and used as an index for medium design to optimize MAMR. [ABSTRACT FROM AUTHOR]

Hard Disk Drive read heads moved from GMR to Tunneling Magnetoresistive (TMR) Devices as a way to enhance head SNR in order to keep up with advanced linear densities. TMR technology was further extended by the transition from amorphous alumina tunneling barriers to crystalline MgO barriers lattice matched to adjacent BCC magnetic layers resulting in much higher MR ratios. Enhanced side shielding using Junction Shield and reduced shield to shield spacing were additional enablers that increased track and linear density capabilities of TMR heads. TMR heads gained additional momentum and complexity by the introduction of two dimensional recording heads that boosted head SNR by up to 3 dB. As the RA of the tunneling barriers is reduced, overcoming spin torque noise presents itself as a further challenge to be addressed. As device dimensions are scaled down, magnetic thermal noise can only be overcome by increasing the moment of the free layer which may already start establishing the final density point achievable by TMR heads. [ABSTRACT FROM AUTHOR]