Magnetization Reversal and Direct Observation of Magnetic Domains on FePt Thin Films

In ferromagnetic thin films, the presence of an out-of-plane component of the magnetic anisotropy may induce a transition from planar to stripe-like magnetic domains above a critical thickness,
$t_{c}$
. Because of the changes in the domain structure, important changes in the magnetization reversal mechanisms are observed. We present the analysis of the magnetization reversal in FePt thin films, where this phenomenon is observed, through the experimental observation of magnetic domains by magnetooptic Kerr effect microscopy. The observed reversal mechanisms are strongly dependent on the thickness of the sample. For
$t\lt t_{c}$
, the reversal process is a combination of domain wall movement and rotation of domains. Meanwhile, for
$t\gt t_{c}$
, the stripe-domain structure determines the magnetization reversal.