Magnetic and magneto-optical properties of (Pt/Co/Pt/Ni) multilayers

The Curie temperatures of Co-based multilayers which find application as magneto-optical recording media, are much higher than the optimum writing temperature of about 200 degrees C. Alloying Co with nickel has been projected as a viable solution to reduce the Curie temperature. However, perpendicular magnetic anisotropy energy, magnetization, and magneto-optical properties decrease upon alloying. In a novel approach we attempted to combine the features of Co/Pt multilayers with those of low Curie temperature Ni/Pt multilayers to develop low Curie temperature (Pti/Co/Pt/Ni) multilayers. We have deposited (Pt/Co/Pt/Ni) multilayers by d.c. magnetron sputtering and studied their magnetic and magneto-optical properties. The Curie temperatures of these multilayers were in the range of 150-300 degrees C, which are much lower than those of Co/Pt and (Co,Ni)/Pt multilayers. The Kerr spectra of these multilayers show enhancement at lower wavelengths with maxima around 3000 Angstrom. The magnetization of these multilayers was comparable to that of Co/Pt multilayers. These multilayers with low Curie temperatures, enhanced Kerr rotation at lower wavelengths, reasonable coercivities appear to be very interesting for application to magneto-optical recording media.