Origin of magnetization decay in spin-dependent tunnel junctions
Spin-dependent tunnel junctions based on magnetically hard and soft ferromagnetic layers separated by a thin insulating barrier have emerged as prime candidates for information storage. However, the observed instability of the magnetically hard reference layer, leading to magnetization decay during field cycling of the adjacent soft layer, is a serious concern for future device applications. Using Lorentz electron microscopy and micromagnetic simulations, the hard-layer decay was found to result from large fringing fields surrounding magnetic domain walls in the magnetically soft layer. The formation and motion of these walls causes statistical flipping of magnetic moments in randomly oriented grains of the hard layer, with a progressive trend toward disorder and eventual demagnetization.
McCartney
MR
Center for Solid State Science, Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1704, USA. IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, USA.
Dunin-Borkowski
RE
Scheinfein
MR
Smith
DJ
Gider
S
Parkin
SS