Preparation And Properties Of L1 ₀ FePt Perpendicular Magnetic Recording Film Is Based On

The demand of large capacity of information storage device has increaseddramatically with the development of society. Magnetic recording technologyoccupies a unique place in the field of information storage, recording density ofmagnetic recording material is increasing every year. Magnetic recording unit volumeis become smaller with magnetic recording density increasing. When the size of themagnetic recording unit is small to a certain size, the magnetic properties of the unitwill be affected by the super-paramagnetic effect and cause the loss of information.Using the magnetic material with high magnetocrystalline anisotropy constant （Ku）can effectively reduce the influence of the super paramagnetic properties, andfurther improvement on magnetic recording areal density. However, the maximumanisotropy is limited by the write head fields. This is known as the "trilemma" of themagnetic recording. L1₀FePt has been considered to be promising candidates for thenext generation of ultrahigh density magnetic recording media due to their largemagnetic magnetocrystalline anisotropy （Ku7≈7×10erg/cm3）.In this article, we mainly study the preparation and properties of L1₀FePt-basedmedia for perpendicular magnetic recording. FePt film was prepared on the Si （100）substrate by magnetron sputtering method. The composition of the FePt film isstudied. The influence of rapid thermal annealing （RTA） temperature, thermalannealing time and deposition temperature of the thin film on the structure,morphology and magnetic properties of FePt film are studied. The results show thatthe RTA temperature helps FePt film transition into a hard magnetic L1₀phase. Thesample of RTA temperature700°C for1h is （001） preferred orientation and has highanisotropy. FePt films are thermal annealing different time at700°C. With theincrease of thermal annealing time, the out of plan coercivity of FePt film increases.The coercivity and rectangle ratio （M/Ms） of the samples increase with depositiontemperature.Single-crystal MgO （100） are used as a substrate, FePt films deposit at differenttemperatures with different thickness. The structure, morphology and magnetic properties of FePt film are studied. L1₀FePt film has height （001） orientation onsingle-crystal MgO （100） substrate. Samples deposit under high temperature has agreat magnetocrystalline anisotropy and high L1₀order degree. Improve thedeposition temperature can effectively increase the ordered degree L1₀phase andcrystalline of FePt film. The thickness of the L1₀FePt film has a great influence on thestructure and magnetic. L1₀FePt film order degree increases with the increase of filmthickness. Increase thickness can improve the L1₀FePt film ordered degree andcrystalline. The out of plan coercivity and the surface roughness of the L1₀FePt filmhave the same change trend.On the basis of above research, we use the L1₀FePt film as the hard magneticlayer,[FeNiPt]Nmultilayer deposition at room temperature as a soft magneticlayer,the influence of the soft magnetic thickness on structure and the magnetic ofthe composite film was studied. We find the structure of hard magnetic layer L1₀FePt is not influenced by soft magnetic multilayer. When the soft magnetic thicknessis24nm, the out of plan coercivity of the composite film is only30%of single hardmagnetic L1₀FePt. The introduction of soft magnetic layer, not only maintained theL1₀FePt order degree, namely the large magnetic anisotropy, the magnetic mediacan overcome the influence of super paramagnetic effect, but also can effectivelyreduce the coercivity of magnetic film. The L1₀FePt/[FeNiPt]Nmagnetizationswitching process is explained by magnetic domain wall assisted switch mechanism.On the other hand, we changed the content of Ni in soft magnetic layer, the effect ofNi content of soft magnetic layer was studied on magnetic composite films. The softregion with large Ms is favorable for reducing the switching field of hard region in thecomposite media.