Tubular magnetic nanostructures based on glancing angle deposited templates and atomic layer deposition

A route for the fabrication of magnetic nanotubes is established by combining glancing angle deposition (GLAD) and atomic layer deposition (ALD). In a first step, arrays of inclined or upright columnar Si structures are deposited using a glancing angle ion beam sputter technique. In a second step, these columns are covered with Fe2O3 by means of ALD, thus fabricating tubular structures with well defined wall thicknesses that envelop the Si columns. Subsequent reduction in Ar/H-2 atmosphere converts the Fe2O3 tubes to ferrimagnetic Fe3O4 tubes. Using superconducting quantum interference magnetometry, the orientation dependence of the coercive field is extracted from magnetization isotherms, recorded on asfabricated samples oriented at various angles with respect to the magnetic field. We find an angular dependence in the variation of the coercive field, which is related to the inclination angle of the columns. [GRAPHICS] Cross-sectional scanning electron micrograph of a zigzag Si structure. columnar (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim