Direct observation of a magnetic domain change in Ni wire and film on a LiNbO3 substrate using X-ray magnetic circular dichroic photoemission electron microscopy

The magnetic domain structure modulation in Ni wires deposited on a LiNbO3 substrate is observed during the application of a DC current or heating. A striped domain structure is formed in the Ni wires that is aligned perpendicular to the X-axis of the LiNbO3 substrate owing to the competition between magnetic shape anisotropy and uniaxial magnetic anisotropy from the heterojunction. We observe that the striped domain structure disappears as the DC current is increased. In the same manner, it is also confirmed that the striped magnetic domain structure disappears as the substrate is heated. These results are considered to arise from the decrease in uniaxial magnetic anisotropy and magnetization owing to an oxidation reaction at the interface. Heterojunctions are identified to play an important role in controlling and modulating the magnetic properties of this system.