Interface sharpening in miscible and isotopic multilayers: Role of short-circuit diffusion

Tiwari, Atul; Tiwari, M. K.; Gupta, Mukul; Wille, Hans‐Christian; Gupta, Ajay

doi:10.1103/physrevb.99.205413

Cited by 13 publications

(8 citation statements)

References 44 publications

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“…As we increase the T s , ∆ Fe increases albeit a small drop in pure Fe deposited at T s = 523 K. Such a drop in ∆ Fe can be due to an interface sharpening effect which happens due to release of defects and voids. Such interface sharpening was also evidenced recently in Fe thin films grown at 573 K [62] and also observed in earlier works [63][64][65][66]. At T s = 523 K, ∆ Fe in Fe 0.8 C 0.2 sample is still significantly smaller as compared to Fe but when samples were grown at T s = 773 K, a sudden rise in ∆ Fe can be seen in Fe 0.8 C 0.2 sample.…”

Section: Depth Profiling and Fe Self-diffusion Measurementssupporting

confidence: 85%

“…In an experimental study on Fe self-diffusion in Fe/ 57 Fe multilayers, it was also found E was small (E<<1 eV) and has been explained in terms of structural defects in Fe that lead to fast Fe diffusion during initial stages which subsequently becomes smaller when defects relaxation process gets completed [74]. In a recent study also, fast Fe diffusion has been observed and explains in terms of triple junctions leading to short-circuit diffusion [62]. In a way, the fast Fe diffusion during initial stages can be understood as grain boundary (gb) diffusion.…”

Section: E Phase Transformation Mechanismmentioning

confidence: 92%

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Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Kumar,

Reddy,

Ganesan

et al. 2019

Preprint

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We studied the structural and magnetic properties of Fe0.8C0.2 thin films deposited by cosputtering of Fe and C targets in a direct current magnetron sputtering (dcMS) process at a substrate temperature (Ts) of 300, 523 and 773 K. The structure and morphology was measured using x-ray diffraction (XRD), x-ray absorption near edge spectroscopy (XANES) at Fe L and C K-edges and atomic/magnetic force microscopy (AFM, MFM), respectively. An ultrathin (3 nm) 57 Fe0.8C0.2 layer, placed between relatively thick Fe0.8C0.2 layers was used to estimate Fe selfdiffusion taking place during growth at different Ts using depth profiling measurements. Such 57 Fe0.8C0.2 layer was also used for 57 Fe conversion electron Mössbauer spectroscopy (CEMS) and nuclear resonance scattering (NRS) measurements, yielding the magnetic structure of this ultrathin layer. We found from XRD measurements that the structure formed at low Ts (300 K) is analogous to Fe-based amorphous alloy and at high Ts (773 K), pre-dominantly a Fe3C phase has been formed. Interestingly, at an intermediate Ts (523 K), a clear presence of Fe4C (along with Fe3C and Fe) can be seen from the NRS spectra. The microstructure obtained from AFM images was found to be in agreement with XRD results. MFM images also agrees well with NRS results as the presence of multi-magnetic components can be clearly seen in the sample grown at Ts = 523 K. The information about the hybridization between Fe and C, obtained from Fe L and C K-edges XANES also supports the results obtained from other measurements. In essence, from this work, experimental realization of Fe4C has been demonstrated. It can be anticipated that by further fine-tuning the deposition conditions, even single phase Fe4C phase can be realized which hitherto remains an experimental challenge.

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Section: Depth Profiling and Fe Self-diffusion Measurementssupporting

confidence: 85%

Section: E Phase Transformation Mechanismmentioning

confidence: 92%

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Kumar,

Reddy,

Ganesan

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…As we increase the T s , Fe increases albeit a small drop in pure Fe deposited at T s = 523 K. Such a drop-in Fe can be due to an interface sharpening effect that happens due to the release of defects and voids. Such interface sharpening was also evidenced recently in Fe thin films grown at 573 K [63] 013402-7 FIG. 9.…”

Section: Depth Profiling and Fe Self-diffusion Measurementssupporting

confidence: 76%

“…In an experimental study on Fe self-diffusion in Fe/ 57 Fe multilayers, it was also found E was small (E 1 eV) and has been explained in terms of structural defects in Fe that lead to fast Fe diffusion during initial stages which subsequently becomes smaller when defects relaxation process gets completed [75]. In a recent study also, fast Fe diffusion has been observed and explains in terms of triple junctions leading to short-circuit diffusion [63]. In a way, the fast Fe diffusion during initial stages can be understood as grain boundary (gb) diffusion.…”

Section: E Phase Transformation Mechanismmentioning

confidence: 92%

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Kumar

Reddy

Ganesan

et al. 2020

Phys. Rev. Materials

Self Cite

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We studied the structural and magnetic properties of Fe 0.8 C 0.2 thin films deposited by co-sputtering of Fe and C targets in a direct current magnetron sputtering (dcMS) process at a substrate temperature (T s ) of 300, 523, and 773 K. The structure and morphology were measured using x-ray diffraction (XRD), x-ray absorption nearedge spectroscopy (XANES) at Fe L and C K edges and atomic/magnetic force microscopy (AFM, MFM). An ultrathin (3-nm) 57 Fe 0.8C0.2 layer, placed between relatively thick Fe 0.8 C 0.2 layers was used to estimate Fe selfdiffusion taking place during growth at different T s using depth profiling measurements. Such 57 Fe 0.8C0.2 layer was also used for 57 Fe conversion electron Mössbauer spectroscopy (CEMS) and nuclear resonance scattering (NRS) measurements, yielding the magnetic structure of this ultrathin layer. We found from XRD measurements that the structure formed at low T s (300 K) is analogous to Fe-based amorphous alloy and at high T s (773 K), predominantly a Fe 3 C phase has been formed. Interestingly, at an intermediate T s (523 K), a clear presence of Fe 4 C (along with Fe 3 C and Fe) can be seen from the NRS spectra. The microstructure obtained from AFM images was found to be in agreement with XRD results. MFM results also agree well with NRS as the presence of multi-magnetic components can be clearly seen in the sample grown at T s = 523 K. The information about the hybridization between Fe and C, obtained from Fe L-and C K-edge XANES also supports the results obtained from other measurements. In essence, from this work, a possibility for experimental realization of Fe 4 C has been demonstrated. It can be anticipated that by further fine-tuning of the deposition conditions, even single-phase Fe 4 C can be realized which hitherto remains an experimental challenge.

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“…Moreover, even the presence of negligible amount of O 2 in the deposition chamber can also form oxide layer in the substratefilm interface which was also evidenced in our samples. The O 2 base pressure was ≈ 7.5×10 −10 Torr in our chamber (measured using a residual gas analyzer) [43], and it seems that this negligible amount of O 2 readily reacts with Ti forming a thin (< 2 nm) Ti 2 O 3 phase during the early stage of growth (∆H 0 f = -1521 kJ mol −1 for Ti 2 O 3 compared to -337 kJ mol −1 for TiN). Detailed fitted parameters are listed in Table 3.…”

Section: X-ray Reflectivitymentioning

confidence: 74%

Synthesis and study of highly dense and smooth TiN thin films

Chowdhury¹,

Gupta²,

Prakash³

et al. 2020

Preprint

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This study aims towards a systematic reciprocity of the tunable synthesis parameters -partial pressure of N 2 gas, ion energy (E i ) and Ti interface in TiN thin film samples deposited using ion beam sputtering at ambient temperature (300 K). At the optimum partial pressure of N 2 gas, samples were prepared with or without Ti interface at E i = 1.0 or 0.5 keV. They were characterized using x-ray reflectivity (XRR) to deduce thickness, roughness and density. The roughness of TiN thin films was found to be below 1 nm, when deposited at the lower E i of 0.5 keV and when interfaced with a layer of Ti. Under these conditions, the density of TiN sample reaches to 5.80(±0.03) g cm −3 , a value highest hitherto for any TiN sample. X-ray diffraction and electrical resistivity measurements were performed. It was found that the cumulative effect of the reduction in E i from 1.0 to 0.5 keV and the addition of Ti interface favors (111) oriented growth leading to dense and smooth TiN films and a substantial reduction in the electrical resistivity. The reduction in E i has been attributed to the surface kinetics mechanism (simulated using SRIM) where the available energy of the sputtered species () leaving the target at E i = 0.5 keV is the optimum value favoring the growth of defects free homogeneously distributed films. The electronic structure of samples was probed using N K-edge absorption spectroscopy and the information about the crystal field and spin-orbit splitting confirmed TiN phase formation. In essence, through this work, we demonstrate the role of and Ti interface in achieving highly dense and smooth TiN thin films with low resistivity without the need of a high temperature or substrate biasing during the thin film deposition process.

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Interface sharpening in miscible and isotopic multilayers: Role of short-circuit diffusion

Cited by 13 publications

References 44 publications

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Synthesis and study of highly dense and smooth TiN thin films

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