Magnetic Domain Expansion Readout for a Crescent-Shaped Domain

Magnetic domain expansion readout is studied without the presence of an alternative magnetic field. The reproduced waveform of a crescent-shaped domain 0.08 μm in length reaches 70% of the saturated signal level. However, a circular domain of 0.3 μm diameter does not expand so much. In the case of crescent domain expansion, it is considered that the copied domain shape is different from the original crescent shape in the recording layer, and that this reduces the magnetic energy. The assumption that the copied domain shape of the expansion layer becomes circular agrees well with the experimental result for the domain expansion ratio.