A magnetic film memory element for fully unipolar operation

Abstract

The most generally known mode of operation of a thin-film memory uses unipolar field pulses in the hard direction and positive and negative field pulses in the easy direction for writing. For reading, unipolar field pulses are applied in the hard direction, and according to the stored information, a positive pulse followed by a negative one or vice versa are induced in a sense line. The circumferential electronic circuitry is rather complex, as bipolar bit drivers and sense detectors are required. Savings in driving and detecting circuitry are possible with an element which requires bit drive pulses of only one polarity, and produces a sense signal for a binary "1", but no sense signal for a binary "0". An element satisfying the above requirements will be described. It consists of two magnetic Ni-Fe layers evaporated on top of each other, which are separated by a thick SiO layer. The easy axes of both magnetic layers form a small angle with each other. Preliminary experience with this new memory element, with respect to its preparation, physical behavior, and pulse operation, is discussed. © 1966 The American Institute of Physics.