Huge critical current density and tailored superconducting anisotropy in SmFeAsO0.8F0.15 by low-density columnar-defect incorporation

Fang, Lei; Jia, Ying; Mishra, Vivek; Chaparro, Carlos; Vlasko-Vlasov, V. K.; Koshelev, A. E.; Welp, U.; Crabtree, G. W.; Zhu, S.; Zhigadlo, N. D.; Katrych, S.; Karpiński, J.; Kwok, W. K.

doi:10.1038/ncomms3655

Cited by 75 publications

(64 citation statements)

References 38 publications

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“…Here most of the experiments were carried out on single crystal samples, and Jc was determined by magnetic hysteresis loop (MHL) measurements. To summarize the results, (1) Jc of Fe-based superconductors is generally high: Jc ~ 2 MA/cm 2 at 5 K and 0 T for SmFeAsO1-xFx [11], ~ 2 MA/cm 2 for KBa122 [24], ~ 0.1 MA/cm 2 for LiFeAs [25], and ~ 0.2 MA/cm 2 for FeTe1-xSex [26], respectively. (2) The MHL measurements show a sharp peak at around zero field and a power-law decay of Jc at low-field region, which are attributed to the strong pinning [27,28].…”

Section: Introductionmentioning

confidence: 99%

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Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

et al. 2017

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* Both authors contributed equally to this work.In order to establish the doping dependence of the critical current properties in the iron-based superconductors, the in-plane critical current density (Jc) of BaFe2As2-based superconductors, Ba1-xKxFe2As2 (K-Ba122), Ba(Fe1-xCox)2As2 (Co-Ba122), and BaFe2(As1-xPx)2 (P-Ba122) in a wide range of doping concentration (x) was investigated by means of magnetization hysteresis loop (MHL) measurements on single crystal samples. Depending on the dopant elements and their concentration, Jc exhibits a variety of magneticfield (H)-and temperature (T)-dependences. (1) In the case of K-Ba122, the MHL of the under-doped samples (x ≤ 0.33) exhibits the second magnetization peak (SMP), which sustains high Jc at high H and high T, exceeding 10 5 A/cm 2 at T = 25 K and µ0H = 6 T for x = 0.30. On the other hand, the SMP is missing in the optimally-(x ~ 0.36-0.40) and over-doped (x ~ 0.50) samples, and consequently Jc rapidly decreases by more than one order of magnitude, although the change in Tc is within a few K. (2) For Co-Ba122, the SMP is always present over the entire superconducting (SC) dome from the under-(x ~ 0.05) to the over-doped (x ~ 0.12) region. However, the magnitude of Jc significantly changes with x, exhibiting a sharp maximum at x ~ 0.057, which is a slightly under-doped composition among Co-Ba122. (3) For P-Ba122, the highest Jc is attained at x = 0.30 corresponding to the highest Tc composition. For the over-doped samples, the MHL is characterized by a SMP located close to the irreversibility field Hirr. Common to the three doping variations, Jc becomes highest at the under-doping side of the SC dome near the phase boundary between the SC phase and the antiferromagnetic/orthorhombic (AFO) phase. Also, the peak appears in a narrow range of doping, distinct from the Tc dome with broad maximum. These similarities in the three cases indicate that the observed doping dependence of Jc is intrinsic to the BaFe2As2-based superconductors. The scaling analysis of the normalized pinning force density fp as a function of the reduced magnetic field h = H/Hirr (Hirr: irreversibility field) shows that the peak in the pinning force position (hmax) depends on x, indicating a change in pinning with x. On the other hand, high-Jc samples always attain similar hmax values of 0.40-0.45 for all the dopants, which may suggest that a common pinning source causes the highest Jc. A quantitative analysis of the Tdependent Jc indicates that the two pinning mechanisms, namely, the spatial variations in Tc (referred to as Tc pinning) and the fluctuations in the mean free path (l pinning), are enhanced for the under-doped samples, which results in the enhancement of Jc. Possible origins for the different pinning mechanism are discussed in connection with the x-dependence of Tc, the residual resistivity, AFO domain boundaries, and a possible quantum critical point.

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Section: Introductionmentioning

confidence: 99%

“…It was also demonstrated that the introduction of artificial pinning centers by irradiation with heavy-irons, neutrons, electrons, etc. largely enhances Jc [9][10][11][12]. At this moment, the improvement of inter-grain connectivity is one of the challenges for applications such as powder-in-tube wires and tapes [13,14].…”

Section: Introductionmentioning

confidence: 99%

Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

et al. 2017

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“…Among the various iron based superconductors, 122-type (AE)Fe 2 As 2 (AE = Sr, Ba) is very attractive for high field applications due to its excellent properties such as very high upper critical field (H c2 ), relatively small anisotropy [10,11], and an advantageous grain-boundary nature [12]. In order to achieve high critical current density (J c ) various processing techniques have been used [13][14][15][16][17][18]. Among these proposed processes, the powder-in-tube (PIT) method seems the most promising technique for practical applications [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

High transportJ_cin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

Gao

Togano

Matsumoto

et al. 2014

Supercond. Sci. Technol.

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Abstract:The recently discovered iron-based superconductors with very high upper critical field (H c2 ) and small anisotropy have been regarded as a potential candidate material for high field applications. However, enhancements of superconducting properties are still needed to boost the successful use of iron-based superconductors in such applications. Here, we propose a new sheath architecture of stainless steel (SS)/Ag double sheath and investigate its influence on the microstructures and J c -H property.We found that the transport J c -H curves for rolled and pressed tapes both show extremely small magnetic field dependence and exceed 3×10 4 A/cm 2 under 28 T, which are much higher than those of low-temperature superconductors. More interestingly, 12 cm long rolled tape shows very high homogeneity and sustains J c as high as 7.7×10 4 A/cm 2 at 10 T. These are the highest values reported so far for iron-based superconducting wires fabricated by scalable rolling process. The microstructure investigations indicate that such high J c was achieved by higher density of the core and uniform deformation resulting better texturing. These results indicate that our process is very promising for fabricating long Ba122 wires for high field magnet, i.e. above 20 T.* Author to whom correspondence should be addressed; E-mail: KUMAKURA.Hiroaki@nims.go.jp 2The recently discovered iron-based superconductors have attracted great interest as a subject of both fundamental study and practical applications [1][2][3][4][5][6][7][8][9]. Among the various iron based superconductors, 122-type (AE)Fe 2 As 2 (AE = Sr, Ba) is very attractive for high field applications due to its excellent properties such as very high upper critical field (H c2 ), relatively small anisotropy [10,11], and an advantageous grain-boundary nature [12]. In order to achieve high critical current density (J c ) various processing techniques have been used [13][14][15][16][17][18]. Among these proposed processes, the powder-in-tube (PIT) method seems the most promising technique for practical applications [19][20][21]. Thus, the Ba(Sr)122 PIT wires have been investigated intensively [22][23][24][25][26][27][28][29][30][31], and high J c exceeding the level of 10 4 A/cm 2 at 4.2 K and 10 T has been reported for short samples prepared by applying uniaxial pressing [32][33][34][35].However, unfortunately, pressing processes are usually applicable only for a short sample and it is difficult to attain such high J c values with good reproducibility. For practical applications, it is desirable if high J c values are attained with good reproducibility by rolling, which is easy to scale up to the long length wire production.Although silver looks the most suitable sheath material for 122 phase, there are a number of drawbacks of using pure Ag as the sheathing material: poor mechanical properties after the heat treatment that make the coil winding difficult and limit its ability to support Lorentz forces in high magnetic fields, and high occurrence of sausaging during mechan...

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“…The stronger intra-grain pinning observed in the 1111 HTSC-Fe family compared to the 11-HTSC Fe and its technological control via correlated nanoscale defects [64] will have application relevance. However keep in mind that in the fabrication of the superconducting wires and tapes the limiting factor of the critical current are mainly the grain boundaries, then as a first step need solve this technologically relevant fact [65].…”

Section: Resultsmentioning

confidence: 99%

Effect of spacer layer on flux-pinning properties of iron-based superconductors

Gioacchino¹,

Poccia²,

Marcelli³

et al. 2016

Novel Superconducting Materials

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Abstract:We investigated the magnetic flux-pinning in iron-based 1111-type (REFeAsO, RE= rare earth) and 11-type (FeSe 1−x Tex) superconductors by third harmonic acmagnetic susceptibility measurements, a technique sensitive to the dynamics of magnetization, probing non-linear processes in flux pinning transport. Despite the larger thermal fluctuations due to the high critical temperature and large anisotropy, flux dynamics of 1111-type pnictides points out a more efficient pinning mechanism than the one in the 11-type chalcogenides. We have associated the stronger pinning in the 1111-family to the presence of REO (RE=rare earth) spacer layers separating the active FeAslayers unlike the 11-chalcogenides in which no spacer layers are present. Therefore, the disorder in the FeAs layers induced by the misfit strain due to spacer layers has an important role in the enhanced flux pinning of 1111-type superconductors.

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Huge critical current density and tailored superconducting anisotropy in SmFeAsO0.8F0.15 by low-density columnar-defect incorporation

Cited by 75 publications

References 38 publications

Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

High transportJ_cin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

Effect of spacer layer on flux-pinning properties of iron-based superconductors

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Huge critical current density and tailored superconducting anisotropy in SmFeAsO0.8F0.15 by low-density columnar-defect incorporation

Cited by 75 publications

References 38 publications

Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

High transportJcin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

Effect of spacer layer on flux-pinning properties of iron-based superconductors

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High transportJ_cin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process