The Magnetic Stability of Spin-Dependent Tunneling Devices
S. Gider,
*
B.-U. Runge,
A. C. Marley,
S. S. P. Parkin
The tunneling resistance between two ferromagnetic metal layers
that are separated by a thin insulator depends on the relative orientation of the magnetization M of each layer. In a memory device, independent switching of the magnetically soft layer is
achieved by making the other layer either exchange-biased or
magnetically hard. The repeated reversal of M of the soft
layer by field cycling can demagnetize the other magnetically hard
layer and thus erase the tunnel junction's memory. The M of
exchange-biased structures was stable at least to 107
cycles, whereas in hard structures, M generally decayed logarithmically with the number of field cycles. The decay was very
sensitive to the thickness of the hard layer and the composition of the
soft layer. However, no decay was observed when the moment reversal was
accomplished by coherent rotation, establishing that demagnetization
results from the formation and motion of domain walls in the soft layer
during field cycling.
IBM Research Division, Almaden Research Center, 650 Harry Road,
K11/D2, San Jose, CA 95120-6099, USA.
*
Present address: IBM Storage Systems Division, 5600 Cottle Road,
N17A/142, San Jose, CA 95193, USA.
Present address: IBM Storage Systems Division, 5600 Cottle
Road, E44/15, San Jose, CA 95193, USA.
To whom correspondence should be addressed. E-mail:
parkin{at}almaden.ibm.com
