First-order reversal curves of magnetic recording tapes

The interaction and its variation between magnetic grains in two kinds of magnetic recording tapes are investigated by first-order reversal curves (FORC) and the \delta M method. The composition and microstructure of the samples are characterised by x-ray diffraction and scanning electron microscope. The FORC diagram can provide more accurate information of the interaction and its variation, but the \delta M curves cannot. The positive interaction field and the large variation of the interaction field have opposite effects on the \delta M curve.