Enhancement of coercivity in nanometer-size CoPt crystallites

Authors

Sy_Hwang Liou, University of Nebraska-LincolnFollow
S. Huang, University of Nebraska-Lincoln
Elizabeth S. Klimek, University of Nebraska-LincolnFollow
Roger D. Kirby, University of Nebraska-LincolnFollow

Date of this Version

4-15-1999

Comments

Published in Journal of Applied Physics, 85:8 (April 15, 1999), 4334-4336. DOI: 10.1063/1.370359
Copyright © 1999 The American Institute of Physics. Used by permission.
Journal website = http://jap.aip.org/

Abstract

In this study, we showed that a magnetic coercivity (H_c) as high as 37 kOe was obtained in a CoPt thin film that contains separated nanometer-size CoPt crystallites. We prepared CoPt thin films with thicknesses of 5 and 175 nm by magnetron sputtering. After annealing in an Ar/H₂ atmosphere at temperatures from 650 to 750 °C for 3–12 h, we measured the magnetic properties and found that magnetic H_c relates to annealing temperature, annealing time and film thickness. From atomic force microscopy and magnetic force microscopy studies, the magnetic single domain size of CoPt is in the range of 100–200 nm. The high H_c is likely due to the well-separated nanometer-size crystallites and the well-ordered fct phase of CoPt alloy.