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A computer simulation method, based on the Landau–Lifshitz–Gilbert equation was developed in order to investigate the dynamics of magneto‐optical recording and the mark writing process for the rare earth‐transition metal amorphous magneto‐optical layer was subsequently analyzed. It was found that the writing process depends sensitively on the spot radius of the irradiation laser. This result is discussed considering the reverse magnetized domain shrinking force, due to radial direction variation of wall energy density in a cylindrical domain model and the characteristics of the magnetic parameters. The writing process is especially affected by the temperature dependence of parameters in the region near the Curie temperature.

It has been found that the interface wall energy density σw for exchange‐coupled trilayer (ECTL) media, which is a key characteristic in obtaining overwritable magneto‐optical media, is controlled by sputter etching the SiN underlayer. The sputter‐etching effect of the SiN underlayer on film surface morphology, magnetic anisotropy, σw, and overwrite characteristics in ECTL media has been investigated. The media consist of a polycarbonate substrate, a SiN underlayer, TbFe memory layer, a NdFeCo exchange coupling control layer, a GdTbFeCo writing layer, and a SiN protective layer. By measuring saturation magnetization and switching field for the writing layer, σw between the memory layer and the writing layer was determined, according to the exchange‐coupled double‐layer theory. The effective perpendicular anisotropy of the NdFeCo layer decreased with sputter etching of the SiN layer, whereas the interface wall energy density changed from 0.6 to 1.7 erg/cm2 as 50 A of SiN was sputter etched away. These effe...

Recording magnetic‐field sensitivity and readout stability for Tb/FeCo multilayer magneto‐optical (MO) disks, made by sputtering with Kr and Ar gas, were studied. The 100 Oe recording magnetic‐field sensitivity for Kr disks was obtained. The readout stability for Kr disk is superior to that for Ar disk. It seems that high readout stability for Kr disks is caused by the large wall coercivity and the large ratio of wall coercivity to nucleation coercivity.

An extraordinary magnetoresistance effect, linearly dependent on the external magnetic field, is observed in amorphous TbFeCo films. The electrical resistance jumps by δρ at magnetization reversal. δρ depends on Tb concentration and it becomes nearly zero at about Tb 26 at. % concentration. To clarify the Tb concentration dependence of δρ, the magnetic properties and the heat treatment effect are examined. It is found that the magnetic anisotropy field (Hk ) is maximum at about Tb 26 at. % and the gradient of linear magnetoresistance, δρ/(ρ0Hc), is proportional to the −Hk+ const, where ρ0 is the electric resistance in zero field, Hc is the coercive force, and the constant is about 100 kOe. The structural relaxation, a coercive force change by the heat treatment up to 200 °C, is examined. It is found that as δρ/(ρ0Hc) in the as‐sputtered state decreases, the coercive force change by the heat treatment decreases. The coercive force change is minimum at about Tb 26 at. %, where δρ/(ρ0Hc) becomes zero. These ...

The sputtering condition effect on interface wall energy σw in overwritable MO media has been investigated. The media consist of a polycarbonate substrate, a SiN underlayer, a TbFe or TbFeCo memory layer, a NdFeCo exchange coupling control layer, a GdTbFeCo complementary layer, and a SiN protective layer. Underlayer SiN sputter etching effect on σw and Ar gas pressure effect on σw for memory layer deposition were examined. The sputter etching rate was fixed to 13 A/min. By measuring saturation magnetization and switching field for the complementary layer in the M‐H loop, σw between the memory layer and the complementary layer was calculated according to the exchange‐coupled double‐layer theory.1 With increasing sputtering etching time, σw changes from 0.6 to 1.7 erg/cm2 at about 5‐min sputter etching. Correspondingly, not only does memory layer coercive force Hc change from 6.5 to 1.8 kOe, but also coercive squareness S* is improved. FE‐SEM observation reveals that the structureless uniform memory layer i...