Anomalous Hall effect (AHE) in ferrimagnetic Mn 4 N epitaxial films grown by molecular-beam epitaxy is investigated. The longitudinal conductivity r xx is within the superclean regime, indicating Mn 4 N is a highly conducting material. We further demonstrate that the AHE signal in 40-nmthick films is mainly due to the extrinsic contributions based on the analysis fitted by q AH ¼ a 0 q xx0 þ bq 2 xx and r AH / r xx . Our study not only provide a strategy for further theoretical work on antiperovskite manganese nitrides but also shed promising light on utilizing their extrinsic AHE to fabricate spintronic devices. V C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4906420] Implementing spin functionality in semiconductor is vital to establish a spin-based electronics with potential to change information technology beyond imagination. 1 In order to create and control of spin polarization, realization of the inter-conversion between spin current and charge current is essential. 2,3 Such inter-conversion could be achieved either by the intrinsic mechanism or by the extrinsic mechanisms in the anomalous Hall effect (AHE). 4 The intrinsic AHE (q AH / q 2 xx ) arises from the band structure effects, 5 while the two basic extrinsic mechanisms leading to AHE are skew scattering 6 (q AH / q xx ) and side-jump 7 (q AH / q 2 xx ) due to the spin-obit interaction (SOI) acting on a conduction band electron. Accordingly, a conventional scaling law q AH ¼ aq xx þ bq 2 xx is widely used to distinguish the various contributions to the AHE.Notably, recent studies in Fe and Co films demonstrated a proper scaling of q AH ¼ a 0 q xx0 þ bq 2 xx (q xx0 is the residual resistivity), 8,9 which excluded the contribution of phonon skew scattering and emphasized the extrinsic contributions of skew scattering and side-jump from impurities. Moreover, based on plenty of experimental results and theoretical calculations, three scaling regimes for the AHE has been proposed as a function of the longitudinal conductivity r xx . 10-12 (i) In the poorly conducting regime (r xx < 3 Â 10 3 X À1 cm À1 ), there exists a universal scaling relation of r AH / r 1:6 xx ; (ii) in the moderately dirty regime (3 Â 10 3 X À1 cm À1 < r xx < 5 Â10 5 X À1 cm À1 ), the r AH stays roughly constant and intrinsic contribution dominates; and (iii) in the superclean regime with r xx > 5 Â 10 5 X À1 cm À1 , where r AH / r xx , the AHE behavior depends on the properties of dilute impurities embedded in the materials. The clarification of the interplay between the different contributions of the AHE is of fundamental importance for the better understanding of this phenomenon, and also seems particularly promising in the prospect of novel applications at room temperature and above.e-phase ferrimagnetic Mn 4 N is a reservoir of functionalities due to the great variety of its advantageous properties including perpendicular magnetic anisotropy, 13 zero thermal expansion, 14 and spin-glass behavior. 15 Recently, an experimental work 16 on Mn 4 N, focusing on the AHE at roo...

Topological Hall effect (THE) as one of spin-related effects originates from scalar spin chirality formed by non-coplanar spin structures, being a promising tool for probing the change of electron spin. Single-phase (022) Mn4N films with coplanar spin structures were prepared on unpoled ferroelectric [Pb(Mg1/3Nb2/3)O3]0.67-[PbTiO3]0.33 (PMN-PT) substrates. The transport properties of Mn4N/PMN-PT have been investigated. The decreased magnetization and anomalous resistivity imply that the spin states of Mn4N are influenced by ferroelectric polarization of the substrate. The observation of THE in the Mn4N/PMN-PT heterostructure strongly supports that the spin states of Mn4N are modified. After poling PMN-PT, the enhanced THE peak magnitude verifies that the spin states of Mn4N are tuned by ferroelectric polarization. This study provides a non-magnetic method for manipulation of spin states, which could avoid the external magnetic field perturbations.

Growth and magnetic property of antiperovskite manganese nitride films doped with Cu by molecular beam epitaxy J. Appl. Phys. 115, 133911 (2014); 10.1063/1.4870579 Above room-temperature ferromagnetism of Mn delta-doped GaN nanorods Appl. Phys. Lett. 104, 062414 (2014); 10.1063/1.4865785 Room-temperature ferromagnetism in (Mn, N)-codoped TiO 2 films grown by plasma assisted molecular beam epitaxy J. Appl. Phys.Single-phase and oxygen doped Mn 2 N 0.86 thin films have been grown on MgO (111) by plasmaassisted molecular beam epitaxy. The films grow under tensile strain and, remarkably, they show ferromagnetic-like interactions at low temperature and ferromagnetic ordering agreed well with the Bloch-law T 3/2 at room-temperature. We further demonstrate the enlarged Mn 3s splitting (6.46 eV) and its possible relation to the observed ferromagnetism. Our study not only provide a strategy for further theoretical work on oxygen doped manganese nitrides, but also shed promising light on utilizing its room-temperature FM property to fabricate spintronic devices. V C 2014 AIP Publishing LLC. [http://dx.

Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn4−xDyxN films grown by molecular-beam epitaxy. The introduction of Dy changes the AHE dramatically, even changes its sign, while the variations in magnetization are negligible. Two sign reversals of the AHE (negative-positive-negative) are ascribed to the variation of charge carriers as a result of Fermi surface reconstruction. We further demonstrate that the AHE current JAH is dissipationless (independent of the scattering rate), by confirming that anomalous Hall conductivity, σAH, is proportional to the carrier density n at 5 K. Our study may provide a route to further utilize antiperovskite manganese nitrides in spintronics.

The anomalous Hall effect (AHE) in the Mn4N/Au bilayers with various Au thicknesses has been investigated. The new scaling including multiple competing mechanisms is employed to analyze the contributions to the AHE. The obvious variations in the skew scattering coefficient α and the two scattering coefficients (β0 + β1 − γ) and (γ − 2β1) in the bilayers reveal that the skew scattering term and the side-jump contribution are dramatically modified, implying that the mechanisms in the bilayers are different from those in the single Mn4N. On further analysis, we find that the coefficient β0 involving the intrinsic mechanism and side-jump contribution also varies, which confirms the experimental results. It is proposed that the modification of the AHE is induced by the spin-orbital coupling from the heavy metal, providing a practical way to tune the AHE.

The magnetic properties and anomalous Hall effect of the Mn4N (002) film mixed with the (111) phase were investigated. The lessened magnetization of hysteresis loops at a low field and the peak at about 50 K of the temperature-dependent magnetization curves display that magnetocrystalline anisotropies play a significant role in the magnetic properties of the film. Moreover, the centres of the anomalous Hall loops are shifted to the left for positive currents and show the opposite shift for negative currents, which may indicate the presence of current-induced effective fields. It is proposed that the (111) phase in the film could not only supply the magnetization m derivation from the c aixs but also afford asymmetric interfaces to induce effective fields. The effective perpendicular field arises from the perpendicular components of the effective fields.

No abstract

No abstract