Title :
Temperature dependence of the coercivity of Fe films sputtered on nanochannel alumina
Author :
Butera, A. ; Weston, J.L. ; Barnard, J.A.
Author_Institution :
Dept. of Metall. & Mater. Eng., Alabama Univ., Tuscaloosa, AL, USA
fDate :
7/1/1998 12:00:00 AM
Abstract :
The morphology, magnetic microstructure, and temperature dependence of the magnetic coercivity of Fe films sputter deposited on commercial nanoporous substrates has been examined. Images obtained using Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) showed that the films grow in the form of a contiguous ferro-magnetic network of small interconnected grains on the walls that separate the nanopores. Magnetic Force Microscopy (MFM) showed a very complex domain structured with magnetic clusters much larger than the grain size. This complexity in the magnetic structure is not unexpected if the network-like shape of the films is considered. The coercivity of all films increases as the temperature is decreased, the largest variation occurring for a film 5 nm thick. Maximum coercivities Hc ~1800 Oe at 30 K were obtained in as-deposited 5 mn films. The temperature variation of Hc for the thinner films was found to be qualitatively similar to that found in Fe particles covered with an oxide shell
Keywords :
atomic force microscopy; coercive force; ferromagnetic materials; grain size; iron; magnetic domains; magnetic force microscopy; magnetic particles; magnetic thin films; nanostructured materials; sputtered coatings; transmission electron microscopy; 30 K; 5 nm; AFM; Al2O3; Fe; Fe films; Fe particles; TEM; atomic force microscopy; coercivity; commercial nanoporous substrates; contiguous ferro-magnetic network; domain structure; grain size; magnetic clusters; magnetic coercivity; magnetic force microscopy; magnetic microstructure; magnetic structure; morphology; nanochannel alumina; small interconnected grains; temperature dependence; transmission electron microscopy; Atomic force microscopy; Coercive force; Iron; Magnetic domains; Magnetic films; Magnetic force microscopy; Magnetic separation; Nanoporous materials; Temperature dependence; Transmission electron microscopy;
Journal_Title :
Magnetics, IEEE Transactions on