Microstructure investigations of hcp phase CoPt thin films with high coercivity

Journal Article · Fri Feb 28 04:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4866817· OSTI ID:22277981

Yang, Y.; Varghese, B.; Tan, H. K.; Wong, S. K.

CoPt films have been grown in the past with a high anisotropy in L1{sub 1} or L1{sub 0} phase, and a high coercivity is observed only in L1{sub 0} CoPt films. Recently, we have grown CoPt films which exhibited a high coercivity without exhibiting an ordered phase. In this study, high resolution transmission electron microscopy (HRTEM) investigations have been carried out to understand the strong thickness and deposition pressure dependent magnetic properties. HRTEM studies revealed the formation of an initial growth layer in a metastable hexagonal (hcp) CoPt with high anisotropy. This phase is believed to be aided by the heteroepitaxial growth on Ru as well as the formation of Ru-doped CoPt phase. As the films grew thicker, transformation from hcp phase to an energetically favourable face-centered cubic (fcc) phase was observed. Stacking faults were found predominantly at the hcp-fcc transformation region of the CoPt film. The higher coercivity of thinner CoPt film is attributed to relatively less fcc fraction, less stacking faults, and to the isolated grain structure of these films compared to the thicker films.

• OSTI ID: 22277981
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
COBALT ALLOYS
COERCIVE FORCE
COMPARATIVE EVALUATIONS
CRYSTAL GROWTH
DOPED MATERIALS
FCC LATTICES
HCP LATTICES
INTERMETALLIC COMPOUNDS
LAYERS
MAGNETIC PROPERTIES
MICROSTRUCTURE
PLATINUM ALLOYS
PRESSURE DEPENDENCE
RUTHENIUM ALLOYS
STACKING FAULTS
THICKNESS
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY