Magnetic properties of L1_0 FePt thin film influenced by recoverable strains stemmed from the polarization of Pb(Mg_(1/3)Nb_(2/3))O_3–PbTiO_3 substrate

The magnetic properties and magnetization reversible processes of L1_0 FePt(3 nm)/Pb(Mg_(1/3)Nb_(2/3))O_3–PbTiO_3(PMN–PT) heterostructure were investigated by using the phase field model. The simulation results show that the magnetic coercivities and magnetic domains evolution in the L1_0 FePt thin film are significantly influenced by the compressive strains stemming from the polarization of single crystal PMN–PT substrate under an applied electric field. It is found that the magnetic coercivities increase with increasing of the compressive strain. A large compressive strain is beneficial to aligning the magnetic moments along the out-of-plane direction and to the enhancement of perpendicular magnetic anisotropy. The variations of magnetic energy densities show that when compressive strains are different at the magnetization reversible processes, the magnetic anisotropy energies and the magnetic exchange energies firstly increase and then decrease, the negative demagnetization energy peaks appear at coercivities fields, and the magnetoelastic energies are invariable at large external magnetic field with the energy maximum appearing at coercivities fields. The variations of the magnetoelastic energies bring about the perpendicular magnetic anisotropy so that the magnetoelastic energy is lower at the large external magnetic fields, whereas the appearance of magnetoelastic energy peaks is due to the magnetization-altered direction from the normal direction of the plane of the L1_0 FePt thin film at coercivities fields.