Effect of pH and Boric Acid on Magnetic Properties of Electrodeposited Co Nanowires

Arrays of Co nanowires of diameter similar to 200 nm have been prepared by electrodeposition into nanopores of anodic aluminum oxide templates. X-ray diffraction confirms that these nanowires consist of mostly hexagonal close-packed (hcp) or face-centered cubic (fcc) grains or a mixture of both. Scanning electron microscope confirms that these nanowires are continuous and parallel to each other. The effect of boric acid and pH on the structural and magnetic properties of electrodeposited cobalt nanowires has been studied. When boric acid is not introduced into the electrolyte, high concentration of hydrogen is liberated, which results into the formation of disordered fcc Co at low pH. The high value of coercivity for the nanowires deposited at low pH is attributed to the formation of higher fraction of disordered fcc Co nanowires. The induced anisotropy is weak at high pH compared to low pH. This is attributed to the competition between shape and magnetocrystalline anisotropy of hcp phase.