Tuning the Curie temperature of L1 ordered FePt thin films through site-specific substitution of Rh Available to Purchase

In structurally ordered magnetic thin films, the Curie temperature (T_C) 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 T_C in high anisotropy L1₀ Fe₅₀Pt₅₀ 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 T_C, is proposed to interpret this phenomenon and its validity is further examined by ab initio density functional calculations.