Antiferromagnetism of fcc Fe thin films

Abstract

Articles you may be interested inNonlinearities in composition dependence of structure parameters and magnetic properties of nanocrystalline fcc/bcc-mixed Co-Ni-Fe thin films Thin iron films (~18A thick and 90% enriched in Fe S7 ) were prepared on (001) Cu single-crystal substrates. The fcc structure was verified by electron microscopy. By Mossbauer spectroscopy it was found that antiferromagnetic ordering begins at around 80 ± 10K with hyperfine fields of about 16-20 kOe at 4.2 K. Additional proof for the existence of antiferromagnetism has been obtained by measuring the films in a longitudinal (parallel to the ')'-ray direction) external magnetic field. The apparent discrepancy in the literature of ferromagnetic and antiferromagnetic ordering in fcc films might be resolved by taking into account the differences concerning the film orientations.

Magnetic properties of the CrMnFeCoNi high-entropy alloy

“…The value of δ is in agreement with that for fine gamma iron, e.g. in form of precipitates in Cu rich CuFe alloys [51,52]. An important broadening of the single line can be observed at 5 K (Fig.…”

Mössbauer Study of Iron-Containing Carbon Nanotubes

“…100 K and thus it suffers an abrupt increase . The shape of the FWHM vs. T curve resembles that recorded from epitaxially evaporated y-Fe thin films sandwiched between [100] Cu layers [4] and therefore confirms the assignment of this contribution to that phase. Thus, the observed kink at 100 K in that curve would correspond to the onset of antiferromagnetic order of y-Fe.…”

Microstructure and magnetism of nanoparticles withγ-Fecore surrounded byα-Feand iron oxide shells

“…The spectrum recorded at 300 K can be satisfactorily described with three different components: ͑i͒ a well-defined sextet with B HF ͑Ϸ33.0 T͒ attributed to the ␣-Fe phase; ͑ii͒ an intense single peak with isomer shift ͑␦ ϳ −0.1 mm s −1 ͒ assigned to paramagnetic ␥-Fe phase 44,45,53 ͑note that the value of the lattice parameter at room temperature, a Ͻ3.6 Å, suggests a nonferromagnetic state for ␥-Fe͒, and ͑iii͒ a quadrupolar doublet plus a broad single line to better describe the baseline both with the same isomer shift ͑ϳ0.38 mm s −1 ͒ typical of some ferric oxide species. The relative proportions are: 43͑2͒%, 28͑2͒%, and 29͑1͒%, respectively.…”

“…Up to now, this ␥-Fe phase was observed in small iron precipitates embedded in a Cu matrix, 38 in FeCu mechanically alloyed compounds, 39,40 in the synthesis of carbon nanotubes, [41][42][43][44][45][46][47][48] or in Fe-NPs and thin films but confined down to a few monolayers of thickness. [49][50][51][52][53][54][55] The magnetism of ␥-Fe phase depends strongly on the Fe-Fe interatomic distances 56 although both the morphology of the sample and the particle size could play an important role. Indeed, AFM interactions are favored at low temperatures ͑T Ͻ 100 K͒ and for lattice parameters, a Ͻ 3.6 Å, while FM state with high Fe magnetic moment values ͑ Ͼ 2.5 B ͒ can be stabilized for a Ͼ 3.6 Å.…”