High Temperature and FORC Investigations of Semiconducting/Ferromagnetic Nanocomposites

In the frame of this work the temperature-dependency of the magnetization of various composite systems consisting of porous silicon (PSi) and silicon nanotubes (SiNTs) with embedded Ni, NiCo, FePt, and Fe3O4 structures is discussed. The temperature is varied between 80 and 1273 K which allows to determine the Curie Temperature of the composites which is higher than for the corresponding bulk materials. Magnetic cross-talk between metal deposits can be controlled by the morphology of the porous silicon (pore diameter and distance between the pores) or silicon nanotubes (inner diameter and wall thickness) and also by the distribution and size of the deposits within the pores. To get a clear knowledge about the magnetic interactions single hysteresis curves are not sufficient and thus first order reversal curves (FORC) are performed. Magnetic coupling is present for Ni, Co and NiCo deposits, whereas in the case of Fe3O4 and FePt nanoparticle loading no magnetic cross-talk between the particles is observed.