Electrodeposition of RE-TM (RE = La, Sm, Gd; TM = Fe, Co, Ni) films and magnetic properties in urea melt

Rare earth (RE)-3d transition metal (TM) films were codeposited in low temperature urea-acetamide-NaBr-KBr-RECl3-TMCl2. baths by potentiostatic electrolysis. Cyclic voltammetry is used to investigate the electrochemical behavior of RE(III) and TM(II) in baths on a Pt electrode. The reduction of TM(II) is an irreversible process. RE(III) cannot be reduced alone, but it can be inductively codeposited with TM(II). Some kinetic parameters are measured, e.g., the transfer coefficient alpha and the diffusion coefficient D-0 for TM(II). It is reasonably suggested that the RE-induced codeposition ability and efficiency is dominated by the electronegativity difference between RE and TM atoms. Moreover, it is found that the surface morphologies, the magnetic anisotropy and preferring orientation of the as-deposited RE-TM films depend strongly on the composition and potential. At last, it is observed that, there exists a clear anisotropy with easy magnetization along the plane of the RE-TM films. The magnetic anisotropy in amorphous RE-TM films should be due to the competing contributions from several factors, such as spin-orbit coupling, stress. etc. (C) 2008 Elsevier B.V. All rights reserved.