Magnetic and physical microstructure of Fe{sub 16}N{sub 2} films grown epitaxially on Si(001)
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
- Department of Physics, Shiga University of Medical Science, Seta, Otsu, 520-21 Shiga (Japan)
Epitaxial Fe{sub 16}N{sub 2} films were grown on Si(001) substrates with an Ag underlayer by reactive sputtering in nitrogen. Pure {alpha}{sup {prime}}-Fe{sub 8}N films were obtained which on subsequent annealing resulted in mixtures of {alpha}{sup {prime}}-Fe{sub 8}N (54{percent}) and {alpha}{sup {prime}{prime}}-Fe{sub 16}N{sub 2} (46{percent}). An average moment of 1780 emu/cc, considerably larger than that of pure {alpha}-Fe (1714 emu/cc), was measured for both samples. Plan-view transmission electron microscopy of the films confirms the orientation relationship Fe{sub 16}N{sub 2}(001){parallel}Ag(001){parallel}Si(001) and Fe{sub 16}N{sub 2}[100]{parallel}Ag[110]{parallel}Si[100], and a small grain size ({approximately}100 {Angstrom}), while electron energy-loss spectroscopy confirms an average composition of Fe{sub 8}N for both samples. Electron diffraction patterns indicate that the as-deposited {alpha}{sup {prime}} films already contain very small regions of ordered {alpha}{sup {prime}{prime}} which were not previously detected by x-ray diffraction measurements. M{umlt o}ssbauer spectroscopy performed at both 300 and 16 K gave three hyperfine fields corresponding to three different iron sites for both the unannealed {alpha}{sup {prime}} and the annealed {alpha}{sup {prime}}/{alpha}{sup {prime}{prime}} mixtures. Lorentzian fitting of the three iron components for the {alpha}{sup {prime}}/{alpha}{sup {prime}{prime}} spectrum obtained at room temperature gave an intensity ratio of 1:2:1 (FeI:FeII:FeIII) corresponding to the expected occupancy for the three Fe sites in the Fe{sub 16}N{sub 2} structure. Moreover, the pure {alpha}{sup {prime}} film at 300 K and both samples at 16 K showed deviation from this distribution. The three components show notable differences in the temperature dependence of their occupancies; however, all three magnetic components deviate similarly from the surface normal. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 496433
- Report Number(s):
- CONF-961141-; ISSN 0021-8979; TRN: 97:016134
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 8; Conference: 41. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 12-15 Nov 1996; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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