Title :
Dependence of coercivity ratio on anisotropy distribution and interactions in particulate media
Author :
Wang, S. ; Harrell, J.W.
Author_Institution :
Dept. of Phys. & Astron., Alabama Univ., Tuscaloosa, AL, USA
Abstract :
Summary form only given. The distribution of anisotropy energies is an important consideration in the performance of high-density recording media. Particles with very small anisotropy energies will be thermally unstable and particles with very large anisotropy energies may not be switchable. It was recently shown that large anisotropy distributions exist in L1/sub 0/ materials with partial chemical ordering, including FePt nanoparticles and CoPt/SiO/sub 2/ multilayer films. It was also observed that these partially ordered materials have large remanent to ordinary coercivity ratios that may be related in part to the anisotropy distribution. We have calculated the dependence of the coercivity ratio on the anisotropy distribution width and examined the effect of interactions on this dependence. The effect of both anisotropy distribution and mean field interaction parameter on the width of the irreversible susceptibility versus field curve was also calculated. These results suggest that the coercivity ratio can be a useful parameter for estimating anisotropy distribution widths in granular systems with weak interactions.
Keywords :
anisotropic media; coercive force; magnetic anisotropy; magnetic multilayers; magnetic particles; magnetic recording; magnetic susceptibility; magnetic thin films; nanoparticles; remanence; thermal stability; CoPt-SiO/sub 2/; CoPt/SiO/sub 2/ multilayer films; FePt; FePt nanoparticles; anisotropy distribution width; anisotropy energies; field curves; high-density recording media performance; irreversible susceptibility; mean field interaction parameters; media coercivity ratio dependence; partial chemical ordering L1/sub 0/ materials; particle anisotropy energy; particle switchability; particle thermal stability; particulate media anisotropy distribution; particulate media interactions; remanent/ordinary coercivity ratios; thermally unstable particles; weak interaction granular systems; Anisotropic magnetoresistance; Astronomy; Chemicals; Chromium; Coercive force; Crystallization; Iron; Magnetic properties; Nanoparticles; Physics;
Conference_Titel :
Magnetics Conference, 2002. INTERMAG Europe 2002. Digest of Technical Papers. 2002 IEEE International
Conference_Location :
Amsterdam, The Netherlands
Print_ISBN :
0-7803-7365-0
DOI :
10.1109/INTMAG.2002.1000646