Contact stress-induced micromagnetic behavior in magnetic recording disk

Stress plays an important role in the magnetic properties of ferromagnetic materials. Sliding contact in hard disk drives can lead to tribological failures of the disk in terms of data loss and demagnetization. However, the relationship between contact stress-induced magnetization changes and tribological failures of magnetic recording disk is rarely discussed. In this study, the contact stressinduced micromagnetic behavior in magnetic recording disk was investigated using micromagnetic simulation. A micromagnetic model including the magnetostriction effect into the Landau-Lifshitz-Gilbert equation was developed to simulate the stress effect on the magnetization changes. Then finite element analysis was used to calculate the critical stresses for the occurrence of data loss and demagnetization of perpendicular magnetic recording disk under sliding contact according to our previous experimental results. Based on these simulation results, it was found that the magnetic moment decreased by 8.9 % under the critical stress for data loss, and it rotated 55.7° under the critical stress for demagnetization. In addition, the simulated static domain structures when data loss and demagnetization occur were in agreement with the previously reported experimental results. Finally, the relationship between the contact stress-induced tribological failures and micromagnetic behavior of the magnetic disk was illustrated. It was proposed that data loss is caused by the magnetization reduction, while demagnetization is caused by the magnetization rotation.