ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We proposed a new type of magnetoresistive random access memory (MRAM) using a weakly coupled GMR effect. It operates on the general principle of storing a binary digit in hard component and sensing its remanent state by switching the soft component in such a way that the magnetic state of the hard component is unaltered. It is believed that this structure could have nondestructive readout (NDRO) characteristics. However, in experiments we found that NDRO was not always achieved; i.e., NDRO was dependent on the polarity of the excitation field. We take an example for mode "0'' (corresponding to a + remanent state). Although tests involving 3×108 plus excitation pulses indicated that the element was still stable, stability against minus disturb pulses could not be expected. The remanent state of 0 was degrading gradually and was finally destroyed after nenormous numbers of readout switching. An analytical model, in which the hard component follows the Rayleigh law, can explain the above phenomenon. It is because the irreversible magnetization processes cause disturbed states (0′ or 1′). Obviously the worst case for mode 0 is being excited by continous minus pulses whereas the worst case for mode 1 is being excited by continous plus pulses. We think that two methods will be effective to eliminate the unstability. One is to obtain a rectangular hysteresis loop for the hard component. The other is to imporve the excitation method, for example, to employ bipolar pulses for excitation signals. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.362444
