Quantitative research into the influence of slider-disk contact force on the information intensity of the magnetic recording layer

Abstract

In order to achieve the requirement of rapid growth of the magnetic storage density, the slider-disk spacing needs to be reduced to less than 2 nm. However, the slider-disk contact can easily occur within such a narrow spacing, and eventually result in the loss of the stored data in the magnetic recording film, i.e., demagnetization of the magnetic disk. Therefore, research into the magnetomechanical relationship related to the slider-disk contact demagnetization is significantly important to identify the demagnetization mechanism and further improve the anti-demagnetization performance of the magnetic disk. In this study, the nanoscratch experiment and the magnetic force microscope technology are used to investigate the magnetomechanical behavior induced by the slider-disk contact. And according to the phase imaging principle of the magnetic force microscope, the relationship between the information intensity of the magnetic recording layer and the magnetic contrast measured by the magnetic force microscope is found. Thus, a quantitative analysis method is proposed, which is different from the previous qualitative observation of the magnetic domain change. Experimental results show that the critical demagnetization load during the slider-disk contact is 120 up N. When the slider-disk contact force exceeds the critical demagnetization load, the increase of slider-disk contact force can lead to the decrease of the information intensity of the magnetic recording layer. And the decay rate of the information intensity will be rapidly enhanced after the slider-disk contact force reaches 380 up N. Moreover, the variation trend of the information intensity with the depth of the residual scratch is the same as that of the information intensity with the slider-disk contact force. Specially, before the slider penetrates the hard carbon layer of the magnetic disk, the slider-disk contact demagnetization still may occur, corresponding to the load cases from 120 up N to 200 up N. In addition, for any slider-disk contact force, the area of the surface damage of the hard carbon layer is always greater than that of the demagnetization of the magnetic recording layer. This phenomenon is related to the elasto-plastic force fields in the hard carbon layer and the magnetic recording layer. Moreover, when the slider repeatedly scratches the same location on the surface of the magnetic disk, the information intensity of the magnetic recording layer will decrease with the increase of scratching number. After the scratching number is beyond 20, the elastic shakedown status may occur in the magnetic recording layer, and correspondingly, the information intensity of the magnetic recording layer can be close to a constant value. This result is derived from the work hardening process during the slider-disk repeatedly scratching.