Ferromagnetic Zr 1− xMn xCo 2 laves phase compounds

Abstract

Structure and magnetic properties of the Zr 1− x Mn x Co 2+ δ alloys were studied for 0 ⩽ x <0.7, δ=0, 0.45. The cubic C15 Laves phase structure shows Mn solubility up to x≈0.4. The other Laves phase with the hexagonal C36 structure found for x⩾0.5 apparently has a small region of Mn solubility in the vicinity of Zr 0.4Mn 0.6Co 2. Though the parent Mn-free compounds are known to be paramagnetic, the Mn-substituted alloys show ferromagnetic behavior with the Curie temperatures up to 625 K and the room-temperature saturation magnetization of about 100 emu/g. The onset of ferromagnetism with the Mn substitution for Zr may be caused by polarization of itinerant 3d electrons, like it was earlier supposed for the off-stoichiometric ZrCo 2+ δ . The universal composition dependencies of the intrinsic magnetic properties for different δ can be obtained, if plotted against the amount of zirconium atoms missing in its sublattice. The room-temperature anisotropy with the noticeable anisotropy field of 24 kOe and the 〈1 1 0〉 easy magnetization direction laying in a basal plane was found in the hexagonal Zr 0.5Mn 0.5Co 2.