Steep MR change in NiFe/Cu/Co trilayers

A field sensitivity of about 2%/Oe in magnetoresistance (MR) change has been observed in NiFe(6 nm)/Cu/Co(5 nm) trilayers. The MR change was accompanied with a sharp increase in resistivity before decreasing steeply for increasing fields. Thickness of the Ca spacer layer influenced the sensitivity of MR change. These results suggest an existence of interlayer coupling between the two magnetic layers. An analysis of this MR effect suggests that biquadratic coupling plays an important role in the steep MR change.