Annealing Effects on the Magnetic Anisotropy of FePt/BaTiO3 Bilayers

M RODRIGUEZ; M. CABABIE; A. PEDROSO; L. STEREN; D. RUBI; A. BUTERA; J. GOMEZ; M. SIRENA

Conferencia; Materials Research Society Fall Meeting; 2015

Recent ab-initio calculations performed on FePt/BaTiO3 heterostructures remark on an important change of the magnetic anisotropy of FePt induced by the ferroelectric polarization of the BaTiO3 [1]. M. Lee and coworkers found that the electronic structure of Ti is spin-polarized at the FePt/BaTiO3 interfaces and that this effect strongly depressed the magnetic anisotropy of the FePt. The change of the magnetic anisotropy was assigned to the hybridization state of Fe-Ti atoms. The simulations were performed considering an L10-ordered (P4/mmm) FePt alloy. In this phase, the FePt shows a high magnetic anisotropy. However, it is well-known [2] that FePt thin films deposited by sputtering grow in a chemically disordered fcc crystallographic phase (A1). As expected, the as-deposited films display soft magnetic properties. In order to examine the change of the structures anisotropy with the crystalline structure and underlayer-induced strains, we have investigated the magnetic and structural properties of FePt/BaTiO3 bilayers of different thickness and after different annealing treatments. For the study, a series of FePt tFePt/BaTiO3/Pt/Ti/SiO2/Si(100) structures with tBaTiO3=250nm and 20nm