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 prepa red at - 1.2 V, 250 mA/cm(2) shows perpendicular anisotropy, but the one de posited at - 1.0V, 125 mA/cm(2) has no perpendicular anisotropy. This diffe rent magnetic behavior can be explained from their different microstructure s. X-ray diffraction and electron diffraction evidence that the former samp le is amorphous, and the latter is polycrystalline. In the polycrystalline sample, due to the competition of shape anisotropy and magnetocrystal aniso tropy, the sample does not display perpendicular anisotropy. But magnetocry stal anisotropy is very small in amorphous sample, therefore, shape anisotr opy plays a dominant role which leads to strong perpendicular anisotropy be cause of shape anisotropy. Furthermore, applying a magnetic field during de position, Co grains will preferentially grow with c-axis along the wire axi s, which also leads to strong perpendicular anisotropy. (C) 2001 Elsevier S cience B.V. All rights reserved.