Switching field distributions and ΔM measurements for perpendicular media

A new experimental method has recently been proposed to determine the switching field distribution for perpendicular media. The advantage of the new technique is that it separates the effects of the switching field distribution and the effective demagnetization factor, which are difficult to estimate independently. In this paper, this methodology is extended to the ΔM measurement, which is an indicator for intergranular exchange interactions. We present the magnetic properties for a set of CoCrPt alloy media and a set of [CoX-Pd]_N based multilayer perpendicular media. We correlate the effective demagnetization factor and the width of the switching field distribution to the exchange interaction and recording performance.