Structural and magnetic properties of UHV-evaporated Fe/Tb multilayers: Effect of the substrate temperature - art. no. 094415

Two series of (Fe/Tb)(20) multilayers deposited at two temperatures (150 K and 300 K) were investigated at room temperature by x-ray diffraction, conv ersion electron Mossbauer spectrometry, and magnetic measurements. The Fe l ayer thickness is varying in a large range (0.9-5.3 nm), while the Th layer thickness is fixed to 1.9 nm. Because of the two different types of amorph ous modulated structures obtained at the two deposition temperatures, the c rystallization of the Fe layers occurs following two different processes fo r the two series. Then, when the Fe layers are crystallized, experimental M ossbauer and magnetic results indicate a similar layered structure with the same extension for the Fe-Tb inter-faces at the same Fe thickness. For bot h series, when the crystallization of the Fe layers occurs, an enhancement of the perpendicular magnetic anisotropy (PMA) produced by a sharpening of the interfaces is evidenced. The strong PMA observed in the thinner (bcc-Fe /Tb) multilayers grown at 300 K comes from the dominant interface anisotrop y compared to the volume anisotropy due to the thin bcc-Fe thickness. For ( bcc-Fe/Tb) multilayers the variation of the saturation magnetization as a f unction of the Fe thickness allows us to quantify the different magnetic zo nes inside the multilayers. The deduced anisotropy constants for the interf aces and the volume are K-S = 2.32 mJ/m(2) and K-upsilon = -1.76x10(6) J/m( 3).