Permanent magnetic MnBiRE0.1 (RE = Dy, Sm) evaporated films, crystal structure and magnetic properties as a function of film thickness

MnBiRE0.1 (RE = Dy, Sm) alloy films, which exhibit perpendicular anisotropy, with thickness ranging from 60 to 1200 nm have been fabricated by the thermal evaporation method. X-ray diffraction analysis has shown that the samples exhibit low-temperature phase (LTP) MnBi with a NiAs-type structure when the thicknesses of samples are less than 250 nm, however, the Bi3Mn2 phase, which is non-magnetic, also appears when the thicknesses are larger than 250 nm. The magnetic measurements have revealed that the saturation magnetization sigma(s) = 46-78 emu/g, remanence ratio r = 0.67-0.99, coercive force H-c = 3.2-7.3 kOe, and magnetic energy product (BH)(max) = 3.3-14.3 MGOe, depend on the film thickness. The coercive force H-c reaches a maximum when d = 400 nm. (C) 1998 Elsevier Science B.V. All rights reserved.