Properties and Structure of SmCoAlSi-based Trilayer for Longitudinal Recording Media

The introduction of the Cr interlayer caused magnetic decoupling in SmCoAlSi / Cr / SmCoAlSi and SmCoAlSi / Cr / SmCoCuTi thin films. High coercivity of 3400∼3840 Oe and extremely fine grain size in this two kinds of films were examined. Magnetic coupling within sublayers was introduced by using different substrate bias among the SmCoAlSi (deposited with substrate bias of -150 V) / SmCoAlSi (deposited with no substrate bias) / SmCoAlSi (deposited with substrate bias of -150 V) triple layers. This multilayer exhibited high coercivity ∼2960 Oe and S* 0.96. SmCoAlSi / SmCoCuTi / SmCoAlSi trilayer improved matching between the magnetic layer and the Cr underlayer, and led to increased in-plane anisotropy, high coercivity 3620 Oe and S* 0.91. The microstructures of these four kinds of media were also examined. Results obtained suggest that it is possible to produce SmCoAlSi-based multilayer media with the combined magnetic properties required for the ultra-high magnetic recording density of ∼20 Gbit/in2.