Studies On FePt Series Optical-magnetic Recording Media

Optical-magnetic hybrid recording is a novel kind of super-high density information storage method that can break through the super-paramagnetic limit and further increase the recording density as well as the writing and reading data rates of hard disk drives (HDD). It takes advantages from MO and magnetic recording methods. The message writing is by laser-assisted thermal magnetic recording and message reading is by magnetic flux detection with high sensitive GMR sensors. The study about optical-magnetic hybrid recording media is one of the key technologies for its application. In this dissertation, there are mostly tow parts studying on the FePt perpendicular recording media for hybrid recording surround the recording media and recording model.Experimentally, a series of FePt thin films were deposited by RF magnetron sputtering, and the L1₀-FePt films were obtained after the as-deposited samples were subjected to vacuum annealing. The physical properties and microstructure of both as-deposited and annealed thin films were measured. The experiment part includes the study on the perpendicular orientation of FePt single layer films and the Ag/FePt films; the research on the magnetic properties of the [Fe/Pt]_n and [FePt/Ag]₁₀ multilayer films with different structure; the effect of the different cooling rate and different annealed time on the magentic of FePt films and the effect of Ni doping on the magnetic and the Curie temperature of FePt films. The results shows that: the perpendicular orientation FePt single layer films and the Ag/FePt films have been successfully fabricated; the remanence squareness Mr/Ms of the film with the nature cooling process is bigger than that with the fast cooling process; the Fe/Pt multilayer structure can effectively reduce the ordering temperature of FePt film; Ni doping can effectively reduce the Curie temperature of FePt.Theoretically, Using micromagnetic to simulate the magnetization reversal mechanism in FePt films, and describe the distribution of magnetic moments at different steps during the magnetization reversal, and study the angular dependence of coercivity and the effect of grain size on the coercivity; Simultaneously, This part investigates the effect of grain size on the transition noise performance including transition length Cross Track Correlation Length and Position Jitter. The simulation results shows that: the micromagnetic simulation angular dependence of coercivity reveals a Stoner-Wohlfarth mode. As the grain size increases, the coercivity gradually reduces and the transition noise increases.