Effects of alloying element in Cr-based underlayer on magnetic properties of Co-Cr-Pt media

Magnetic layer thickness dependences of magnetic properties are investigate d for Co-Cr-Pt polycrystalline thin films with different Cr-alloy underlaye rs (Cr-Ti, Cr-W, Cr-Mo, Cr-V, Cr-Mo-V). The specimens with Cr-Ti, Cr-V, and Cr-Mo-V underlayers show higher coercivities by about 30% and lower activa tion magnetic moments than those with Cr-Mo underlayer. The effective diame ter of activation volume increases by 10-20% when the magnetic layer thickn ess is decreased from 12 to 8 nm. Temperature dependences of magnetic prope rties are also determined and discussed by referring to the data obtained u sing single crystal magnetic thin films with similar composition.