Title :
Magnetic clusters, intergranular exchange interaction and their microstructural basis in thin film longitudinal media
Author :
Tang, K. ; Schabes, M.E. ; Ross, C.A. ; He, L. ; Ranjan, R. ; Yamashita, T. ; Sinclair, R.
Author_Institution :
Dept. of Mater. Sci. & Eng., Stanford Univ., CA, USA
fDate :
9/1/1997 12:00:00 AM
Abstract :
We have experimental examined the micromagnetic structure in CoCrTa/Cr films deposited onto NiP/Al substrates at 25, 100, 150 200 and 250°C. We prepared all the films in an ac-erased magnetic state. The Lorentz transmission electron microscopy images demonstrate a monotonic decrease of magnetic cluster size with increase of deposition temperature and the magnetic force microscopy results show a decrease of image contrast. This indicates a decrease of intergranular exchange coupling with increase of deposition temperature. Nanoprobe energy dispersive spectroscopy (EDS) reveals an increase of Cr segregation at CoCrTa grain boundaries with increase of deposition temperature. The correlation of micromagnetic and microcompositional observation supports that Cr segregation at grain boundaries is responsible for decoupling CoCrTa grains. Our nanoprobe EDS results also indicate that the Cr diffuses to the grain boundaries from the diffusion process involving the Cr underlayer
Keywords :
X-ray chemical analysis; chromium alloys; cobalt alloys; coercive force; exchange interactions (electron); ferromagnetic materials; grain boundary diffusion; grain boundary segregation; magnetic force microscopy; magnetic recording; magnetic structure; magnetic thin films; sputtered coatings; tantalum alloys; transmission electron microscopy; 25 to 250 C; CoCrTa grain boundaries; CoCrTa grain decoupling; CoCrTa-Cr; CoCrTa/Cr films; Cr segregation; Lorentz transmission electron microscopy images; NiP; NiP-Al; NiP/Al substrates; ac-erased magnetic state; coercivity; deposition temperature; diffusion process; image contrast; intergranular exchange interaction; magnetic clusters; magnetic force microscopy; microcompositional observation; micromagnetic structure; nanoprobe energy dispersive spectroscopy; thin film longitudinal media; Chromium; Couplings; Elementary particle exchange interactions; Grain boundaries; Magnetic films; Magnetic force microscopy; Magnetic forces; Micromagnetics; Temperature; Transmission electron microscopy;
Journal_Title :
Magnetics, IEEE Transactions on
