Phase formation and magnetic properties of Co-rare earth magnetic films

Authors

Yi Liu, University of Nebraska-LincolnFollow
Richard A. Thomas, University of Nebraska - Lincoln
S.S. Malhotra, University of Nebraska - Lincoln
Z.S. Shan, University of Nebraska - Lincoln
Sy_Hwang Liou, University of Nebraska-LincolnFollow
David J. Sellmyer, University of Nebraska-LincolnFollow

Date of this Version

6-1-1998

Comments

Published by American Institute of Physics. J. Appl. Phys.,83, 6244 (1998). © 1998 American Institute of Physics. Permission to use. http://jap.aip.org/jap/.

Abstract

Co–Sm and Co–Pr films were deposited by dc magnetron sputtering. Transmission electron microscopy and magnetic measurement were used to study the microstructure and magnetic property relationship. The nanostructure of the as-deposited Co 19 at. % Sm films consists of two phases: the amorphous phase and the crystallite phase. Upon annealing at 600 °C, the Co₅Sm phase with the Cu₅Ca structure, having grain size of about 20 nm, is obtained along with high coercivity (45 kOe). The as-deposited Co 22 at. % Sm films also have nanostructure similar to the Co 19 at. % films except the volume fraction of the crystallite is reduced. This is related to the concentration of Sm which promotes the formation of the amorphous phase. A new metastable phase Co₃Sm is formed upon annealing of the Co 22 at. % Sm film at 500 °C. This phase has the DO₁₉ structure in which the Sm atoms take ordered positions of a triangular pattern in the close-packed planes. A relatively high coercivity value of 29 kOe was obtained from this phase. The as-deposited Co–Pr films show mainly an amorphous phase. Upon annealing at 500 °C for 20 min, Co₂Pr with the Mg₂Cu-type structure was identified in the Co 35 at. % Pr film. Two phases were identified in the Co 16 at. % Pr films. Coercivities up to 3.1 kOe were achieved in these films.