Anisotropic magnetoresistance in facing-target reactively sputtered epitaxial γ′-Fe4N films

Li, Z.R.; Feng, X.P.; Wang, X.C.; Mi, Wenbo

doi:10.1016/j.materresbull.2015.01.053

Cited by 39 publications

(33 citation statements)

References 33 publications

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“…In accordance with this expression, the fact that the minority spins dominate the electrical conductivity in Fe 4 N was confirmed by the negative r AMR . [10][11][12][13][14][15] In the same manner, the negative r AMR in Co 3 FeN indicates that the minority-spin electrons determine the electrical conductivity.…”

Section: Introductionmentioning

confidence: 84%

“…2 It is considered that the inverse TMR effect and inverse current-induced magnetization switching effect in Fe 4 N/MgO/CoFeB magnetic tunnel junctions are caused by the minority spin transport in Fe 4 N. [3][4][5][6] Recently, several studies on magnetotransport properties in ferromagnetic materials such as anisotropic magnetoresistance (AMR) effect have been conducted theoretically [7][8][9] and experimentally. [10][11][12][13][14][15][16][17][18][19][20] Kokado et al derived a general expression of the AMR ratio r AMR from the two-current model, which consists of a spin-polarized conduction state and localized d states with spin-orbit interaction (SOI). They used a resistivity of the conduction state and resistivities due to s-d scattering processes from the conduction state to the localized d states, and expressed r AMR as…”

Section: Introductionmentioning

confidence: 99%

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Negative anisotropic magnetoresistance resulting from minority spin transport in NixFe4−xN (x = 1 and 3) epitaxial films

Takata

Kabara

Ito

et al. 2017

Journal of Applied Physics

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We grew 50 nm-thick NixFe4−xN (x = 1 and 3) epitaxial films on a SrTiO3(001) single-crystal substrate by molecular beam epitaxy and measured their anisotropic magnetoresistance (AMR) ratios rAMR in the temperature range of 5–300 K with current directions set along either NixFe4−xN [100] or [110]. A negative rAMR was obtained up to 200 K or higher. Their magnitude |rAMR| increased with decreasing temperature. From the negative AMR effect and the negative spin-polarization of density of states for NixFe4−xN at the Fermi level, it can be stated that the minority spin transport is dominant in NixFe4−xN, similar to Fe4N and Co3FeN. The rAMR depends on the current direction that arises from the current direction dependence of s-d scattering. In the case of Ni3FeN, the rAMR decreased to nearly zero at 260 K. This temperature agreed well with the Curie temperature determined from the temperature dependence of magnetization. The AMR curves were reproduced well by using both cos2ϕ and cos4ϕ components below 100 K, whereas a cos2ϕ component was enough to fit those obtained above 100 K. It is assumed that the tetragonal crystal field was enhanced at low temperatures (<100 K) similar to Fe4N (<50 K).

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Negative anisotropic magnetoresistance resulting from minority spin transport in NixFe4−xN (x = 1 and 3) epitaxial films

Takata

Kabara

Ito

et al. 2017

Journal of Applied Physics

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“…A lot of theoretical [11,12,13,14,15] and experimental [16,17,18,19,20,21,22,23] reports are available on iron nitride (Fe-N) system. In a number of studies Fe 4 N thin films have been prepared and studied [16,17,18,19,20,21,22,23]. On the other hand, the Co-N system has not been explored as much.…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of Co-N thin films deposited using magnetron sputtering at 523 K

Pandey

Gupta

et al. 2017

Journal of Alloys and Compounds

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In this work, we studied cobalt nitride (Co-N) thin films deposited using a dc magnetron sputtering method at a substrate temperature (T s ) of 523 K. We find that independent of the reactive gas flow (R N 2 ) used during sputtering, the phases of Co-N formed at this temperature seems to be identical having N at.% ∼5. This is contrary to Co-N phases formed at lower T s . For T s ∼300 K, an evolution of Co-N phases starting from Co(N)→Co 4 N→Co 3 N→CoN can be seen as R N 2 increases to 100%, whereas when the substrate temperature increases to 523 K, the phase formed is a mixture of Co and Co 4 N, independent of the R N 2 used during sputtering. We used x-ray diffraction (XRD) to probe long range ordering, x-ray absorption spectroscopy (XAS) at Co absorption edge for the local structure, Magneto-optical Kerr e ffect (MOKE) and polarized neutron reflectivity (PNR) to measure the magnetization of samples. Quantification of N at.% was done using secondary ion mass spectroscopy (SIMS). Measurements suggest that the magnetic moment of Co-N samples deposited at 523 K is slightly higher than the bulk Co moment and does not get affected with the R N 2 used for reactive sputtering. Our results provide an important insight about the phase formation of Co-N thin films which is discussed in this work.

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“…1 Extensive studies have been performed on the magnetic and transport properties of Fe 4 N after this report. [2][3][4][5][6][7][8][9][10][11][12] The spin polarization of Fe 4 N has been experimentally confirmed by point contact Andreev reflection (PCAR) on a (100) oriented Fe 4 N thin film. 2 Magnetic tunnel junctions (MTJ) with Fe 4 N ferromagnetic electrodes has been reported and their MR ratios are as large as 75% at room temperature.…”

Section: Introductionmentioning

confidence: 99%

“…8,9 To date, most of the spintronics related studies on Fe 4 N are based on epitaxial or polycrystalline thin films with (100) out-of-plane orientation. 2, [10][11][12] It is worthwhile to explore Fe 4 N films with other orientations for the purpose of multilayer stack integration. For example, the (111) crystal plane is preferred by the exchange bias materials for tunneling/giant magnetoresistive (TMR/GMR) devices.…”

Section: Introductionmentioning

confidence: 99%

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

Osofsky

Jensen

et al. 2017

AIP Advances

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We have successfully deposited Fe4N thin films with (111) out-of-plane orientation on thermally oxidized Si substrates using a facing-target-sputtering system. A Ta/Ru composite buffer layer was adopted to improve the (111) orientation of the Fe4N thin films. The N2 partial pressure and substrate temperature during sputtering were optimized to promote the formation of the Fe4N phase. Furthermore, we measured the transport spin polarization of (111) oriented Fe4N by the point contact Andreev reflection (PCAR) technique. The spin polarization ratio was determined to be 0.50 using a modified BTK model. The film thickness dependence of the spin polarization was also investigated. The spin polarization of Fe4N measured by PCAR does not show degradation as the sample thickness was reduced to 10nm.

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Anisotropic magnetoresistance in facing-target reactively sputtered epitaxial γ′-Fe4N films

Cited by 39 publications

References 33 publications

Negative anisotropic magnetoresistance resulting from minority spin transport in NixFe4−xN (x = 1 and 3) epitaxial films

Negative anisotropic magnetoresistance resulting from minority spin transport in NixFe4−xN (x = 1 and 3) epitaxial films

Structural and magnetic properties of Co-N thin films deposited using magnetron sputtering at 523 K

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

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