Magnetic and electrical properties of single-phase, single-crystal Fe16N2 films epitaxially grown by molecular beam epitaxy (invited)

Abstract

The average magnetic moment per Fe atom for a single-phase, single-crystal Fe16N2(001) film epitaxially grown on a GaAs(001) substrate by molecular beam epitaxy has been confirmed to be 3.5μB at room temperature by using a vibrating sample magnetometer (VSM) and Rutherford backscattering. The value was in good agreement with that obtained by using a VSM and by measuring the film thickness (3.3μB per Fe atom). The saturation magnetization 4πMs has been found to increase with decreasing temperature, obeying T3/2 law at lower temperatures. The slope was steeper than that of a pure Fe film, suggesting a lower exchange constant for Fe16N2. The g factor for Fe16N2 has been accurately measured to be 2.17 by using ferromagnetic resonance with changing frequencies of 35.5–115 GHz, which is not unusual compared with the g factor of 2.16 for pure Fe. The resistivity for Fe16N2 has been measured to be around 30 μΩ cm at room temperature compared with 10 μΩ cm for pure Fe and decreases linearly with decreasing temperature. The behavior was that for normal metal and nothing unusual was seen. The anomalous Hall resistivity for Fe16N2 was 4×10−7 V cm/A, which is about three times as large as that for pure Fe. The relationship between the giant magnetic moment and the anomalous Hall resistivity has not been clarified yet.

Magnetic and electrical properties of iron nitride films containing both amorphous matrices and nanocrystalline grains

“…This behavior is a typical change in electrical resistivity in the metals. The electrical resistivity (15 mV cm) of the iron film is higher than that of the single crystalline iron film (around 10 mV cm) [19]. This increases in electrical resistivity is considered to be due to the electron scattering by the grain boundary because the iron film prepared in this study has a polycrystalline structure.…”

FeN foils by nitrogen ion-implantation

“…1-3 a 00 -Fe 16 N 2 is considered as a potential candidate for rare-earth-free magnets with a promising magnetic energy product performance because of its giant saturation magnetization and large magnetocrystalline anisotropy. 4 Since the discovery of a 00 -Fe 16 N 2 phase by Jack, 5 researchers have tried several fabrication methods to synthesize this phase, including MBE, 6,7 facing target sputtering, [8][9][10] reactive magnetron sputtering, 11,12 ion implantation, [13][14][15] and ion beam deposition. 16,17 However, the results based on thin film samples showed heavy discrepancies on magnetic properties.…”

First principles calculations of the magnetic properties of Fe–N systems

“…Mössbauer spectra revealed a single hyperfine field of 330 kOe for Fe 16 N 2 [4]. The g-factor for Fe 16 N 2 has been accurately measured to be 2.17 by ferromagnetic resonance, indicating that the magnetic moment originates mainly from spin [5]. However, the origin and properties of giant magnetic moments [6] remains still unclear.…”

“…Extensive work [4][5][6][7][8][9][10][11][12][13] has carried out to clarify the origin of giant magnetic moments. Mössbauer spectra revealed a single hyperfine field of 330 kOe for Fe 16 N 2 [4].…”