Simulation of Thermomagnetic Recording Process Using MFM Method: Effect of Field Gradient

• Published in: Transactions of the Magnetics Society of Japan 2004/11/01, Vol.4(4-2), pp.172-177
• Main Authors: Kato, T., Shimodaira, M., Koyama, T., Tsunashima, S., Iwata, S.
• Format: Article
• Language: English
• Subjects: Huth's model; hybrid recording; TbFeCo; thermomagnetic recording process
• ISSN: 1346-7948; 1884-6726
• DOI: 10.3379/tmjpn2001.4.172

Thermomagnetic recording process was simulated for Tbc(Fe72Co22)100-c media by using Huth's model modified to be applied to the magnetic field modulation (MFM) recording method. In the case of the recording with 0.4μm-diameter laser spot and a single pulsed uniform recording magnetic field and TbFeCo media, the recorded mark length became much longer than designed one calculated by a linear velocity and a field pulse width, when the designed mark length was less than 100 nm. The mark elongation was more significant for the recording on a TM-rich medium (c=17.6). When the mark length was shorter than 40 nm, marks were not formed on a RE-rich medium (c=21.7) due to the collapse of domains. By introducing Gaussian profile of recording magnetic field with a maximum gradient of 10 Oe/nm together with the laser spot profile, the elongation of recorded marks was remarkably reduced. Furthermore, the stability of the marks shorter than 40 nm on the media c=21.7 was found to be improved. From the analysis of the effective field acting on the domain wall, it was found that the effect of the field gradient |∂Hc/∂χ|+|∂Hext/∂χ| at the wall stable position was crucial to reduce the mark elongation as well as to improve stability of very short marks.