Nanostructure and magnetic properties of \u3ci\u3eL\u3c/i\u3e1\u3csub\u3e0\u3c/sub\u3e FePt:\u3ci\u3eX\u3c/i\u3e films

Nonepitaxial FePt: X films (X =Cu,Au,CuAu) with tunable magnetic properties are fabricated and investigated. Emphasis is on controlling and adjusting the magnetic properties of high-density perpendicular recording media through exchange decoupling and anisotropy. The films are initially deposited as multilayers with the structure [FePt&#;X]n and have individual thicknesses from about 0.06 to 1.1 nm. To create an (001)-oriented granular L10 structure, the films are then annealed at temperatures of 600 °C for 5 min and 550 °C for 10 min. The data indicate that Cu enters the L10 lattice whereas Au segregates at the grain boundaries and reduces the intergranular exchange coupling. For X=CuAu, we obtain coercivities Hc below 10 kOe, and slopes α =(dM&#;dH)Hc of about 1. For X=Cu, we find a favorable reduction in Curie temperature and Hc