Characterisation of magnetisation processes in Y–Co/Tb–Co amorphous bilayers from SQUID and TMOKE hysteresis loops

Abstract The effect of sperimagnetic Tb–Co on a bilayer Y–Co/Tb–Co was studied by SQUID and TMOKE hysteresis loops. The combination of these different measurement techniques and the use of a model for the dependence of the DW thickness ( δ ) on the magnetic field, as the inverse of the square root of the magnetic field, allowed us to get information on the DW formed at the interface region of the bilayer. Even based on a simple model, an excellent agreement between superficial magneto-optical and global magnetic data was achieved. As a result, the thickness δ of the DW at a given field ( δ ∼1000 A at H ∼15 Oe) and the exchange constant ( A ) for the Co–Co atom pairs were determined. A ranged from 1.1×10 −7 erg/cm at 150 K to 0.9×10 −7 erg/cm at 300 K.