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Small-angle neutron scattering study of magnetic microstructures in Co–Cr films

1998; Elsevier BV; Volume: 184; Issue: 1 Linguagem: Inglês

10.1016/s0304-8853(97)01107-4

1873-4766

Jun Suzuki, Kuniharu Takei, Yasushi Maeda, Yukio Morii,

Magnetic properties of thin films

We report a small-angle neutron scattering (SANS) study of the influence of compositional separation (CS) on the magnetic microstructure of sputtered Co–22 at% Cr thin films deposited at substrate temperatures (TS) of 40–400°C. Using vibrating sample magnetometry and nuclear magnetic resonance, we observed that CS producing a Co-enriched component develops as TS increases and becomes most prominent at around 250°C with a maximum saturation magnetization. At TS over 400°C compositional homogenization occurs. The SANS spectra show that all the films exhibit much larger scattering cross-sections than that of a compositionally homogeneous Co–22 at% Cr bulk alloy sample. This indicates that CS promotes both magnetic and chemical microstructures in the thin films. The SANS spectra are observed to change systematically with the variation in TS. An analysis of these spectra suggests that CS produces in-grain columnar magnetic microstructures with small sizes of several nanometers at TS of 40–200°C, and these microstructures become particulate at TS of 300 and 400°C, where compositional homogenization occurs. It is shown that TS is a critical factor in the formation of the magnetic microstructures.