Magnetic force microscopy study of dense stripe domains in Fe-B/Co-Si-B multilayers and the evolution under an external applied field

The effect of the permanent compression acting on multilayered Fe-B/Co-Si-B thin films has been studied by using magnetic force microscopy (MFM). Since both materials exhibit positive and negative saturation magnetostriction, respectively, the magnetic-moment distribution and thus the domain structure of these multilayers are strongly dependent on the thickness of each layer. Different MFM contrast levels and domain sizes have been measured in stressed and unstressed multilayers with various Fe-B and Co-Si-B layer thickness. Both kinds of samples, stressed and unstressed thin films, present a weak perpendicular anisotropy. For identical composition of the multilayers, an increase of the magnetization component perpendicular to the sample plane has been observed in stressed samples compared to their unstressed counterparts. In addition, the effect of the stress on the magnetization process has been studied by analyzing the evolution of the domain structure with an externally applied magnetic field in MFM imaging.