Magnetic tuning of hysteresis loop properties in antiferromagnetically coupled bilayers

We have utilized antiferromagnetically coupled bilayer structures to magnetically tune hysteresis loop properties. A key element of this approach is the nonoverlapping switching field distribution of the two magnetic layers, which allows for the measurement of magnetic reversal of the soft Co film at low fields while keeping the magnetization state of the hardmagnetic CoPtCrB film unperturbed. The effective disorder level in the Co film can be tuned easily by applying an appropriate field sequence to set the desired magnetization state of the CoPtCrB layer prior to hysteresis loop measurements of the Co film. This tuning procedure is fully reversible, temperature independent, and highly effective. (C) 2004 American Institute of Physics.