Abstract
Magnetic tapes used for credit cards and for identification and access control cards are migrating to extremely high coercivites (3000–4000 Oe) in order to avoid accidental erasure and demagnetization problems. These new media employ longitudinally oriented assemblies of Ba-ferrite platelet-shaped particles. Under certain conditions cards made with such media exhibit asymmetries in the forward/reverse waveforms which can cause decoding errors, particularly when read with a commercial swipe reader using integration decode electronic. We found that a systematic tilt of the easy axes of the particles away from the longitudinal direction can cause forward/reverse read waveform asymmetry. Furthermore, large waveform distortions can result from the perpendicular magnetization component in poorly oriented media.
Published Version
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