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.