Negative magnetic remanence in Co/Mn/Co grown on GaAs(001)

Co/wedged Mn/Co sandwiches were grown on GaAs(001) at room temperature. With the magneto-optical Kerr effect technique, magnetic hysteresis loops at different Mn thicknesses $(0l~dl~4\mathrm{nm})$ were measured and the negative remanence phenomenon was clearly observed when the magnetic interlayer coupling between the two Co layers was antiferromagnetic. The mechanism can be understood with the help of a well-defined model calculation, and the result indicates that such anomalous hysteresis loops are not frequently encountered because of the critical conditions required to realize them.