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

摘要

In structurally ordered magnetic thin films, the Curie temperature (T) 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 in high anisotropy L1 FePt magnetic thin films by substituting Rh into the Pt site. Rh substitution in L1 FePt modified the local atomic environment and the corresponding electronic properties, while retaining the ordered L1 phase. The analysis of extended x-ray Absorption Fine Structure spectra shows that Rh uniformly substitutes for Pt in L1 FePt. A model of antiferromagnetic defects caused by controlled Rh substitution of the Pt site, reducing the T is proposed to interpret this phenomenon and its validity is further examined by ab initio density functional calculations.