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Time Dependent Magnetic Switching in Spin Valve Structures

Published online by Cambridge University Press:  15 February 2011

J. B. Restorff ,
M. Wun-Fogle ,
S. F. Cheng  and
K. B. Hathaway
J. B. Restorff
Affiliation:
Naval Surface Warfare Center, 10901 New Hampshire Ave., Silver Spring, MD 20903
M. Wun-Fogle
Affiliation:
Naval Surface Warfare Center, 10901 New Hampshire Ave., Silver Spring, MD 20903
S. F. Cheng
Affiliation:
Naval Surface Warfare Center, 10901 New Hampshire Ave., Silver Spring, MD 20903
K. B. Hathaway
Affiliation:
Naval Surface Warfare Center, 10901 New Hampshire Ave., Silver Spring, MD 20903
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Abstract

We have observed time dependent magnetic switching in spin-valve sandwich structures of Cu/Co/Cu/Fe films grown on silicon and Kapton substrates and Permalloy/Co/Cu/Co films grown on NiO or NiO/CoO coated Si substrates. The giant magnetoresistance (MR) values ranged from 1 to 3 percent at room temperature. The films were grown by DC magnetron sputter deposition. Measurements were made on the time required for the MR to stabilize to about 1 part in 104 after the applied field was incremented. This time depends almost linearly on the amplitude of the timedependent MR change with a slope (time / ΔMR) of 20 000 to 30 000 s. Some samples took as long as 70 s to stabilize. The time dependent effects may be important for devices operating in these regions of the magnetoresistance curve. In addition, measurements were made on the time history of the MR value for a period of 75 s following a step change in the field from saturation. We observed that the time dependent behavior of the MR values of both experiments produced an excellent fit to a function of the form ΔMR(t) = α + β;ln(t) where ɑ and β are constants. This time dependence was consistent with the behavior of the magnetic aftereffect.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 384: Symposium L – Magnetic Ultrathin films, Multilayers and Surfaces , 1995 , 185
Copyright
Copyright © Materials Research Society 1995

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References

REFERENCES

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5.It is tempting to try to use something like ΔMR = α+ βln(t/τ) to find a characteristic time; however, due to the properties of the log function, this results in ΔMR = [α − ln(τ)] + βIn(τ) where the quantity in square brackets is just a constant. Thus the “characteristic time” is folded into the constant a.Google Scholar