Critical fields of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Fe</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>N/NbN ferromagnetic/superconducting multilayers

Mattson, J. E.; Potter, C. D.; Conover, M. J.; Sowers, C. H.; Bader, S. D.

doi:10.1103/physrevb.55.70

Cited by 35 publications

(19 citation statements)

References 20 publications

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“…According to Fig. 3, the temperature dependence of DC susceptibility of the nanoparticles at a field of 100 Oe confirms that the critical temperature (T C ) of the NbN nanoparticles occurs at 15.1 K. Referring to the previous reference [22], the coherence length of bulk NbN is $ 10 nm, which is important for maintaining a superconducting state. The T C (15.1 K) of the as-prepared NbN nanoparticles is slightly less than that of 17 K for a bulk NbN.…”

Section: Resultssupporting

confidence: 63%

“…The superconducting transition temperature T c of the nanoparticles as a function of their size d has been studied both theoretically and experimentally. The reduction of the particle's size d could lead to dramatic changes of the physical behavior of superconductors, such as a reduction on the critical temperature and/or superconducting state of nanosized superconductors [7,20,22]. The possible origin for the slight reduction of superconducting transition temperature is that this is an effect of increased surface area, which may enhance surface electron-phonon scattering effect and compensate the size effect of reducing superconducting transition temperature [18,19].…”

Section: Resultsmentioning

confidence: 96%

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Facile synthesis of superconducting NbN nanoparticles

Liu

Zhou

et al. 2015

Ceramics International

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 96%

Facile synthesis of superconducting NbN nanoparticles

Liu

Zhou

et al. 2015

Ceramics International

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“…During the past decade, most experimental work on γ′-Fe 4 N was devoted to produce it as an epitaxial thin film [13,37,42,[53][54][55][56][57][58][59][60][61][62][63][64] or as a part of multilayer systems [65,66], using different substrates and growth methods. Table 2 lists a set of synthesis methods and conditions we could find in the literature for samples for which the magnetization has been measured.…”

Section: History and Interestmentioning

confidence: 99%

The magnetization of γ′‐Fe₄N: theory vs. experiment

Blancá

Desimoni

Christensen

et al. 2009

Physica Status Solidi (b)

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By reviewing the experimental and theoretical literature on γ′‐Fe4N, and by a systematic survey of predictions by the LDA, PBE, WC, LDA + U (2×), PBE + U (2×) and B3PW91 exchange‐correlation functionals, the structural, magnetic and hyperfine properties of this material as well as their pressure dependencies are interpreted. The hypothesis is put forward that γ′‐Fe4N as found in Nature is exactly at a steep transition between low‐spin and high‐spin behaviour. PBE + U (U = 0.4 eV) is identified as the most accurate exchange‐correlation functional for this material, although it is needed to fix the magnetization at the experimental value to obtain a satisfying description. Remaining disagreement between theory and experiment is pointed out. A recent experimental claim for a giant magnetic moment in γ′‐Fe4N is discussed, and is not reproduced by our calculations. We expect that the new insight obtained in the present work can lead to a consistent ab initio modeling of other materials in the iron‐nitrogen binary system. In an accompanying didactic section, the physics behind some common exchange‐correlation functionals is outlined. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Most of the papers devoted to upper critical magnetic fields measurements in S/F hybrids reported, in fact, on the study of coupling phenomena between the superconducting layers and on the analysis of the dimensional crossover in the temperature dependence of the parallel critical field. [17][18][19][20][21][22][23][24] In this paper we investigate the superconducting properties of Nb/ Cu 0.41 Ni 0.59 / Nb and Nb/ Pd 0.81 Ni 0.19 / Nb trilayers by measuring the critical temperatures and the temperature dependence of the perpendicular and parallel critical fields H c2Ќ ͑T͒ and H c2ʈ ͑T͒, respectively, as a function of d F . In particular we focused on the influence of the -phase state on the anisotropy which is an intrinsic property of such layered structures.…”

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confidence: 99%

Nonmonotonic behavior of the anisotropy coefficient in superconductor-ferromagnet-superconductor trilayers

et al. 2009

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We have measured critical temperatures and upper critical magnetic fields as a function of the ferromagnetic layer thickness, d F , in two different superconductor͑S͒/ferromagnet͑F͒/superconductor͑S͒ triple layers: Nb/ Cu 0.41 Ni 0.59 / Nb and Nb/ Pd 0.81 Ni 0.19 / Nb. We vary d F from the 0-phase coupling to the -phase coupling regime and find strong nonmonotonic behavior of the anisotropy coefficient ␥ GL = H c2ʈ ͑0͒ / H c2Ќ ͑0͒ characterized by an initial increase, a peak, and a subsequent decrease. The peak is a manifestation of the small coupling which exists around the 0-transition and it is qualitatively in agreement with recent theoretical predictions ͓B. Krunavakarn and S. Yoksan, Physica C 440, 25 ͑2006͔͒ which includes the effect of the different interface transparencies of the two systems. The experimental results demonstrate that the occurrence of the phase strongly influences the transport properties of S/F/S systems in external fields. The proximity effect in superconductor ͑S͒/ferromagnet ͑F͒ hybrids has recently attracted a lot of interest due to the inhomogeneous nature of the superconducting order parameter in these structures.1-3 One of the most relevant consequences of the peculiar character of the order parameter is the nonmonotonic behavior of the superconducting critical temperature T c as a function of the thickness d F of the F layer which has been observed in many S/F heterostructures.4-6 Also, in the so-called S/F/S Josephson junctions negative critical currents have been measured. [7][8][9] What essentially happens is that the interaction of the Cooper pairs with the exchange field E ex causes the order parameter to oscillate on the F side of the interface over a distance F , the coherence length in the ferromagnet. On the other hand, on the S side, the order parameter is strongly suppressed over a distance of the order of the superconducting coherence length S , which, in conventional superconductors such as Nb, is usually of a few nanometers. In weak ferromagnetic alloys such as PdNi and CuNi, due to the smaller value of E ex , F is of the order of some nanometers. In the dirty limitwhere D F is the diffusion coefficient of the F metal. Another characteristic length introduced when studying S/F hybrids is F ‫ء‬ = ͱ បD F / 2k B T c which is a measure of the diffusive motion of the Cooper pairs in the ferromagnet and which will be needed in order to compare our data with theoretical calculations. However, the strength of the proximity effect between the S and F layers depends also on the quality of the interfaces. An important parameter in the theoretical description therefore is the interface transparency, T.10,11 Its influence on the behavior of the T c both as a function of the thickness d S of the S layer and of d F has been studied both in Nb/CuNi and Nb/PdNi bilayers 12,13 and also, more recently, the behavior of the parallel upper critical field in these systems has been considered.14 All these studies revealed a somehow higher value of the interface transparency in the Nb/PdN...

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Critical fields ofFe4N/NbN ferromagnetic/superconducting multilayers

Cited by 35 publications

References 20 publications

Facile synthesis of superconducting NbN nanoparticles

Facile synthesis of superconducting NbN nanoparticles

The magnetization of γ′‐Fe₄N: theory vs. experiment

Nonmonotonic behavior of the anisotropy coefficient in superconductor-ferromagnet-superconductor trilayers

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Critical fields ofFe4N/NbN ferromagnetic/superconducting multilayers

Cited by 35 publications

References 20 publications

Facile synthesis of superconducting NbN nanoparticles

Facile synthesis of superconducting NbN nanoparticles

The magnetization of γ′‐Fe4N: theory vs. experiment

Nonmonotonic behavior of the anisotropy coefficient in superconductor-ferromagnet-superconductor trilayers

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The magnetization of γ′‐Fe₄N: theory vs. experiment