Fabrication of electro deposited Co nanowire arrays with perpendicular anisotropy

Co nanowire arrays have been electro deposited into polycarbonate membranes with nanosized pores at different voltages. By means of X-ray diffraction, electron diffraction, vibrating sample magnetometer, their microstructures and magnetic properties were investigated at full length. The sample prepared at - 1.2 V, 250 mA/cm(2) shows perpendicular anisotropy, but the one deposited at - 1.0V, 125 mA/cm(2) has no perpendicular anisotropy. This different magnetic behavior can be explained from their different microstructures. X-ray diffraction and electron diffraction evidence that the former sample is amorphous, and the latter is polycrystalline. In the polycrystalline sample, due to the competition of shape anisotropy and magnetocrystal anisotropy, the sample does not display perpendicular anisotropy. But magnetocrystal anisotropy is very small in amorphous sample, therefore, shape anisotropy plays a dominant role which leads to strong perpendicular anisotropy because of shape anisotropy. Furthermore, applying a magnetic field during deposition, Co grains will preferentially grow with c-axis along the wire axis, which also leads to strong perpendicular anisotropy. (C) 2001 Elsevier Science B.V. All rights reserved.