High, magnetic field independent critical currents in (Ba,K)Fe2As2 crystals

Fang, Lei; Jia, Ying; Chaparro, Carlos; Sheet, Goutam; Claus, H.; Kirk, M. A.; Koshelev, A. E.; Welp, U.; Crabtree, G. W.; Kwok, W. K.; Zhu, S.; Hu, Hefei; Zuo, Jian‐Min; Wen, Hao; Shen, Bin

doi:10.1063/1.4731204

Cited by 86 publications

(117 citation statements)

References 36 publications

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“…4 Fe 2 As 2 has demonstrated a nearly fieldindependent critical current density of J c ¼ 5 MA cm À 2 at 5 K and HB7 T (ref. 10). These J c (T,H) values are comparable to state-of-the-art YBa 2 Cu 3 O 7-d (YBCO)-coated conductors under similar conditions.…”

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confidence: 64%

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

et al. 2013

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Iron-based superconductors could be useful for electricity distribution and superconducting magnet applications because of their relatively high critical current densities and upper critical fields. SmFeAsO 0.8 F 0.15 is of particular interest as it has the highest transition temperature among these materials. Here we show that by introducing a low density of correlated nano-scale defects into this material by heavy-ion irradiation, we can increase its critical current density to up to 2 Â 10 7 A cm À 2 at 5 K-the highest ever reported for an ironbased superconductor-without reducing its critical temperature of 50 K. We also observe a notable reduction in the thermodynamic superconducting anisotropy, from 8 to 4 upon irradiation. We develop a model based on anisotropic electron scattering that predicts that the superconducting anisotropy can be tailored via correlated defects in semimetallic, fully gapped type II superconductors.

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confidence: 64%

“…33). The comparatively small reduction of anisotropy in the FeAs-122 materials can be attributed to the initial low anisotropy and the discontinuous morphology of the damage tracks 10 . Similar phenomena could be expected in high-T c cuprates, MgB 2 and other anisotropic superconductors.…”

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confidence: 99%

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

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“…3. The value of J c is quite high, J c (35 K) = 10.8 MA/cm 2 , which is at least three orders of magnitude larger than the previously reported results [7,11]. Since our J c data were obtained in the vicinity of T c at T /T c > 0.87, the ultimate J c (0) should be considerably higher.…”

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confidence: 42%

“…The J GL dp corresponds to the critical pair-breaking current, which was theoretically estimated to be as high as 200 MA/cm 2 at 0 K for (Ba,K)Fe 2 As 2 [11]. This value is two orders of magnitude larger than previously reported J c 's.…”

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confidence: 44%

“…J dp (0)/J GL dp (0) ≈ 0.385 [21]. Thus, we get to the value J dp (0) ≈363.6 MA/cm 2 that is still a bit higher than the estimated one (≈ 200 MA/cm 2 [11]) but of the same order or magnitude. We note that in our model we used a s-wave model for both gaps, and by using a different symmetry of the order parameter the value of the J dp can change at low temperatures.…”

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confidence: 76%

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Direct observation of the depairing current density in single-crystalline Ba0.5K0.5Fe2As2 microbridge with nanoscale thickness

Yuan

et al. 2013

Applied Physics Letters

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We investigated the critical current density (Jc) of Ba0.5K0.5Fe2As2 single-crystalline microbridges with thicknesses ranging from 276 to 18 nm. The J c of the microbridge with thickness down to 91 nm is 10.8 MA/cm 2 at 35 K, and reaches 944.4 MA/cm 2 by extrapolating Jc(T ) to T = 0 K using a two-gap s-wave Ginzburg-Landau model, well in accordance with the depairing current limit. The temperature, magnetic field, and angular-dependence of Jc(T, H, θ) indicated weaker field dependence and weakly anisotropic factor of 1.15 (1 T) and 1.26 (5 T), which also yielded the validity of the anisotropic Ginzburg-Landau scaling.The newly discovered Fe-based superconductors caused increasing attention due to their potential for applications, owing to high superconducting (SC) transition temperature (T c ), high upper critical fields (H c2 ), and a low critical current (J c ) anisotropy [1]. Compared with the layered cuprate family, although Fe-based superconductors have lower T c , they demonstrate nearly isotropic transport behavior [1]. Investigation of anisotropic J c is essential, from the view point of basic physics parameters and potential applications [2][3][4]. Generally, there are two main methods to explore the J c . The first one is to study patterned thin film micro-devices. The thin films have been fabricated successfully for several systems, including Fe(Se,Te) [2], Ba(Fe,Co) 2 As 2 [3], and LaFeAsO 1−x F x [4]. However, one can hardly obtain an ideal single-crystalline film, due to the presence of twins and low-angle grain boundaries resulting from the island-like growth process [5]. Although the existence of grain boundaries can enhance the J c by increasing pinning, the critical current exhibits exponential decay in the weak-link regime which poses a serious obstacle for practical applications. Up to now, the J c of Fe-based thin films was reported at the level of a few MA/cm 2 at 4.3 K [3][4][5]. The other method is to measure the J c indirectly from magnetization hysteresis loop (MHL) of single crystals. By using the Bean's model the J c can be evaluated from the vortex penetration profile [6], which is determined by pining force owing to the defects, grain boundary, and geometry of the materials. The J c value estimated from MHL remains as well of the order of a few MA/cm 2 at 4.3 K [7]. * Author to whom correspondence should be addressed. Electronic mail: Jun.Li@fys.kuleuven.beWe emphasize that both methods for J c determination are limited by the vortex motion in presence of a finite pining force, but not the intrinsic transport capability of the material, for which an exploration of the GinzburgLandau (GL) depairing current density (J GL dp ) is of great importance for understanding the existing limits for increasing J c [8][9][10]. The J GL dp corresponds to the critical pair-breaking current, which was theoretically estimated to be as high as 200 MA/cm 2 at 0 K for (Ba,K)Fe 2 As 2 [11]. This value is two orders of magnitude larger than previously reported J c 's. Generally, it is rather difficult t...

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