Study On Co-rare Earth And Its Coupled Thin Films For Perpendicular Magnetic Recording

Hybrid recording is a new kind of high density information storage technology that can break through the super-paramagnetic limit and increase the recording density of hard disk drives (HDD). Hybrid recording is a promising candidate for future magnetic recording with areal density beyond 1Tbits/in². Hybrid recording involves not only magnetic process but also thermal and optical process, which require its media have a combination of magnetic, thermal,optical and tribological properties. This dissertation presents experimental and theoretical investigation of physical properties, micro-structure and relative mechanism of the Co-rare earth and its coupled thin films of perpendicular magnetic recording, and obtained a series of innovated conclusions and results. Experimentally, a series of thin films, such as DyCo/Cr, SmDyCo/Cr, NdTbCo/Cr, NdDyCo/Cr, were fabricated by RF magnetron sputtering technique successfully. The basic magnetic properties, optical properties and microstructure were examined. The influence of Cr underlayer to micro-structure of DyCo was researched. We have found that the Cr underlayer can enhance the coercivity and benefit the growth of DyCo perpendicular magnetic films. The effect of the different annealing methods on the magnetic properties of DyCo/Cr thin film was researched. We have found that vacuum annealing method is helpful to increase the coercivity of DyCo/Cr thin film. The effects of the light rare earth element Sm or Nd substitution on the magnetic, magneto-optical and temperature properties of DyCo, TbCo films were researched. We have found that the effect of the composition of thin films on the temperature properties of thin films is very remarkable. With the increasing of temperature, appropriate composition of thin films can keep the saturated magnetization unchanged, and the coercivity is decreased rapidly. Theoretically, the temperature dependence curves of Dy₃₁Co₆₉ thin films have been simulated and explained with mean filed theory. We have calculated that the Curie temperature and the compensation temperature of Dy₃₁Co₆₉ thin films are 670 K and 275 K. By using micro-magnetic model and micro-magnetic simulated software-SimulMag, we simulated the magnetic properties and dynamic magnetic process of SmDyCo single magnetic films and SmDyCo magnetic films with soft underlayer systemically. The simulation results were in good accord with the experimental results. The forming conditions of the interface magnetic domains and the switching behaviors of LRE-HRE -TM exchange coupled double layers under magnetic fields have been studied and the magnetic properties of LRE-HRE-TM exchange coupled double layers have been explained by using micro-magnetic model. Finally, we simulated the magnetic properties and readout properties of the anti-ferromagnetic coupled film which has a super-thin non-magnetic spacing layer. We have calculated the effects of the thickness of stabilized layer on the product of the remanent magnetization and thickness of the anti-ferromagnetic coupled film, and found that with the increasing of thickness of stabilized layer, the product of the remanent magnetization and thickness of Anti-ferromagnetic coupled film decreased.