Seed-layer effect on the microstructure and magnetic properties of Co/Pd multilayers (original) (raw)
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The Effects of the Pd-TiN Seed Layer on the Magnetic Properties of Co/Pd Multilayered Media
IEEE Transactions on Magnetics, 2000
We investigated a Pd-TiN thin film as a seed layer for a [Co/Pd] multilayered perpendicular magnetic recording media. The 15-nm Pd-TiN thin film and [Co(0.2 nm)/Pd(0.8 nm)] multilayered media were fabricated by dc magnetron sputtering without heating the substrate. The Pd-TiN(20 vol.%) granular seed layer with apparent grain boundaries is considered to provide suitable seeds to [Co/Pd] multilayer and reduced the magnetic exchange coupling of [Co/Pd] grains causing an increase of the perpendicular coercive field and a decrease of the magnetic cluster size for the [Co/Pd] multilayered media. These results suggest that the Pd-TiN seed layer contributed to the formation of physically well-separated [Co/Pd] multilayered grains, improving the magnetic properties of [Co/Pd] multilayered media.
Journal of Applied Physics, 2003
In this work, we investigate the postannealing effects on the magnetic and structural properties of CoCrPt perpendicular films. We observe a coercivity of 5000 Oe in the films with a 2 nm CrMn overlayer, which is about two times larger than the coercivity of similar films without a CrMn overlayer. This increment is attributed to the decoupling of grains by diffusion of CrMn from the top layer through the grain boundaries. An increase in the negative nucleation field and a decrease in intergranular exchange coupling with annealing temperatures was observed for the films with a CrMn overlayer. On the other hand, the films without a CrMn overlayer show the opposite trends except at high annealing temperature ͑450°C͒. We observe a coercivity of ϳ7600 Oe and a negative nucleation field of ϳ2400 Oe for a film with a CrMn overlayer annealed at 450°C for 5 min.
Development of CoX/Pd multilayer perpendicular magnetic recording media with granular seed layers
Journal of Magnetism and Magnetic Materials, 2002
CoCrRu-based granular seed layers are studied to control the hysteresis properties of CoX/Pd multilayer based perpendicular magnetic recording media. Proper choice of the CoCrRu growth conditions is found to reduce the hysteresis slope parameter a and to improve the switching field distribution, suggesting that this granular seed layer is effective in producing exchange decoupled columnar structures. The results are confirmed by magnetic force microscopy studies of recorded patterns as well as by DC/AC-erase noise measurements, remanent coercivity studies and microstructural observations by transmission electron microscopy.
Textured Growth of CoFe for Soft Underlayers In CoCrPt: SiO2 Perpendicular Magnetic Recording Media
Journal of Magnetism and …, 2006
CoFe alloy thin films were studied with the intention of potential use as a soft underlayer (SUL) for Co-based perpendicular recording media. The effect of composition and the effects of seedlayers on the formation of crystalline phase and crystallographic texture and the magnetic properties were investigated. Films deposited on Ta/Pd seedlayer were found to have a good FCC(1 1 1) texture than those deposited on glass substrates or on Ta seedlayers. The magnetic properties were also better when deposited on Ta/Pd seedlayers. On these seedlayers, Fe concentration of 15 at% was found to be suitable for the formation of FCC phase. Disks were prepared with CoFe SULs. The noise of CoFe SUL is one of the challenges to be solved. (C) 2006 Elsevier B.V. All rights reserved.
Thickness dependent magnetization dynamics of perpendicular anisotropy Co/Pd multilayer films
Journal of Magnetism and Magnetic Materials, 2011
We present the measurements of the picosecond magnetization dynamics of Co/Pd multilayer films. The dynamic magnetization properties of sputtered multilayer films were analyzed as a function of Co layer thicknesses and applied bias field. Both the eigenfrequencies of the magnetization precession in the multilayers and the associated Gilbert damping exhibit extreme sensitivity to the magnetic layer thickness on an atomic monolayer scale. The eigenfrequency increases more than threefold when the Co thickness decreases from 7.5 to 2.8Å, mainly due to the changes in effective saturation magnetization and perpendicular anisotropy constant. A concomitant 2.6-fold increase in the damping of the oscillations is observed and attributed to stronger interface dissipation in thinner Co layers. In addition, we introduce a quasi-1D micromagnetic model in which the multilayer stack is described as a onedimensional chain of macrospins that represent each Co layer. This model yields excellent agreement with the observed resonance frequencies without any free parameters, while being much simpler and faster than full 3D micromagnetic modeling.
IEEE Transactions on Magnetics, 2004
The effects of cross-sectional modulated boron segregation on Co/PdB multilayer perpendicular magnetic recording media have been studied. Gradually reduced boron contents from thin PdB seed layer (33 at.%) to the top of the Co(0.2 nm)/PdB (0.8-nm) multilayer (12.5 at.% at the center of the multilayer) were successively achieved and confirmed by the depth-profile of X-ray photoelectron spectroscopy (XPS). Observed magnetic properties and magnetic force microscopy images suggested that this gradient diffusion supports reduction of intergrain exchange coupling and improvement of the magnetic properties. The signal-to-noise ratio over 22 dB was obtained at 450 kFCI in playback tests, in combination with amorphous cobalt boron soft-magnetic underlayer (SUL). It is suggested that these properties are brought by a combination of the dispersed nucleation sites with rich boron content in the initial layer and decreasing boron content during the growth of the multilayer. In addition, this simple medium, which consists of only three elements, Co, Pd, B, for the SUL, the seed layer, and the magnetic layer, has a very unique feature of the dull interfaces, observed by a transmission electron microscope.
MRS Proceedings, 2006
ABSTRACTThis work presents an annealing study of high-anisotropy (Co/Pd)N magnetic multilayers designed for bit-patterned medium recording applications. Magnetic multilayers were deposited by magnetron sputtering at 2.5mT argon pressure at room temperature and annealed at different temperatures (up to 250 °C) for up to 2 hours in atmosphere and in vacuum. Depending on the annealing time, the samples annealed in atmosphere exhibited two distinct modes of magnetization reversal. In samples annealed for a time shorter than some critical time, tc, where tc is a function of the annealing temperature, the magnetization reversal occurs by domain wall injection and propagation. In samples annealed for times longer then tc, the magnetization reversal mode switches to magnetization rotation. Using XPS, it is found that the transition is accompanied by the formation of oxidizes at the grain boundaries leading to exchange decoupling of the grains. In samples annealed at higher temperatures, the...