Stability and magnetic properties of cobalt nitrides

Lourenço, M.B.; Carvalho, Maria Graça; Fonseca, P. T.; Gasche, T.; Evans, G.; Godinho, M.; Cruz, M.M.

doi:10.1016/j.jallcom.2014.05.048

Cited by 32 publications

(37 citation statements)

References 27 publications

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“…The stoichiometry of the cubic nitride can then be obtained from the films CoN10, considering the one with lower nitrogen content, where less nitrogen segregation or none is expected. This is Co 16 N, that agrees with the reported stoichiometry of the cubic nitride Co 4+x N with higher nitrogen content produced by nitriding cobalt particles [12].…”

Section: Resultssupporting

confidence: 89%

“…In the ferromagnetic phases the moment per iron or cobalt decreases with the increase of the nitrogen content [11], the cubic phases displaying the highest magnetizations. Experimental reported values for Fe 4 N and Co 4+x N saturation magnetizations at room temperature are 210 A m 2 kg −1 [8] and 143 A m 2 kg −1 [12] respectively. In thin films the coercivity is higher in nitride films than in the cobalt films and remains almost constant for different nitrogen content [3,13].…”

Section: Introductionmentioning

confidence: 95%

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Influence of the substrate on structure and magnetic properties of Co–N thin films

Silva

Vovk

Silva

et al. 2015

Journal of Alloys and Compounds

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 95%

Influence of the substrate on structure and magnetic properties of Co–N thin films

Silva

Vovk

Silva

et al. 2015

Journal of Alloys and Compounds

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“…Therefore, our observation that independent of R N 2 (at T s = 523 K) used, the phases form are always similar, is surprising and such behavior has not been seen before for the Co-N system. On the other hand a lot of experimental reports are available, claiming the formation of Co 4 N phase at T s varying from 433 K to 723 K [25,3,5,24,6]. Use of such higher T s might have been influenced by Fe 4 N phase which is generally formed at T s ∼673 K.…”

Section: Discussionmentioning

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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“…[11][12][13][14][15][16][17][18][19] Recent theoretical calculations predicted that the spin polarization ratio for Co 4 N is even higher than that of Fe 4 N. 20,21 This has led to somewhat renowned interests in the Co-N system both theoretically and experimentally. [22][23][24][25][26][27][28] Though theoretical studies predict that under large-volume high-moment approach, the magnetic moment of Co 4 N can be larger than Co, 9 experimental results always find a value much smaller than pure Co, for Co 4 N thin films. 22 This can be understood as in all Co 4 N thin films reported so far the value of a has always been smaller than the value predicated theoretically.…”

Section: Introductionmentioning

confidence: 99%

Phase formation, thermal stability and magnetic moment of cobalt nitride thin films

et al. 2015

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Cobalt nitride (Co-N) thin films prepared using a reactive magnetron sputtering process are studied in this work. During the thin film deposition process, the relative nitrogen gas flow (RN2) was varied. As RN2 increases, Co(N), Co4N, Co3N and CoN phases are formed. An incremental increase in RN2, after emergence of Co4N phase at RN2 = 10%, results in a linear increase of the lattice constant (a) of Co4N. For RN2 = 30%, a maximizes and becomes comparable to its theoretical value. An expansion in a of Co4N, results in an enhancement of the magnetic moment, to the extent that it becomes even larger than pure Co. Such larger than pure metal magnetic moment for tetra-metal nitrides (M4N) have been theoretically predicted. Incorporation of N atoms in M4N configuration results in an expansion of a (relative to pure metal) and enhances the itinerary of conduction band electrons leading to larger than pure metal magnetic moment for M4N compounds. Though a higher (than pure Fe) magnetic moment for Fe4N thin films has been evidenced experimentally, higher (than pure Co) magnetic moment is evidenced in this work.

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Stability and magnetic properties of cobalt nitrides

Cited by 32 publications

References 27 publications

Influence of the substrate on structure and magnetic properties of Co–N thin films

Influence of the substrate on structure and magnetic properties of Co–N thin films

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

Phase formation, thermal stability and magnetic moment of cobalt nitride thin films

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