Element-specific magnetic properties of the epitaxial NiFe/Cr/NiFe trilayers

Ni and Fe L3,2-edge magnetic circular dichroism (MCD) and Cr K-edge x-ray absorption near-edge structure measurements have been performed for the Py/Cr(tCr)/Py (Py=Ni80Fe20) trilayers with tCr=5, 10, 15, 20, and 25 A. The MCD asymmetry ratios in the Ni and Fe L3-edges spectra are found strongly affected by the thickness of the Cr layer. The moments of the Fe and Ni 3d states are found, respectively, to decrease and increase suddenly when tCr increases beyond 20 A. The measured magneto-optical Kerr effect hysteresis loops show a ferromagnetic-to-antiferromagnetic phase transition at about the same Cr-layer thickness. The transition of the magnetic property is found to correlate with the structural transition of the Cr spacer layer from a pseudomorphic fcc-like structure to a bcc structure.