Paper MI-WeM5
High Magnetization FeCo/Pd Multilayers

Wednesday, October 17, 2007, 9:20 am, Room 619

A high saturation magnetization is advantageous in magnetic recording. For the 3d ferromagnets, the peak of the Slater-Pauling curve corresponds to BCC FeCo, with a saturation magnetization of 2.45 T. Recently, a magnetization of 2.57 T in the FeCo layers of a [40 nm Fe₇₀Co₃₀ /1.7 nm Pd]x25 superlattice has been reported.^1,2 This result may be attributed to an enhanced Fe moment due to interfacial strain and an accompanying induced moment in the Pd. We have fabricated multilayer samples with varying superlattice periodicity and interlayer thicknesses to determine the nature of the enhanced moment in this intriguing thin film system. Magnetic characterization experiments show an enhanced magnetic moment in the multilayers as compared to a film containing the same amount of FeCo. However, since the magnetization is defined as the magnetic moment divided by the sample volume, the sample exhibits an overall reduction in the magnetization when the volume of the Pd layers is also taken into account. Our experimental findings are also supported by theoretical calculations which identify the origin of the increased magnetic moment in the multilayer system. Polarized neutron reflectivity experiments will be used to determine the lateral distribution of the magnetization in a number of superlattice samples.³.

¹ K. Noma, M. Matsuoka, H. Kanai, Y. Uehara, K. Nomura, and N. Awaji. IEEE Trans. Magn. 42, 140 (2006).
² ibid. 41, 2920 (2005).
³ This project was funded by grants from the DOE, the INSIC EHDR Program, and NSF-DMR 0213985 .