High Performance Hard magnetic Nanocomposite Films

摘要

We have studied the tailoring of nanostructures of the hard-soft phase nanocomposite thin films prepared by multilayer sputtering and subsequent heat treatment. The multilayered thin films were produced by means of plasma sputtering with a multiple-gun DC- and RF- sputtering system. The as-deposited films were then heat treated in various processes including rapid thermal annealing (RTA). In this process, heating and cooling rates up to 200 K/s can be realized. Nearly ideal morphologies have been realized and as a consequence, very high energy products and high coercivity have been obtained. In this paper, we will present our resutls on FePt:Fe_1-xPt_x(x approx 0.3), Pr_2Co_7:Co and SmCo_x:Co(x = 3.5, 4,and 5) systems. We will discuss some important issues in the nanocomposite magnets including remanence enhancement, magnetic hardening ,the ideal nanostructure, the intergrain exchange coupling and the role of grain boundaries.