The Enhancement of Magnetic Damping in Fe₄N Films with Increasing Thickness

Abstract

The film thickness dependence of the magnetic damping coefficient (α) was investigated by measuring the ferromagnetic resonance (FMR) of Fe4N/NM (NM: Pt and Cu) bilayer films at room temperature. We observed that α in Fe4N/Pt films increased with increasing Fe4N film thickness. Moreover, the enhancement of α, which is represented by the difference in the α values of Fe4N/Pt and Fe4N/Cu films, also increased as the Fe4N film thickness increased. The behavior observed in the Fe4N system was the opposite of that observed for the conventional Ni–Fe system. We speculated two mechanisms occurring in Fe4N/Pt films, which are less magnetic and/or nonmagnetic impurities in the Fe4N films and enhancement of the coercive force (H c) with increasing Fe4N film thickness.

Deposition and spin polarization study of Fe4N thin films with (111) orientation

“…This result is similar to the M s of Fe 4 N thin films reported by several other experimental works. 10,11,15 It is also consistent with our previous experiment result of Fe 4 N. 19 The M s of Fe 4 N obtained in this work shows smaller value than the theoretical calculation results that are in a range of 2.1-2.45 µ B /Fe atom [20][21][22] (1410-1650 emu/cm 3 ) at zero temperature (0K). We attribute the smaller M s of Fe 4 N thin films in our experiment to the thermal excitation on magnetization as well as the defects and grain boundaries of the thin film sample.…”

“…13 To improve its flexibility for applications, it is also of interest to deposit Fe 4 N on the non-magnetic metal buffer layers rather than single crystal substrates, as the metal layers underneath Fe 4 N may facilitate a variety of spintronics devices. 3,4,14,15 In addition, the spin polarization of a material is closely related to its growth conditions and crystallinity. Therefore, studying the spin a Author to whom correspondence should be addressed: jpwang@umn.edu 2158-3226/2017/7(9)/095001/6 7, 095001-1 © Author(s) 2017 polarization of Fe 4 N grown on a practical metal buffer layer is also very helpful for its applications in spintronics.…”

Antiperovskite Magnetic Materials with 2p Light Elements for Future Practical Applications

“…[53] The damping constant of the Fe 4 N/Pt bilayer structure has been measured to range from 0.02 to 0.03, which is dependent on the film thickness of the Fe 4 N layer. [155][156][157] Exploring the influence of these characteristics on spin pumping has led us to design suitable materials for enhanced spin pumping efficiency.…”

Dependence of Magnetic Damping on Temperature and Crystal Orientation in Epitaxial Fe4N Thin Films

“…In prior research on out-of-plane FMR in Ni-Fe, Co-Fe-B, Co2MnSi, and even poly-crystalline Fe4N, the whole H was successfully fitted by calculation. 6,18,[23][24][25][26] Even though the mechanism is not yet fully identified, judging from the fact that the unmatched fitting result appears stronger for H = 45 deg., domain structures in small H are considered as a possible mechanism because of K1 in the epitaxial Fe4N film. Such an additional resonance has been presumed to be domain structure excitation below magnetic saturation in crystals with strong magnetic anisotropy.…”

“…We investigated  of "poly"-crystalline Fe4N films in a previous study. 18) In contrast, epitaxial Fe4N films, considered an important spintronics material for the future, excited our curiosity based on how its magnetocrystalline anisotropy acts upon anisotropic .…”