The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Ajay Gupta - One of the best experts on this subject based on the ideXlab platform.
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study of magnetic Iron Nitride thin films deposited by high power impulse magnetron sputtering
Surface & Coatings Technology, 2015Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, V Ganesan, Layanta Behera, Surendra Singh, Saibal BasuAbstract:Abstract 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) techniques. The nitrogen partial pressure during deposition was systematically varied both in HiPIMS and dc-MS processes. Resulting Fe-N films were characterized for their microstructure, magnetic properties and nitrogen concentration. We found that HiPIMS deposited Fe-N thin films show improved soft magnetic properties and likely to possess globular nanocrystalline microstructure. In addition, it was found that the nitrogen reactivity with Fe get suppressed in HiPIMS discharge as compared to that in dc-MS plasma. Obtained results can be understood in terms of distinct plasma properties of HiPIMS discharge.
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study of magnetic Iron Nitride thin films deposited by high power impulse magnetron sputtering
arXiv: Materials Science, 2014Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, V Ganesan, Layanta Behera, Surendra Singh, Saibal BasuAbstract: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.
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Effect of dopants on thermal stability and self-diffusion in Iron-Nitride thin films
Physical Review B, 2014Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, N. P. Lalla, Michael Horisberger, Jochen Stahn, Kai Schlage, Hans-christian WilleAbstract:We studied the effect of dopants (Al, Ti, Zr) on the thermal stability of Iron Nitride thin films prepared using a dc magnetron sputtering technique. Structure and magnetic characterization of deposited samples reveal that the thermal stability together with soft magnetic properties of Iron Nitride thin films get significantly improved with doping. To understand the observed results, detailed Fe and N self-diffusion measurements were performed. It was observed that N self-diffusion gets suppressed with Al doping whereas Ti or Zr doping results in somewhat faster N diffusion. On the other hand Fe self-diffusion seems to get suppressed with any dopant of which heat of Nitride formation is significantly smaller than that of Iron Nitride. Importantly, it was observed that N self-diffusion plays only a trivial role, as compared to Fe self-diffusion, in affecting the thermal stability of Iron Nitride thin films. Based on the obtained results effect of dopants on self-diffusion process is discussed.
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Nanocrystalline Iron Nitride films with perpendicular magnetic anisotropy
Applied Physics Letters, 2008Co-Authors: Ajay Gupta, Ranu Dubey, Wolfram Leitenberger, Ulrich PietschAbstract:Nanocrystalline α-Iron Nitride films have been prepared using reactive ion-beam sputtering. Films develop significant perpendicualr magnetic anisotropy (PMA) with increasing thickness. A comparison of x-ray diffraction patterns taken with scattering vectors in the film plane and out of the film plane provides a clear evidence for development of compressive strain in the film plane with thickness. Thermal annealing results in relaxation of the strain, which correlates very well with the relaxation of PMA. This suggests that the observed PMA is a consequence of the breaking of the symmetry of the crystal structure due to the compressive strain.
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Amorphization in Iron Nitride thin films prepared by reactive ion-beam sputtering
Physical Review B, 2006Co-Authors: Ranu Dubey, Ajay Gupta, J.c. PivinAbstract:Reactive ion-beam sputtering has been used to prepare Iron Nitride over a wide composition range. It is found that the samples deposited at room temperature exhibit amorphous phase in the composition range from $12\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen to $23\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen. For samples deposited at liquid nitrogen temperature the system is amorphous up to $35\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen. Amorphization can be understood in terms of a frustration in the system due to a competition between $\ensuremath{\alpha}$ and $\ensuremath{\epsilon}$ phases. Kinetic constraints are also found to play a role in the amorphization process. M\"ossbauer measurements suggest that the local order in the amorphous phase consists of a mixture of $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$--like and $\ensuremath{\epsilon}\text{\ensuremath{-}}{\mathrm{Fe}}_{3}\mathrm{N}$--like short-range orders. On the Iron rich side the amorphous phase exhibits two-step crystallization, with a primary $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$ phase precipitating out in the first step. Around $22\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen the system exhibits a single step isomorphous transformation to $\ensuremath{\epsilon}$ phase. Thus, amorphous Iron Nitride phases exhibit behavior very similar to the conventional transition metal-metalloid amorphous alloys. In the remaining composition range nanocrystalline phases are formed. The amorphous magnetic Iron Nitride phases are expected to have distinct advantages over their crystalline counterparts in terms of soft magnetic applications.
J.c. Pivin - One of the best experts on this subject based on the ideXlab platform.
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Amorphization in Iron Nitride thin films prepared by reactive ion-beam sputtering
Physical Review B, 2006Co-Authors: Ranu Dubey, Ajay Gupta, J.c. PivinAbstract:Reactive ion-beam sputtering has been used to prepare Iron Nitride over a wide composition range. It is found that the samples deposited at room temperature exhibit amorphous phase in the composition range from $12\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen to $23\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen. For samples deposited at liquid nitrogen temperature the system is amorphous up to $35\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen. Amorphization can be understood in terms of a frustration in the system due to a competition between $\ensuremath{\alpha}$ and $\ensuremath{\epsilon}$ phases. Kinetic constraints are also found to play a role in the amorphization process. M\"ossbauer measurements suggest that the local order in the amorphous phase consists of a mixture of $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$--like and $\ensuremath{\epsilon}\text{\ensuremath{-}}{\mathrm{Fe}}_{3}\mathrm{N}$--like short-range orders. On the Iron rich side the amorphous phase exhibits two-step crystallization, with a primary $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$ phase precipitating out in the first step. Around $22\phantom{\rule{0.3em}{0ex}}\mathrm{at}.\phantom{\rule{0.2em}{0ex}}%$ nitrogen the system exhibits a single step isomorphous transformation to $\ensuremath{\epsilon}$ phase. Thus, amorphous Iron Nitride phases exhibit behavior very similar to the conventional transition metal-metalloid amorphous alloys. In the remaining composition range nanocrystalline phases are formed. The amorphous magnetic Iron Nitride phases are expected to have distinct advantages over their crystalline counterparts in terms of soft magnetic applications.
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Amorphization in Iron Nitride thin films prepared by reactive ion-beam sputtering
Physical Review B: Condensed Matter and Materials Physics, 2006Co-Authors: R. Dubey, Anupam Gupta, J.c. PivinAbstract:Reactive ion-beam sputtering has been used to prepare Iron Nitride over a wide composition range. It is found that the samples deposited at room temperature exhibit amorphous phase in the composition range from 12 at. % nitrogen to 23 at. % nitrogen. For samples deposited at liquid nitrogen temperature the system is amorphous up to 35 at. % nitrogen. Amorphization can be understood in terms of a frustration in the system due to a competition between alpha and epsilon phases. Kinetic constraints are also found to play a role in the amorphization process. Mössbauer measurements suggest that the local order in the amorphous phase consists of a mixture of alpha-Fe–like and epsilon-Fe3N–like short-range orders. On the Iron rich side the amorphous phase exhibits two-step crystallization, with a primary alpha-Fe phase precipitating out in the first step. Around 22 at. % nitrogen the system exhibits a single step isomorphous transformation to epsilon phase. Thus, amorphous Iron Nitride phases exhibit behavior very similar to the conventional transition metal-metalloid amorphous alloys. In the remaining composition range nanocrystalline phases are formed. The amorphous magnetic Iron Nitride phases are expected to have distinct advantages over their crystalline counterparts in terms of soft magnetic applications.
Olaf Schulte - One of the best experts on this subject based on the ideXlab platform.
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Characterization of magnetron-sputtered chromium and Iron Nitride films
Surface and Coatings Technology, 1997Co-Authors: T. Kacsich, Matthias Niederdrenk, Peter Schaaf, Klaus-peter Lieb, U. Geyer, Olaf SchulteAbstract:Abstract Chromium and Iron Nitride layers (with thicknesses of 100–1000 nm) were deposited onto silicon substrates via reactive rf magnetron sputtering. Stoichiometry, phase formation and surface morphology were analyzed by a combination of different methods: Rutherford Backscattering Spectrometry, Resonant Nuclear Reaction Analysis, Conversion Electron Mossbauer Spectroscopy, Scanning Tunneling Microscopy and X-Ray Diffraction.
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Characterization of magnetron-sputtered ε Iron-Nitride films
Journal of Alloys and Compounds, 1996Co-Authors: Matthias Niederdrenk, Peter Schaaf, Klaus-peter Lieb, Olaf SchulteAbstract:Iron Nitride films of 250–450 nm thickness were produced over a wide range of compositions by reactive magnetron sputtering. These films were analyzed by a combination of conversion electron Mossbauer spectroscopy (CEMS), Rutherford backscattering spectrometry (RBS), resonant nuclear reaction analysis (RNRA) and X-ray diffraction. The Iron and nitrogen concentration profiles and thus the compositions of the samples were determined by RBS and RNRA. With the known dependence of the lattice constant on the nitrogen content for the e-Fe2N1−z Nitride it was also possible to determine the composition via the analysis of the X-ray diffraction pattern. For e-Fe2N1−z (0 ⩽ z ⩽ 0.33) the CEMS spectra could be well resolved in terms of different Iron sites (envIronments), enabling an accurate determination of the nitrogen content in the 150 nm sampling range near the surface. It has been confirmed experimentally that the paramagnetic e-Fe2N1−z phase with z ⩽ 0.13 also has two different Iron sites. Thus it was possible to compare the compositions obtained by the four different methods. For the hexagonal e Iron-Nitride phase, Mossbauer spectroscopy proves that it experiences an ordering of the nitrogen atoms on the interstitial sites.
Akhil Tayal - One of the best experts on this subject based on the ideXlab platform.
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study of magnetic Iron Nitride thin films deposited by high power impulse magnetron sputtering
Surface & Coatings Technology, 2015Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, V Ganesan, Layanta Behera, Surendra Singh, Saibal BasuAbstract:Abstract 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) techniques. The nitrogen partial pressure during deposition was systematically varied both in HiPIMS and dc-MS processes. Resulting Fe-N films were characterized for their microstructure, magnetic properties and nitrogen concentration. We found that HiPIMS deposited Fe-N thin films show improved soft magnetic properties and likely to possess globular nanocrystalline microstructure. In addition, it was found that the nitrogen reactivity with Fe get suppressed in HiPIMS discharge as compared to that in dc-MS plasma. Obtained results can be understood in terms of distinct plasma properties of HiPIMS discharge.
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study of magnetic Iron Nitride thin films deposited by high power impulse magnetron sputtering
arXiv: Materials Science, 2014Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, V Ganesan, Layanta Behera, Surendra Singh, Saibal BasuAbstract: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.
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Effect of dopants on thermal stability and self-diffusion in Iron-Nitride thin films
Physical Review B, 2014Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, N. P. Lalla, Michael Horisberger, Jochen Stahn, Kai Schlage, Hans-christian WilleAbstract:We studied the effect of dopants (Al, Ti, Zr) on the thermal stability of Iron Nitride thin films prepared using a dc magnetron sputtering technique. Structure and magnetic characterization of deposited samples reveal that the thermal stability together with soft magnetic properties of Iron Nitride thin films get significantly improved with doping. To understand the observed results, detailed Fe and N self-diffusion measurements were performed. It was observed that N self-diffusion gets suppressed with Al doping whereas Ti or Zr doping results in somewhat faster N diffusion. On the other hand Fe self-diffusion seems to get suppressed with any dopant of which heat of Nitride formation is significantly smaller than that of Iron Nitride. Importantly, it was observed that N self-diffusion plays only a trivial role, as compared to Fe self-diffusion, in affecting the thermal stability of Iron Nitride thin films. Based on the obtained results effect of dopants on self-diffusion process is discussed.
Saibal Basu - One of the best experts on this subject based on the ideXlab platform.
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study of magnetic Iron Nitride thin films deposited by high power impulse magnetron sputtering
Surface & Coatings Technology, 2015Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, V Ganesan, Layanta Behera, Surendra Singh, Saibal BasuAbstract:Abstract 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) techniques. The nitrogen partial pressure during deposition was systematically varied both in HiPIMS and dc-MS processes. Resulting Fe-N films were characterized for their microstructure, magnetic properties and nitrogen concentration. We found that HiPIMS deposited Fe-N thin films show improved soft magnetic properties and likely to possess globular nanocrystalline microstructure. In addition, it was found that the nitrogen reactivity with Fe get suppressed in HiPIMS discharge as compared to that in dc-MS plasma. Obtained results can be understood in terms of distinct plasma properties of HiPIMS discharge.
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study of magnetic Iron Nitride thin films deposited by high power impulse magnetron sputtering
arXiv: Materials Science, 2014Co-Authors: Akhil Tayal, Ajay Gupta, Mukul Gupta, V Ganesan, Layanta Behera, Surendra Singh, Saibal BasuAbstract: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.
