Effect of dopants on thermal stability and self-diffusion in iron-nitride thin films

Surface and Coatings Technology

et al. 2015

Self Cite

In this work, we studied phase formation, structural and magnetic properties of iron-nitride (Fe-N) thin films deposited using high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (dc-MS). The nitrogen partial pressure during deposition was systematically varied both in HiPIMS and dc-MS. Resulting Fe-N films were characterized for their microstructure, magnetic properties and nitrogen concentration. We found that HiPIMS deposited Fe-N films show a globular nanocrystalline microstructure and improved soft magnetic properties. In addition, it was found that the nitrogen reactivity impedes in HiPIMS as compared to dc-MS. Obtained results can be understood in terms of distinct plasma properties of HiPIMS.

Section: Resultsmentioning

confidence: 99%

“…It is well known that transition metal magnetic nitrides are an important class of materials for their usage in various technological applications. [22,23] Therefore, it will be immensely useful to study magnetic nitride films using HiPIMS.…”

Section: Introductionmentioning

confidence: 99%

Study of magnetic iron nitride thin films deposited by high power impulse magnetron sputtering

Tayal

Surface and Coatings Technology

et al. 2015

Self Cite

“…Therefore, periodic isotope multilayer are widely used to study atomic selfdiffusion using NR. 15,32,34,[50][51][52] Figure 3 After annealing the intensity of Bragg peak start to decay and such decay is more rapid for sample (N1) than for (N2). A decay of Bragg peak intensity is a measure of atomic diffusion across interfaces.…”

Section: B Self-diffusion Measurementsmentioning

confidence: 99%

Origin of anomalous diffusion in iron mononitride thin films

Tayal

et al. 2015

Phys. Rev. B

Self Cite

We have studied the origin of a counter intuitive diffusion behavior of Fe and N atoms in a iron mononitride (FeN) thin film. It was observed that in-spite of a larger atomic size, Fe tend to diffuse more rapidly than smaller N atoms. This only happens in the N-rich region of Fe-N phase diagram, in the N-poor regions, N diffusion coefficient is orders of magnitude larger than Fe. Detailed selfdiffusion measurements performed in FeN thin films reveal that the diffusion mechanism of Fe and N is different -Fe atoms diffuse through a complex process, which in addition to a volume diffusion, pre-dominantly controlled by a fast grain boundary diffusion. On the other hand N atoms diffuse through a classical volume-type diffusion process. Observed results have been explained in terms of stronger Fe-N (than Fe-Fe) bonds generally predicted theoretically for mononitride compositions of transition metals.

“…Though the T c of Co 4 N is quite high at 827 K, its poor thermal stability is a concern. It can be anticipated that by using suitable dopants, the thermal stability of Co 4 N can be improved following a similar approach achieved in Fe-X-N [32].…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of stoichiometric Co4N epitaxial thin films

Pandey

et al. 2019

Phys. Rev. B

Self Cite

In this work, we measured N self-diffusion in the Co-N system and found an unexpected result that N diffuses out almost completely around 500 K, leaving behind fcc Co irrespective of the amount of N used to deposit Co-N. On the other hand, in previous attempts the Co 4 N phase has always been grown at 550 K or above. In view of our finding, it appears that fcc Co could have been mistaken for Co 4 N, probably due to the closeness of their lattice parameters (LP; fcc Co = 3.54 Å, Co 4 N= 3.74 Å). Therefore, Co 4 N -an interesting material for its high spin-polarization ratio and high magnetic moment remained unexplored. By bringing down the growth temperature, we report the growth of stoichiometric Co 4 N epitaxial thin films. Films were grown using a direct current reactive magnetron sputtering process on LaAlO 3 (LAO mismatch 1.4%) and MgO (mismatch 11.3%) substrates and their structural and magnetic properties were studied. Precise magnetic moment (M s ) of Co 4 N samples were measured using polarized neutron reflectivity and compared with bulk magnetization results. We found that the M s of Co 4 N is higher due to a magnetovolume effect. Unlike previous findings, we observed that substrates induce misfit strain and strain inhomogeneity is the cause of modifications in magnetic ensemble such as coercivity, saturation magnetization, and magnetic anisotropy. A consequence of incoherent strain present in our samples is also reflected in the magnetic anisotropy leading to a superposition of strong fourfold and a small fraction of uniaxial magnetic anisotropy. Obtained results are presented and discussed in this work.