Spin-orbit interaction tuning of perpendicular magnetic anisotropy in L10 FePdPt films

The dependence of perpendicular magnetic anisotropy K-u on spin-orbit coupling strength xi is investigated in L1(0) ordered FePd1-xPtx films by time-resolved magneto-optical Kerr effect measurements and ab initio density functional calculations. Continuous tuning of K-u over a wide range of magnitude is realized by changing the Pt/Pd concentration ratio, which strongly modifies xi but keeps other leading parameters affecting K-u nearly unchanged. Ab initio calculations predict a nearly quadratic dependence of K-u on xi, consistent with experimental data. K-u increases with increasing chemical order and decreasing thermal spin fluctuations, which becomes more significant for samples with higher Pt concentration. The results demonstrate an effective method to tune K-u utilizing its sensitivity on xi, which will help fabricate magnetic systems with desirable magnetic anisotropy. (C) 2014 AIP Publishing LLC.