THIN MAGNETIC FILM STORAGE DEVICES
Date
1965-11
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Degree Level
Doctoral
Abstract
Binary information may be represented by domains in a thin uniaxial magnetic film. By means of suitable sequences of applied fields domains may be propagated to a point where their data -representing state may be detected. The. characteristics of devices working on the principle have been investigated for different modes of operation. The nucleation and subsequent morphology of domains has been studied with particular regard to the modes in which. spurious changes occur the data-representing states of
domains as they are propagated. The operating tolerances on the magnetic driving fields depend on the difference between Hs, the field required to nucleate domains, and Ho, the field required to move domain boundaries. -1-k corresponds to the anisotropy field, Hk. By increasing the uniaxial anisotropy, by changing the film composition, r may be considerably • increased. Hc, may be controlled independently by varying the film thickness. Spurious changes in the data -representing states of domains are caused by magnetostatic interactions during relaxation of the domains after the driving field pulses terminate. These magnetostatic effects may be modified by a magnetic biassing field, which results in a considerable increase in operating tolerances. Applications for sequential-access devices employing domain wall motion are considered and shown to be most suitable for relatively small memory systems.
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Degree
Doctor of Philosophy (Ph.D.)
Department
Electrical Engineering