Electrochemically deposited cobalt/platinum (Co/Pt) film into porous silicon: Structural investigation and magnetic properties

A nanostructured CoPt magnetic film was deposited from a single electrolyte into porous silicon layer by an electrochemical technique, followed by annealing at 600 degrees C in Ar atmosphere during which the CoPt alloy was converted to L1(0) ordered phase. Porous silicon with pore diameter between 5 and 100 nm was firstly fabricated by galvanostatic anodization of n-type silicon wafer in the presence of CrO3 as oxidizing agent and ethanol or sodium lauryl sulfate as surfactants. The role of the surfactant on the produced pore size and morphology was investigated by means of UV-vis spectra. As-formed porous silicon was consequently used as a template for the electrodeposition of magnetic CoPt film. The phase formation, microstructure and the magnetic properties were fully analyzed by XRD, FE-SEM, EDS and VSM measurements. It was found that, upon annealing the coercivity was significantly increased due to the transformation to the L1(0) ordered structure. The saturation magnetization and remanence ratio were also found to increase, indicating no loss of Co content or oxidation reaction after the annealing. Results of synthesis and characterization of CoPt/porous silicon nanocomposite are addressed and thoroughly discussed. (C) 2012 Elsevier B. V. All rights reserved.