Properties of Fe(Se, Te) Bicrystal Grain Boundary Junctions, SQUIDs, and Nanostrips

Sarnelli, E.; Nappi, C.; Camerlingo, C.; Enrico, Emanuele; Kawale, S.; Braccini, V.; Leveratto, Alessandro

doi:10.1109/tasc.2016.2636248

Cited by 20 publications

(23 citation statements)

References 16 publications

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“…Compared to the cuprates, those values are two orders of magnitude lower.As a result, the I c R N product was 18∼33 µV, where I c is the Josephson critical current. Later, Sarnelli et al fabricated dc superconducting quantum interference devices (dc-SQUIDs) using 100-nm thick Fe(Se,Te) bicrystal with θ GB = 24 • 65,…”

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confidence: 99%

“…The θ GB dependence of inter-grain J c for various FBS bicrystals. The data were acquired at 4 K for P:Ba-122 34 and Co:Ba-12270,71 , whereas for Fe(Se,Te)65,67 and NdFeAs(O,F) 61 the measurements were conducted at 4.2 K. For comparison, the data of YBa 2 Cu 3 O 7 (YBCO) measured at 4 K were also plotted 81. (b) The ratio of J GB c /J Grain c as a function of θ GB for various FBS.…”

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confidence: 99%

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Fe-based superconducting thin films on metallic substrates: Growth, characteristics, and relevant properties

Iida

Hänisch

Tarantini

2018

Applied Physics Reviews

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The discovery of Fe-based superconductors (FBS) as the second class of high-temperature superconducting transition (high-T c ) materials after the cuprates generated a significant impact on the community of fundamental and applied superconductivity research. Whenever a new class of high-T c superconducting materials is discovered, a lot of effort is devoted to growing single crystals and epitaxial thin films for exploring basic physical quantities. Although several properties of FBS are similar to the cuprates (large upper critical fields, as a consequence short coherence lengths, and small carrier density), others are distinctly different. For instance, in FBS the symmetry of the superconducting order parameter is most likely not a d-wave but an s±-wave, depending on the stoichiometry, crystallographic system, and doping level. Additionally, the critical current densities of FBS are less sensitive to the presence of grain boundaries (GBs) than those of the high-T c cuprates. These features are highly beneficial for the realization of cheaper conductors for high-field magnets at low temperatures. Indeed, several groups have demonstrated FBS thin films on technical metallic substrates and powder-in-tube processed FBS wires as proof-of-principle studies for conductor applications. FBS on technical substrates also give many opportunities for studying how GB networks affect the critical current and how uniaxial strain impacts the superconducting properties. In this article, we review FBS thin films, especially on technical metallic substrates, and focus on application-relevant properties like pinning improvement by natural and artificial defects as well as the transparency of grain boundaries and GB networks. The recent development of FBS thin films on technical substrates and their superconducting properties are presented and the performance gap with respect to films on single crystals is discussed.

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confidence: 99%

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confidence: 99%

Fe-based superconducting thin films on metallic substrates: Growth, characteristics, and relevant properties

Iida

Hänisch

Tarantini

2018

Applied Physics Reviews

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“…The ball-milling energy, E BM , which is a function of the milling duration and the number of rotations [24], was systematically varied as 50, 80, 230, and 590 MJ/kg. Compacted, alloyed powder samples were sintered at 600 °C for 48 h under vacuum [34].…”

Section: Methodsmentioning

confidence: 99%

“…Iron-based superconductors also have inherently weak links [20][21][22]. Previous studies have shown that the transport critical current in Fe (Se,Te) decreases to approximately 1/5th-1/4th at a misorientation angle of 15° compared to that at 0° and further decreases by an order of magnitude at 25° [21][22][23][24][25]. In our previous study, we found a correlation between the improvement in critical current characteristics and the reduction in grain size by microstructural analysis using electron microscopy [26].…”

Section: Introductionmentioning

confidence: 99%

3D microstructure and critical current properties of ultra-fine-grain Ba(Fe,Co)2As2 bulk superconductors

Shimada

Tokuta

Yamanaka

et al. 2021

Preprint

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In iron-based superconductors, randomly oriented grain boundaries have a strong influence on the transport properties via intrinsic weak-link and flux pinning mechanisms. Herein we report the critical current density (Jc) and the three-dimensional microstructure of polycrystalline bulk Co-doped Ba122 superconductors, with highly dense grain boundaries (grain size smaller than 50 nm), produced by high-energy milling. Three-dimensional electron microscopy revealed that the anomalous growth of secondary particles (aggregation) and the inter-aggregation structures were significantly different in the samples with finer grains, which may have extrinsically limited Jc. These important microstructural features were quantified as two parameters—local thickness and total pore length—by reconstructing the three-dimensional structure of the superconducting phase using the adaptive thresholding method. The results obtained in this study suggest that understanding and controlling the microstructural formation process by sintering are instrumental for improving the Jc properties of 122 polycrystalline materials consisting of ultrafine grains.

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“…Hence, the critical current density (J c ) of FBS across the GB is expected to be not as severely reduced as cuprates. In fact, the critical angle (θ c ), above which J c starts to decrease exponentially, is around 9 • for Co-doped BaFe 2 As 2 (Ba-122) [11] and Fe(Se,Te) [12,13], much larger than YBa 2 Cu 3 O 7 (θ c =3 • ∼5 • ) [14]. Additionally, the grain boundaries for Co-and P-doped Ba-122 [11,15], and Fe(Se,Te) [12,13] are of metallic nature.…”

Section: Introductionmentioning

confidence: 99%

Grain boundary characteristics of oxypnictide NdFeAs(O,F) superconductors

Iida

Omura

Matsumoto

et al. 2019

Supercond. Sci. Technol.

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We have systematically investigated the grain boundary angle (θ GB ) dependence of transport properties for NdFeAs(O,F) fabricated on [001]-tilt symmetric MgO bicrystal substrates. In our previous study, NdFeAs(O,F) bicrystal films showed a weak-link behaviour even at a θ GB of 6 • . However, this was caused by an extrinsic effect originating from the damage to both NdFeAs(O,F) and MgO substrate by excess F-diffusion along the grain boundary. To investigate the intrinsic nature of grain boundaries, we minimized the damage to NdFeAs(O,F) and MgO by reducing the deposition temperature of NdOF over-layer needed for F-doping. The resultant NdFeAs(O,F) bicrystal films have a critical angle of 8.5 • , above which J c starts to decrease exponentially. This critical angle is almost the same as those of other Febased superconductors. arXiv:1904.03561v1 [cond-mat.supr-con] 7 Apr 2019Grain boundary characteristics of oxypnictide NdFeAs(O,F) superconductors c for θ GB =12 • was defined as the intersection between E = 0 and a linear fit to the non-ohmic linear differential (NOLD) region (i.e. the region where E increased linearly with the current density J).

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Properties of Fe(Se, Te) Bicrystal Grain Boundary Junctions, SQUIDs, and Nanostrips

Cited by 20 publications

References 16 publications

Fe-based superconducting thin films on metallic substrates: Growth, characteristics, and relevant properties

Fe-based superconducting thin films on metallic substrates: Growth, characteristics, and relevant properties

3D microstructure and critical current properties of ultra-fine-grain Ba(Fe,Co)2As2 bulk superconductors

Grain boundary characteristics of oxypnictide NdFeAs(O,F) superconductors

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