Absfrucf -We report the dependence of the magnetization, anisotropy constant, and Kerr rotation on the Fe concentration in FexCol-JPd multilayer thin films, where the Fe concentration n varies between 0 and 100 percent with maintaining the same sublayer thicknesses of 2A FeCo and 9A Pd. Perpendicular magnetic anisotropy existed for the films having Fe concentration less than about 80 atomic percent. Enhanced magnetization, possibly due to the polarization of Pd, was observed in the full range of Fe concentration. No simple proportional relation between the Kerr rotation and the magnetization was observed in this system. I . INTRODUCTION Transition-metal (TM) based multilayer thin films have been the subject of numerous recent studies because of their novel properties such as perpendicular magnetic anisotropy [l-41 and the giant magnetoresistance [5]. Potential application to magneto -optical recording on the materials with perpendicular magnetic anisotropy has triggered a lot of investigations on these systems [6-81. So far the studies have been limited to TM element -based systems and little attention has been paidtoFeCoalloysystems. Inthispaper, wereportmagneticand magnetooptical properties of FeCoPd multilayer thin films and discuss a possibility to utilize these materials for magneto-optical recording media. II. EXF'ERJMENT Samples were prepared by e-beam evaporation of FeCo alloy and Pd element on glass substrates in a vacuum chamber maintained at about 2X low6 Torr during the deposition. The multilayer structure was achieved by alternately exposing the substrate to each of the two e -beam sources via a rotating substrate mount. Two e-beam sources were physically separated by stainless shields to prevent cross contamination of their evaporated fluxes. The deposition rates from the two sources were monitored by corresponding quartz crystal sensors. A typical deposition rate was 1 AIS with an average fluctuation of 10 % for FeCo and 4.5 AIS with an average fluctuation of 2 % for Pd. The Fe concentration in the FeCo sublayer was varied by evaporating FeCo alloys having different compositions. Although the composition was varied, the sublayer thicknesses of 2A FeCo and 9A Pd were kept constant in all samples.The film composition was determined by inductively coupled plasma (10) atomic emission spectrometry and the film structure, was investigated by 8 -28 scanning x-ray diffractometry. Magnetization was measured using a vibrating sample magnetometer (VSM) calibrated against Ni standard. The magnetic anisotropy was measured using a torque 1