Magnetoresistance controls of arborous bead-dendritic growth of magnetic electrodeposits - Experimental and theoretical results

The effect of magnetic fields applied on magnetic metals electrodeposition was examined. Nickel deposits obtained from a Watt solution with coumarin, at cathodic potentials of -1000, -1200, and -1300 mV/SCE, without and with, both, perpendicular and parallel oriented to the electrode surface low applied magnetic fields (up to 500 Oe) were examined by scanning electron microscopy (SEM) technique. At a potential of -1300 mV/SCE, a dramatic difference was observed between nickel morphologies obtained with a perpendicular oriented magnetic field (zero MHD effect) and those obtained in the absence of one. The nickel deposit obtained with perpendicular oriented magnetic fields was a very developed 3D arboreous-bead-dendritic structure. On the other hand, the nickel deposit obtained without the presence of magnetic field was very rough, with a clearly visible clustered structure. The obtained nickel morphologies are then compared with copper morphologies. Based on the fact that copper deposits obtained with and without a perpendicular oriented magnetic field were dendritic structures, the observed difference between nickel deposits with and those without a perpendicular oriented field, is essentially ascribed to the magnetoresistance effect on the magnetic deposits, which are nonexistent in nonmagnetic materials. We also have done experiments with iron deposits. (C) 2004 The Electrochemical Society.