MFM Observation of High Coercivity in Nanostructured Tetragonally Distorted FeCo Films

The hard magnetic properties of nanostructured tetragonally distorted FeCo films, which have a relatively high magnetic anisotropy of ~10
⁶
J·m
^-3
, were investigated to reveal the mechanism of coercivity. FeCo nanodots with a diameter of 50 nm and thickness of 20 nm were fabricated using electron beam lithography. Magnetic force microscopy (MFM) revealed that the FeCo nanodots were magnetized perpendicularly, and that magnetization reversal occurred individually. The magnetization curve of the nanodots was obtained from the MFM results, and the coercivity was found to be 0.60 T, which was lower than the theoretically obtained value. The mechanism of the coercivity reduction is discussed.