Formation of Columnar-Shaped Structure of Fe in Fe--Cr--Sn Thin Films and Its Shape-Magnetic Anisotropy

In this work studied has been the fabrication method of columnar-structured Fe thin film for manifestation of a shape anisotropy in Fe--Cr alloy system, in which the phase separation occurs naturally by the thermal treatment. In order to obtain such a columnar structure, we have utilized the phase separation on a Sn-nanoparticle-dispersed Si substrate, by exploiting an excellent metallurgical affinity of Fe and Sn, and moreover we have employed applying an external magnetic field. Resultingly, we have found that the columnar-structured Fe thin films are likely to be formed after annealing. Thus obtained Fe--Cr--Sn thin film was found to exhibit a high shape-magnetic anisotropy, where the out-of-plane coercivity $H_{\text{c}\bot}$ was about 750 Oe, being five times larger than the in-plane coercivity $H_{\text{c}\|}$ of about 150 Oe.