Submicrometer Stripes and Bubbles in Amorphous Films
by P. Chaudhari, S. R. Herd
Lorentz microscopy is used to study amorphous thin films of Gd-Co-Au and Gd-Co-Mo having a range of Q values. Stripe and bubble formation are shown as a function of perpendicular bias fields and pulsed or rotating in-plane fields. In the presence of an in-plane field, stripes contain a pair of Bloch lines and break into rows of Bloch-line containing bubbles. A unichiral stripe, however, forms a unichiral bubble that is stable to higher perpendicular bias fields than are Bloch-line bubbles. Bloch-line rotation in bubble walls in the presence of external rotating fields is demonstrated, and Bloch-line motion due to sweeping in-plane walls is shown. The rare occurrence of four Bloch lines in a 0.2-μm bubble is observed, as is the pearl-like accumulation of multiple Bloch lines in walls of irregularly shaped domains.