The origin of the large perpendicular magnetic anisotropy constant Ku of Co3Pt alloy thin films is discussed. The films deposited onto Al2O3(0001), Al2O3(112̄0), and MgO(111) substrates held at 230–450 °C during deposition exhibit Ku of the order of 107 erg/cm3 at room temperature. While the one dimensional long range order parameter S estimated by x-ray diffraction is very consistent with the development of the perpendicular magnetic anisotropy in the films deposited at 380–450 °C, very little evidence is found to suggest the correlation between S and Ku for the lower deposition temperature range (230–380 °C). To explain this, a short range ordering is suggested to be responsible for the origin of Ku, similar to the cases in Pt72Co28 alloys. The magneto-optical polar Kerr activity of ordered Co3Pt film is found to be enhanced for both θK and ηK in the photon energy range from 2 to 4 eV.

Abstract4oNilPt multilayers were prepared by magnetron sputtering using Ar gas. Effects of Pt seedlayer and Ar sputtering pressure on magnetic and structural properties are investigated. Microstructures of multilayers were analysed using XRD and TEM. It was found that perpendicular magnetic anisotropy and coercivity increase with increasing either the thickness of Pt seedlayer or Ar pressure. The causes of increases in perpendicular anisotropy and coercivity are discussed in relation to the interface roughness, the curvature of layers and the columnar structures.

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CoxNi1−x/Pt multilayers with x=0.4 and 0.5 were sputtered onto Si substrates. Magnetic and spectroscopic magneto-optic measurements (1.4–5.2 eV) reveal a Kerr rotation up to −0.48° at about 4.5 eV for a sample with rectangular hysteresis loop, about 170 kA/m coercivity, and a Curie temperature of about 300 °C. Pt layers could be made extremely thin (2.9 Å) without loss of perpendicular anisotropy and rectangular hysteresis loop. Simulations show that the Kerr rotation peak shifts back from 4.5 to 3.9 eV with increasing number of bilayers.

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