The FePt single layer films with different thickness were deposited by RF magnetron sputtering on glass and Corning glass substrates, and the L10-FePt films were obtained after the as-deposited samples were subjected to vacuum annealing using different cooling processes. It costs 7 hours for the temperature to decrease from 550 to the room temperature during the natural cooling process, however it just costs 1.5 hours during the fast cooling process.Results show that after annealed at for 1h, the perpendicular coercivity of the FePt single layer films decreases with the increasing of FePt layer thickness, and the FePt 15nm film exhibits a high perpendicular coercivity of 8308 Oe and a low in-plane coercivity of 5141 Oe, which suggests that the film exhibits a high perpendicular anisotropy. The FePt films with nature cooling can obtain larger Mr/Ms values than that with fast cooling.
CoCrPt/Ti/C, CoCrPt/C/Ti and CoCrPt/C/CoCrPt/Ti thin film were prepared to study the effect of thin C layer insertion on the magnetic properties and microstructure of CoCrPt/Ti hybrid recording media. Surface roughness improvement and C atoms' diffusion to Ti underlayer contribute to optimized magnetic properties in CoCrPt/Ti/C films due to C seedlayer insertion. Very thin C intermediate layer gives rise to smaller magnetic grain size and improved perpendicular coercivity in annealed CoCrPt/C/Ti thin film while thicker C intermediate layer hinders the epitaxial growth relationship between Ti underlayer and Co-alloy magnetic layer. 3nm C intermediate layer in CoCrPt/C/CoCrPt/Ti thin film structure helps to obtain smaller grain size and weaker inter-granular exchange coupling interaction in the magnetic layer after annealing process. C atoms' diffusion into Ti underlayer, Co-alloy magnetic layer or grain boundary in magnetic layer plays an important role in the effect of thin C layer insertion on the magnetic property and microstructure of CoCrPt/Ti hybrid recording media.
The authors demonstrate microwave assisted switching process of Ni80Fe20 thin film element with micromagnetics.
Effects of microwave amplitude and frequency on the magnetization reversal were focused. Numerical results showed
that the coercivity of Ni80Fe20 thin film element can be reduced by the modification of the microwave field, and the most
evident reduction of coercivity was found at resonance frequencies. Considerable Fluctuations of switching fields are
found at the natural resonance frequencies and high microwave amplitudes, which can be explained by scattering of
nucleation sites induced by the thermal effect of the microwave filed.
The (Sm,Nd)(Tb,Dy)Co thin Film had been prepared with spf-430H r.f.-magnetron sputtering system. The effects of heavy rare earth Tb, Dy substituted by light rare earth Sm, Nd on the magnetic and magneto-optical properties have been investigated. With the increasing of light rare earth Sm, Nd composition, the saturation magnetization Ms, the reflectivity R and the Kerr rotation angle θk are increased, while the coercivity (Hc) is decreased distinctly. This can be explained with the ferri-magnetic structure of RE-TM alloy. Mr/Hc Ratio is increased with the increasing of Sm composition in
SmTbCo and SmDyCo. The influence of composition and sputtering conditions on perpendicular anisotropy films are reported in detail.
Light rare earth-heavy rare earth-transition metal (LRE-HRE-TM) thin films are a kind of important recording media. A lot of researches have been carried out on the LRE-HRE-TM thin films to improve its properties for data storage application and fruitful results have been achieved. This report gives a glance on the evolution of the research on LRE-HRE-TM recording media. At the same time, combined with the hybrid recording technology, some experimental results obtained on LRE-HRE-TM recording media are discussed, which suggest the promising prospect of the LRE-HRE-TM media in hybrid recording application.
Combining the advantages of hard-disk magnetic recording and magneto-optical recording, hybrid recording is regarded as promising candidate for extremely-high density recording technology beyond Tera bits/in2. To obtain such high areal density, hybrid recording media are required to have high coercivity and large remanent magnetization at room temperature, the desired temperature dependence of coercivity and magnetization, as well as very short thermal response time. Currently, the researches on the hybrid recording media mainly involve the magnetic hard-disk polycrystalline recording media and the magneto-optical amorphous media. This report presents the latest progresses in the researches on these two kinds of media for hybrid recording.
Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.
The magnetic and magneto-optic properties of TbCo/Cr thin films were studied. A comparison of the MO properties was made between TbCo thin films with and without Cr underlayer. It was found that Cr underlayer helps to increase the Kerr rotation angle and to enhance the coercivities of TbCo thin films. The effects of the thickness of Cr underlayer and the gas pressure during Cr underlayer preparation on the magnetic and magneto-optic properties of TbCo layers were investigated, as well as the temperature dependence of these properties of TbCo/Cr thin films.
In order to meet the requirements of high saturation magnetization (Ms) and large coercivity (Hc) at room temperature for hybrid recording, the TbCo/Cr films with perpendicular anisotropy were prepared by an r.f. magnetron sputtering system without applying bias voltage. The influence of sputtering conditions and the effects of Sm substitution on the magnetic and magneto-optical properties of TbCo/Cr films were studied. It was found that although the Hc of TbCo/Cr could be optimized by choosing suitable sputtering parameters, but the partial Tb substituted by Sm will directly affect the magnitude of saturation magnetization Ms and the Kerr rotation angle 0k. This can be explained with the feeri-magnetical structure of RE-TM alloy. Under the optimized sputtering conditions, when the magnetic layer composition was (Sm0.343Tb0.657)31Co69, the Ms as high as 385emu/cm3 and the Hc as high as 4.7KOe at room temperature were obtained.