Tuning the Curie temperature of L10 ordered FePt thin films through site-specific substitution of Rh.

In structurally ordered magnetic thin films, the Curie temperature (TC) of ferromagnetic films depends on the exchange integral of the short range ordered neighboring atoms. The exchange integral may be adjusted by controlling the elemental substitutional concentration at the lattice site of interest. We show how to control the TC in high anisotropy L10 Fe50 Pt50 magnetic thin films by substituting Rh into the Pt site. Rh substitution in L10 FePt modified the local atomic environment and the corresponding electronic properties, while retaining the ordered L10 phase. The analysis of extended x-ray Absorption Fine Structure spectra shows that Rh uniformly substitutes for Pt in L10 FePt. A model of antiferromagnetic defects caused by controlled Rh substitution of the Pt site, reducing the TC, is proposed to interpret this phenomenon and its validity is further examined by ab initio density functional calculations. [ABSTRACT FROM AUTHOR]