Microstructure and magnetic anisotropy of ultrathin Co/Pt multilayers grown on GaAs ( 1 1 1 ) by molecular-beam epitaxy

Journal Article · Tue Dec 15 00:00:00 EST 1992 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.351934· OSTI ID:7229301

Cho, N; Krishnan, K M; Lucas, C A ^[1]; Farrow, R F.C. ^[2]

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1. National Center for Electron Microscopy, Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)
2. IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States)

Multilayers of (Co{sub 3 A}, Pt{sub 15 A}){sub {ital x}}, {ital x}=15 or 30 repeats, with or without a 200 A silver buffer layer, were grown on GaAs (111) substrates by molecular-beam epitaxy. Vibrating sample magnetometry measurements confirmed that the samples with the Ag buffer layer show strong uniaxial magnetic anisotropy perpendicular to the surface. The perpendicular anisotropy exhibited by these metallic superlattices is discussed in terms of the microstructure of the overall multilayer stack, as well as the structural characteristics of the Co interface layer. Samples grown on the Ag buffer layer show strong (111) texture with 30--40-nm-size twin-related grains. These grains, correspond to the two possible (111) stacking sequence for an fcc lattice, i.e., double positioning. However, direct growth on GaAs (111) results in randomly oriented 10--20 nm grains. All samples exhibit a repeat period of 1.83 nm in both low-angle reflectivity and high-angle {Theta}--2{Theta} x-ray scattering measurements. In addition, transverse scans through the low-angle multilayer Bragg peaks show the interfaces to be diffuse in nature indicative of considerable in-plane inhomogeneity and/or compound formation. High-resolution electron microscopy measurements of cross sections compared with image simulations confirm that the interface layer is diffuse and its stoichiometry is such that the Co occupation is less than 40%. Redistribution of Co should then extend over at least four monolayers. The nanostructure of the samples grown with the Ag buffer layer comprises an eight atomic layer repeat with the Co interface layer diffuse over four monolayers. The microstructure is strongly (111) textured with columns of twin related 30-nm-sized grains.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7229301
• Journal Information: Journal of Applied Physics; (United States), Vol. 72:12; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT
MICROSTRUCTURE
PLATINUM
ELECTRON MICROSCOPY
MAGNETIC PROPERTIES
MOLECULAR BEAM EPITAXY
THIN FILMS
X-RAY DIFFRACTION
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELEMENTS
EPITAXY
FILMS
METALS
MICROSCOPY
PHYSICAL PROPERTIES
PLATINUM METALS
SCATTERING
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties