Ion induced magnetization reorientation in Co/Pt multilayers for patternedmedia

Co/Pt multilayer films with perpendicular magnetic anisotropy and large out -of-plane coercivities of 3.9-8.5 kOe have been found to undergo a spin reo rientation transition from out-of-plane to in-plane upon irradiation with 7 00 keV nitrogen ions. X-ray reflectivity experiments show that the multilay er structure gets progressively disrupted with increasing ion dose, providi ng direct evidence for local atomic displacements at the Co/Pt interfaces. This effectively destroys the magnetic interface anisotropy, which was vari ed by about a factor of 2, between K-S congruent to 0.4 erg/cm(2) and K-S c ongruent to 0.85 erg/cm(2) for two particular films. The dose required to i nitiate spin-reorientation, 6 x 10(14) N+/cm(2) and 1.5 x 10(15) N+/cm(2), respectively, scales with K-S. It is roughly equal to the number of Co inte rface atoms per unit interface area contributing to K-S. (C) 2000 American Institute of Physics. [S0021-8979(00)67908-2].