Effect of Cr(100-x)Ti(x) (x=0-19 at.%) alloy underlayers on the high coercivity of FePt thin film below the substrate temperature of 250 degrees C

Abstract

The effect of Cr100-xTix underlayer on orderd-L1(0) FePt films was investigated. A low-temperature ordering of FePt films could be attained through changing the Ti content of Cr100-xTix underlayer. The ordering temperature of the 30 nm FePt film grown on 20 nm Cr90Ti10 underlayer was reduced to 250 degrees C which is practical manufacture process temperature. An in-plane coercivity was very high to 6000 Oe and a ratio of remnant magnetization (M-r) to saturation magnetization (M-s) was as large as 0.85. This result indicates that the coercivity obtained at 250 degrees C by the effect of CrTi underlayer is significantly higher than those obtained at 250-275 degrees C by the effect of underlayers in other conventional studies. The prominent improvement of the magnetic properties of ordered FePt thin films at low temperature of 250 degrees C could be understood with considering the strain-induced ordering phase transformation associated with lattice mismatch between Cr underlayer and FePt magnetic layer due to an addition of Ti content. (C) 2011 Elsevier B. V. All rights reserved.