A magnetometer for the rapid and nondestructive measurement of magnetic properties on rigid disk media

A magnetometer that allows for rapid and nondestructive measurement of magnetic properties on rigid-disk media is described. A rotating wheel containing erase, record, and read heads generates a remanence transfer curve from which the remanence thickness product, the remanent coercivity, and the coercive squareness can be calculated. The measurement takes about 70 s and serves as an especially important tool for process engineers controlling the magnetic properties of the disk-sputtering process. The essence of the measurement is the readback analysis at different write currents of a 25- mu m-long recorded transition with width equal to the width of the record head (in this case 19 mm). By moving the disk to different positions, magnetic properties of rigid disks can be mapped.<
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