Magnetic and structural characterizations of copper/chromium and iron/molybdenum multilayered thin films
Several series of Cu/Cr and Fe/Mo multilayered structures (MLS) have been grown by ultrahigh-vacuum electron-beam evaporation on oxidized Si substrates. Structural characterizations by small-angle x-ray scattering (SAXS) and large-angle x-ray scattering (LAXS) have been carried out on Cu/Cr MLS. While the MLS with nominal bilayer periods as low as 28 {angstrom} exhibit layered structure, essentially no composition modulation is evident in 10 {angstrom} bilayer thickness films. For such films, up to {approximately} 40% Cr is found to dissolve in bcc Cr to form a supersaturated solid solution. Magnetic, magnetotransport, and structural characterizations have been carried out on Fe/Mo MLS. For Fe(30{angstrom})/Mo(t{sub Mo}{angstrom}) MLS in which the Mo layer thickness t{sub Mo} is varied from 7 {angstrom} to 25 {angstrom}, hysteresis loop computer fits showed that the saturation field - which measures antiferromagnetic (AF) coupling strength A - oscillates. The maximum A is {approximately} 0.47 ergs/cm{sup 2} for t{sub Mo} = 11 {angstrom}, and slightly less than one oscillation has been observed. The low-temperature magnetoresistance (MR) oscillates similarly and attains a maximum of {approximately} 2%. Several Fe(30{angstrom})/Mo(11{angstrom}) MLS have been prepared at substrate temperatures T{sub s} ranging from 150-475 K in order to systematically alter the structural properties. Low T{sub s} samples have the largest change in resistivity upon magnetic saturation, although A and MR are largest for the 300 K sample. SAXS, LAXS, and high-resolution electron microscopy reveal a high degree of structural disorder. Low T{sub s} samples degenerate into a heterogeneous alloy of small crystallites beyond {approximately} 4-5 bilayers, while high T{sub s} samples contain much larger crystallites but exhibit extreme propagating roughness beyond the first bilayer. The layering is most nearly intact for the 300 K sample.
- Research Organization:
- Arizona State Univ., Tempe, AZ (United States)
- OSTI ID:
- 111250
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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