Thin film magnetic material - with cobalt-nickel alloy and oxide as ferromagnetic and antiferromagnetic phases in alternating layers

摘要

The magnetic matls., for magnetic recording media, consisting of a non-magnetic substrate and =2 layers, one of a ferromagnetic phase A and one of an antiferromagnetic phase B, which have a common boundary and thus are coupled magnetically, so that a remanence of different value occurs after satn. in the 2 magnetic polarisation directions below a characteristic temp., the Neel temp., have the alloy CoxNi-x as phase A and the oxide (CoO)x(NiO)1-x as phase B (in which x = 0.04-0.98). The layers of phases A and B pref. are 100-2000 angstrom and 40-2000 angstrom thick respectively and a no. of alternating layers can be used. The layer next to the substrate can contain either phse A or phase B. The matls. have an asymmetrical hysteresis loop, due to the effect of exchange anisotropy, and the Neel temp. can be controlled within wide limits by the compsn.