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Volume 25, Issue 7
Displaying 1-3 of 3 articles from this issue
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Contributed Paper
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M. Kaneko, A. Nakaoki, T. Kobayashi2001 Volume 25 Issue 7 Pages 1393-1398
Published: 2001
Released on J-STAGE: February 02, 2007
JOURNAL OPEN ACCESSThe stripe domain structure in a readout layer with a small perpendicular anisotropy in CAD media was calculated on the basis of three proposed stripe domain models. Without a magnetic field, the triangular-cross-section stripe domain appears only in the narrow range of Q=Ku/(2πMs2), but when a leakage field of 100 Oe is applied from the memory layer, it becomes stable for a wide range of Q values below a critical value. For Q values above a critical value, the trapezoidal-cross-section stripe domain is stable. The distribution of the stable domain structure in the readout light spot was calculated, using the temperature profile and temperature dependence of magnetic parameters, on the basis of molecular field theory. The results show that a single domain in the perpendicular direction is stable in the spot’s center for a leakage field of 100 Oe, and that triangular stripe domain area is expanded in the spot’s circumference for a leakage field of 200 Oe. The result is discussed in relation to the copying process and the gray masking phenomenon.View full abstractDownload PDF (328K) -
T. Tanaka, T. Suzuki2001 Volume 25 Issue 7 Pages 1399-1404
Published: 2001
Released on J-STAGE: February 02, 2007
JOURNAL OPEN ACCESSThe high-density recording performance and thermal stability of super-fine particulate Ba-ferrite media are investigated. The smallest particles have an average diameter of 22.7 nm. In the first part of the paper, an excellent recording capability for small-particle media is described. A D20* value greater than 250 kFRPI has been ascertained at the present spacing of 47 nm. Next, inter-particle interaction, determined through ΔM measurement, and thermal stability in terms of magnetization time decay measurement are discussed. The Street and Woolley method and the waiting time method are compared in relation to estimating the activation volume for super-fine particulate media. It is shown that inter-particle interaction greatly affects the magnetization time decay and activation volume.View full abstractDownload PDF (445K) -
H. Yamamoto, T. Yamane2001 Volume 25 Issue 7 Pages 1405-1409
Published: 2001
Released on J-STAGE: February 02, 2007
JOURNAL OPEN ACCESSAmorphous melt-spun ribbons of Didymium-Fe-Co-Nb-B alloys were prepared by the single-roller rapid-quenching method. The effects of the composition, wheel velocity, and heat treatment on the magnetic properties were investigated. Amorphous Didymium9-Fe76Co8Nb1B6 ribbons prepared at a wheel velocity of 20 m/s were crystallized by heat treatment, and the optimum heat treatment condition was found to be 625°C for 5 min, in which case the value of (BH)max was 147.3 kJ/m3. The temperature coefficients of Br and HcJ for ribbons of crystallized Didymium9-Fe76Co8Nb1B6 alloy were α(Br)= -0.087%/°C (reversible) and α(HcJ)= -0.416%/°C (irreversible), respectively. The value of (BH)max for a compression molded Didymium9-Fe76Co8-Nb1B6 isotropic bonded magnet prepared by using the ribbons annealed at 625°C for 5 min was 79.7 kJ/m3.View full abstractDownload PDF (338K)
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