Nano-composite FePt-Al2O3 films for high-density magnetic recording

The magnetic properties and microstructures of the (Fe52Pt48)((1-x))-(Al2O3)(x) (x represents the volume fraction) films were investigated. It was revealed that the proper amount of alumina led to preferential (111) texture of L1(0) FePt phase in the films. With the increasing content of alumina, the coercivity squareness S* kept high at constant of about 0.9 when xless than or equal to25 vol%. and it decreased abruptly as x > 25 vol%. The grain size decreased from about 40 to 10 nm, and the coercivities deduced from 9.5 to 2.5 kOe due to the addition of alumina in the post-annealed films. Based on the measurement of the angular variation of coercivity and the relationship between activation volume and grain volume, it was suggested that, domain-wall pinning dominated the reversal process in the films with lower addition of alumina, while magnetization rotation took place prominently in the high-addition films. (C) 2002 Elsevier Science B.V. All rights reserved.