R. Sugita

Micromagnetic Study on Influence of the Magnetic Field Direction on the Domain Structure in Stacked Media

The relation between the domain structure in stacked media and applied magnetic field direction was investigated by using micromagnetic simulation assuming that the interlayer exchange constant between the hard and soft layers changes depending on the direction of the magnetization. The interlayer exchange constant was set to maximum and minimum for the magnetization in perpendicular and in-plane direction, respectively. As a result, it was clarified that the stacked medium demagnetized with perpendicular field had simple domain structure, while that demagnetized with in-plane field consisted of domains including sub-domains in them. The stray field distribution from the calculated magnetization distribution almost coincided with the results of the MFM observation, namely, the amplitude of the field variation for the in-plane demagnetized medium was about half of that for the perpendicularly demagnetized medium and the cycle of the field variation for the in-plane and the perpendicularly demagnetized medium was almost equal.

Effect of Applied Magnetic Field Direction on Magnetic Cluster State of Perpendicular Recording Media

We investigated influence of applied magnetic field direction on magnetic cluster state of perpendicular recording media. As a result, cluster size estimated from MFM images did not change as the applied field angle changed. On the other hand, it was clarified that the stray field from the media decreased as the applied field angle from the perpendicular direction increased. The decrease of the stray field is presumed to originate from magnetic cluster including subdomains less than MFM resolution.

Effect of interlayer interaction on domain structure of CoPt stacked films with perpendicular anisotropy

The effect of interlayer magnetostatic interaction on the domain structure of CoPt (3u2009nm)/Pt (δPt nm)/CoPt (10u2009nm) stacked films having perpendicular anisotropy is investigated. The domain structure of the demagnetized CoPt stacked films is observed using magnetic force microscope. The Co80Pt20 stacked films with Pt interlayer thickness δPt less than about 20u2009nm have the maze domain similar to that of the film with δPt of 0u2009nm. This is because the top and bottom layers are connected by the magnetostatic interaction and the magnetization distribution of both layers is integrated. The domain structure of the films with δPt around 25u2009nm is mixture of the maze and irregular domains. For the films with δPt over about 30u2009nm, because the interaction between the top and bottom layers decreases, the irregular domain which is observed in the 3u2009nm thick CoPt single layer film appears. In the region where the domain structure changes from the maze domain to the irregular one, domain size steeply increases with increa...

Dependence of domain structure on applied field direction in stacked media

Domain structure of stacked media demagnetized with perpendicular or in-plane demagnetization field is investigated using MFM. For a demagnetized medium (sample A), the domain size is approximately 50u2009nm regardless of demagnetization field direction, while the contrast of the MFM image for the in-plane demagnetized sample is lower than that for the perpendicularly demagnetized sample. The domain of sample B where the cap layer was etched from the sample A is similar to that of the sample A in case of perpendicular demagnetization, which shows the domains of the cap and granular layers are integrated. Meanwhile, in case of in-plane demagnetization, the domain of the sample B is hardly observed, which suggests the domains of the cap and granular layers of the sample A are not integrated, and it is probable that the sub-domain structure is formed in the cap layer. The domain of sample C demagnetized in-plane after etching the cap layer from the stacked medium is hardly observed like the sample B, which shows...

Micromagnetic study on influence of the recording field direction on transition noise of stacked media

The change in magnetization at the transition and the transition noise of the stacked media recorded with a single pole head without a trailing shield (SPH) and a head with a trailing shield (TSH) were investigated by using micromagnetic simulation. As a result, it was found that the linearity of the transition was higher and the transition noise was lower for the medium recorded with the TSH as compared with the medium recorded with the SPH. This is because stronger in-plane recording field of the TSH caused many small reversed domains. The relation between the magnetization distribution of the transition area and the direction of the recording head field reflected the relation between the domain structure of demagnetized media and the direction of the demagnetizing field.