Electrocrystallisation of CoFe alloys under the influence of external homogeneous magnetic fields—Properties of deposited thin films

Abstract

The influence of homogeneous magnetic fields with flux density up to 1 T superimposed during the deposition of CoFe thin films on their properties has been studied. It has been clearly demonstrated that the superimposition of magnetic fields influences the resulting layer properties significantly. A pronounced impact on the layer morphology has been observed. The layers deposited under the influence of the parallel-to-electrode magnetic field appear denser and more homogenous than those obtained without a magnetic field. On the contrary, the layers deposited in the perpendicular-to-electrode magnetic field appeared more diverse. A scaling analysis revealed a smoothing effect of a parallel- and a roughening effect of a perpendicular-to-electrode magnetic field. No influence of magnetic fields neither on the deposited layers chemical composition nor the structure and texture has been found, whereas the internal stress state of the layer is affected by the superimposition. The effects are discussed with respect to the Lorentz force driven convection, which increases the electrochemical reaction's rates and improves desorption of hydrogen from the electrode surface. The alterations of magnetic properties of the CoFe thin films correlate well with the observed microstructural changes. Moreover, an in-plane magnetic anisotropy is induced by a parallel magnetic field superimposition. This phenomenon origins from a preferential next neighbour atomic pair-ordering in the direction of the magnetic field, e.g. magnetization, during deposition of the ferromagnetic alloy.