Structure and magnetic switching of thin-film a-HITPERM/Si[O.sub.2] soft magnetic multilayers

Laminated [([Fe.sub.0.7][Co.sub.0.3]).sub.88][Zr.sub.7][B.sub.4][Cu.sub.1] amorphous HITPERM/Si[O.sub.2] multilayer thin films have been studied by room-temperature (RT) pulsed inductive microwave magnetometry (PIMM) in single, bilayer, and trilayer films. Switching has been measured in a multilayer film with six (50 nm) HITPERM layers, separated by five (2 nm) Si[O.sub.2] layers. Films were investigated by conventional transmission electron microscopy (TEM), high-resolution TEM (HREM), and superconducting quantum interference device (SQUID) magnetometry. HREM and TEM show BCC FeCo nanocrystals to nucleate on top of Si[O.sub.2] layers. Plan view TEM on the top layer reveals FCC nanocrystals that align in chains with spacing of ~50-100 nm. SQUID magnetometry shows reversal to begin by rotation in a single layer for H < 14.4 kA/m (180 Oe) followed by nearly simultaneous reversal of several layers. A final switching event is thermally activated, requiring fields in excess of 8 kA/m (100 Oe) to switch at 2 K, but switching at the same field as other layers for elevated temperatures (RT). Index Terms--Multilayers, PIMM, soft magnet, thermally activated switching.