The Study Of Heat Transfer Mechanism Of The Disk In The Laser Heat Assisted Magnetic Recording

Magnetic recording has been widely used for its high reliability and high storage density. The effective ways of enlarging the storage density are to miniaturize the recording particles or decrease the flying height. Magnetic recording becomes unstable when the particles decrease to a specific size due to the super paramagnetic limit. While the decreasing of flying height will increase the probability of the transient contact between the magnetic recording head and the hard disk, which will cause wearing and corrosion on the disk, thus decreasing the reliability and cutting down the working hours of the hard disk. Heat assisted magnetic recording(HAMR) is the most promising method to increase the storage capacity drastically. A nanoscale laser spot is used in HAMR to heat the magnetic recording layer which is made by the material with high coercivity and anisotropy to reach its curie temperature, then the recording layer is easy to be magnetized by the recording head. HAMR can raise the writing ability of high capacity in the weak magnetic field of the recording head. Besides, substantial efforts have been devoted to study the thermal issues of the TFC recording head, while the nanoscale heat transfer in the disk and the near field radiative heat exchange between the magnetic recording head and the disk are insufficient. The finite element method was used to study the heat transfer and the thermal deformation in the disk, the near field radiative heat flux of Si C was calculated. The main content of this paper includes:The Fourier model of heat transfer was developed, the hyperbolical heat transfer model was built on the micro level by utilizing the Boltzmann equation, the difference between the Fourier model and the hyperbolical model was analyzed, including the properties of the hyperbolical heat transfer model. Then the rationality of making use of the hyperbolical model to solve the heat transfer in the disk was discussed. The model concerning the characteristics of heat transfer in the disk was established on the base of the hyperbolical heat transfer model.The finite element model of the disk was built. The disk with one layer was consisted of the recording layer and the two layers disk concludes the recording layer and the base. The heat transfer in the recording layer follow ed the hyperbolical model and the heat transfer in the base obeyed the Fourier law. The heat transfer and the temperature distribution of the disk was investigated by changing the laser parameters, the recording layer parameters and the base materials, also the storage capacity was discussed. The difference of the thermal deformation between the Fourier model and the hyperbolical model was analyzed. Besides, the effects on the deformation of the base parameters were investigated.The theoretical model of the near filed radiative heat flux of Si C was built to calculate the heat flux of the semi-infinite thermal source layer and the thin thermal source layer, besides the effects of the thickness and the temperature of the thermal source layer and the width of the vacuum gap was investigated.