Characterization of epitaxial sputtered Ni sub x Co sub 1 minus x O thin films on. alpha. -Al sub 2 O sub 3 using transmission electron microscopy

Journal Article · Sun Dec 01 00:00:00 EST 1991 · Scripta Metallurgica; (United States)

OSTI ID:5332604

Cao, W; Thomas, G ^[1]; Carey, M J; Berkowitz, A E ^[2]

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1. Lawrence Berkely Lab., Berkeley, CA (US)
2. Dept. of Physics and Center for Magnetic Recording Research, Univ. of California, San Diego, CA (US)

Epitaxial CoO-NiO multilayers have been produced which show interesting structural and magnetic properties. The single Neel temperature observed for {l angle}111{r angle} oxide multilayers grown on {alpha}-Al{sub 2}O{sub 3} together with similar results found for FeF{sub 2}-CoF{sub 2} multilayers, suggest that the magnetic properties of different ionic antiferromagnets can be mixed through alloying. This prompted the current study to produce Ni{sub x}Co{sub 1{minus}x}O thin films in order to study their magnetic properties. The structure of these films is discussed in this paper. Epitaxial films of NiO and CoO have been produced on {alpha}-Al{sub 2}O{sub 3} by some of the authors and others. High quality {l angle}111{r angle} films were produced by reactive sputtering and reactive evaporation confirming the epitaxial growth of the cubic monoxides on the rhombohedral (hexagonal) {alpha}-Al{sub 2}O{sub 3}. However, it was found that the monoxide films consisted of columnar grains epitaxial with the substrate, but adjacent grains related by a 60{degrees} rotation twin relationship. The exact cause of the twinning was unclear. In this respect, the twinning is found to result from the order which {l angle}111{r angle} planes of the cubic monoxide stack on the surface of the hexagonal {alpha}-Al{sub 2}O{sub 3}. Typically, epitaxial films are grown either by chemical vapor deposition or evaporation. However, sputtering can also yield high quality epitaxial layers, often at reduced substrate temperatures. Reductions in substrate temperature can be advantageous. NiO-CoO solid solutions have been shown to phase segregate at high temperatures. Also, reactions at the film-substrate interface are undesirable. Thus, sputter deposition was chosen for the production of the films discussed in this research.

• OSTI ID: 5332604
• Journal Information: Scripta Metallurgica; (United States), Vol. 25:12; ISSN 0036-9748
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
74 ATOMIC AND MOLECULAR PHYSICS
COBALT OXIDES
MAGNETIC PROPERTIES
NICKEL OXIDES
THIN FILMS
SPUTTERING
TRANSMISSION ELECTRON MICROSCOPY
ALUMINIUM OXIDES
ANTIFERROMAGNETISM
CHEMICAL REACTION KINETICS
CHEMICAL VAPOR DEPOSITION
EPITAXY
INTERFACES
PHASE DIAGRAMS
SOLID SOLUTIONS
SUBSTRATES
TEMPERATURE DEPENDENCE
TWINNING
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL COATING
COBALT COMPOUNDS
DEPOSITION
DIAGRAMS
DISPERSIONS
ELECTRON MICROSCOPY
FILMS
KINETICS
MAGNETISM
MICROSCOPY
MIXTURES
NICKEL COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
SOLUTIONS
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360201 - Ceramics
Cermets
& Refractories- Preparation & Fabrication
360204 - Ceramics
Cermets
& Refractories- Physical Properties
664400 - Experimentally Derived Information on Atomic & Molecular Properties- (1992-)