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 · Sat Nov 30 23:00:00 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), Journal Name: Scripta Metallurgica; (United States) Vol. 25:12; ISSN 0036-9748; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

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