Pt Content Dependence of the Switching Field Distributions of CoPtCr-SiO2 Perpendicular Media Characterized by Subtracting the Effect of Thermal Agitation |
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Authors: | Shimatsu T Kondo T Mitsuzuka K Watanabe S Aoi H Muraoka H Nakamura Y |
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Affiliation: | Res. Inst. of Electr. Commun., Tohoku Univ., Sendai; |
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Abstract: | The switching field distributions (SFD) of CoPtCr-SiO2 perpendicular media as a function of Pt content were characterized by subtracting the effect of thermal agitation, and discussed in relation to the microstructure. DC demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the width of SFD, DeltaSFD, from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~ 10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaSFD characterized by subtracting the effect of thermal agitation, DeltaH 0/H0, were nearly half those of DeltaHr /Hr for 10-nm-thick media. DeltaH0/H0 was about 0.10 at 10 at%Pt content, and increased as the Pt content increased, reaching 0.17 at 30 at%Pt content. The increase in DeltaH0/H0 was probably caused by an increase in the stacking fault density and the formation of fcc layers in the hcp CoPtCr lattice. A simple calculation based on the coherent switching of magnetization revealed that the c-axis distribution results in DeltaH 0/H0 of about 0.08, independent of Pt content. These results suggest that the DeltaSFD due to the grain-to-grain anisotropy field variation was small, only 0.02-0.03 |
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