MAGNETIZATION REVERSAL PROCESS OF STRONTIUM FERRITE DOT ARRAYS

摘要

Patterned magnetic media where magnetic bits are recorded on isolated single domain islands is one of the promising candidates for extending magnetic recording density. Most of the patterned media are based on magnetic metals or alloys and fabricated to nanometer arrays by electron beam lithography or focused ion beam system. Here we present our proposal for patterned media based on hexagonal ferrite. Nonmagnetic ferrite precursor was deposited into patterned holes fabricated onto PMMA by electron beam lithography. Magnetic dot were obtained by annealing followed by lift-off process. The obtained samples were characterized by magnetic force microscopy (MFM) and superconducting quantum interference device (SQUID). The magnetization configuration in the dot is strongly confined by the dot size. With the dot size decrease to about 500 nm, we can only see black or white contrast for every dot, which indicate the dot to be single domain. Magnetic measurement shows the magnetic reversal mechanism is changing from domain wall movement to magnetization rotation with decrease of dot size. Our result proved ferrite dot arrays are competitive candidates for future ultra high density magnetic recording media.