Morphology Controlled Magnetic Interactions of Porous Silicon Embedded Nanostructures

Abstract

In the frame of this work porous silicon templates with different morphologies, especially with respect to the roughness of the pore-walls are filled with diverse ferromagnetic metals to fabricate self-assembled three dimensional arrays of nanostructures (wires, particles) with distinct magnetic properties. The fabricated templates offer a quasi-regular self-assembled pore-arrangement with oriented pores. Also the pore-filling is self-assembled by electrochemical deposition and there are multiple possibilities to tailor the magnetic behavior of these systems such as material, morphology, inter particle distance or interfaces. One critical parameter for this purpose is the roughness of the pore walls and the surface of the metal structures, respectively. To vary the morphology of the templates also magnetic field assisted etching has been employed and a remarkable decrease of the dendritic pore growth has been achieved resulting in smoother pore walls. Within the pores of these templates ferromagnetic metals are deposited and the modification of the magnetic properties compared to metal structures embedded in conventional etched (without magnetic field) porous silicon templates has been figured out. The magnetic anisotropy between easy axis and hard axis magnetization could be increased significantly and furthermore the magnetic behavior becomes comparatively hard magnetic. These properties can be ascribed to less magnetic coupling between nanostructures of adjacent pores and modified stray fields due to less dendritic metal nanowires. The magnetic behavior of three dimensional metal nanowire/nanoparticle arrays with regard to morphological parameters as well as to the influence of the inner interfaces of the composites will be presented. The presented system is of interest due to the silicon base material and the broad tunability of the magnetic properties for integrated magnetic and magnetooptic devices.