Neutron irradiation of MgB211: From the enhancement to the suppression of superconducting properties

Putti, M.; Braccini, V.; Ferdeghini, C.; Gatti, F.; Grasso, G.; Manfrinetti, P.; Marré, D.; Palenzona, A.; Pallecchi, I.; Tarantini, C.; Sheikin, I.; Aebersold, H. U.; Lehmann, Eberhard

doi:10.1063/1.1880450

Cited by 75 publications

(103 citation statements)

References 16 publications

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“…It is well documented that B c2 can be enhanced significantly by various techniques [1,2,3,4,5,6,7,8,9,10,11]. Although the mechanisms involved in these changes are not yet fully understood, impurity scattering in both bands seems to play a major role.…”

Section: Consequences/strategymentioning

confidence: 99%

“…In MgB 2 thermal effects should play only a minor role due to its comparatively low Ginzburg number. Nevertheless, the critical currents become too small for power applications at fields well below H c2 , even at 4.2 K. Fortunately, the upper critical field of MgB 2 can be rather easily enhanced by certain preparation conditions [1,2,3], doping [4,5,6,7,8] or irradiation [9,10,11], and exceeds 30 T (at 0 K). Even for such "high-H c2 " materials, the application range is limited to around 10 T in polycrystalline samples.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the upper critical-field anisotropy on the transport properties of polycrystalline MgB2

Eisterer

Krutzler

Weber

2005

Journal of Applied Physics

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The intrinsic properties of MgB2 form the basis for all applications of this superconductor. We wish to emphasize that the application range of polycrystalline MgB2 is limited by the upper critical field Hc2 and its anisotropy. In wires or tapes, the MgB2 grains are randomly oriented or only slightly textured and the anisotropy of the upper critical field leads to different transport properties in different grains, if a magnetic field is applied and the current transport becomes percolative. The irreversibility line is caused by the disappearance of a continuous superconducting current path and not by depinning as in high temperature superconductors. Based on a percolation model, we demonstrate how changes of the upper critical field and its anisotropy and how changes of flux pinning will influence the critical currents of a wire or a tape. These predictions are compared to results of neutron irradiation experiments, where these parameters were changed systematically.

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Section: Consequences/strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of the upper critical-field anisotropy on the transport properties of polycrystalline MgB2

Eisterer

Krutzler

Weber

2005

Journal of Applied Physics

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“…The full characterization of such samples is reported elsewhere. 6 We want to stress here that the samples whose critical temperature decreases with the neutron fluence down to 9.3 K, present very sharp transitions (see table I), indicating a homogeneous distribution of defects within the samples.…”

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confidence: 99%

Enhanced flux pinning in neutron irradiatedMgB2

et al. 2005

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We study the effect of neutron irradiation on the critical current density J c of isotopically pure polycrystalline Mg 11 B 2 samples. For fluences in the range 10 17 -10 18 cm -2 , J c is enhanced and its dependence on magnetic field is significantly improved: we demonstrate that, in this regime, pointlike pinning centers are effectively introduced in the system proportionally to the neutron fluence.Instead, for larger fluences, a strong suppression of the critical temperature accompanied by a decrease of both the upper critical field B c2 and J c is found.

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“…For instance, chemical doping can significantly enhance J c in MgB 2 , but with a considerable degradation of T c ; carbon doping can reduce T c from 39 K to nearly as low as 10 K, for carbon content up to 20% [17][18][19][20][21][22]. Similarly, the irradiation method can improve J c in MgB 2 , but it reduces T c values significantly (by more than 20 K in some cases) [23][24][25][26][27]. Correspondingly, the chemical doping and irradiation methods can also change the nature of the pinning mechanism in MgB 2 [24,[28][29][30].…”

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confidence: 99%

Hydrostatic pressure induced transition fromδT_Ctoδℓpinning mechanism in MgB₂

Shabbir¹,

Wang²,

Ghorbani³

et al. 2015

Supercond. Sci. Technol.

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The impact of hydrostatic pressure up to 1.2 GPa on the critical current density (J c ) and the nature of the pinning mechanism in MgB 2 have been investigated within the framework of the collective theory. We found that the hydrostatic pressure can induce a transition from the regime where pinning is controlled by spatial variation in the critical transition temperature (δT c ) to the regime controlled by spatial variation in the mean free path (δℓ). Furthermore, T c and low field J c are slightly reduced, although the J c drops more quickly at high fields than at ambient pressure. We found that the pressure raises the anisotropy and reduces the coherence length, resulting in weak interaction of the vortex cores with the pinning centres. Moreover, the hydrostatic pressure can reduce the density of states [N s (E)], which, in turn, leads to a reduction in the critical temperature from 39.7 K at P = 0 GPa to 37.7 K at P = 1.2 GPa.Magnesium diboride (MgB 2 ) is a promising superconducting material which can replace conventional low critical temperature (T c ) superconductors in practical applications, due to its relatively high T c of 39 K, strongly linked grains, rich multiple band structure, low fabrication cost, and especially, its high critical current density (J c ) values of 10 5 -10 6 A/cm 2 [1-9]. Numerous studies have been carried out in order to understand the vortex-pinning mechanisms in more detail, which have led to real progress regarding the improvement of J c . There are two predominant mechanisms, c pinning, which is associated with spatial fluctuations of the T c , and ℓ pinning, associated with charge carrier mean free path (ℓ) fluctuations [10][11][12][13][14].Very recently, our team have found that hydrostatic pressure is a most effective approach to enhance J c significantly in iron based superconductors, as the pressure can induce more point pinning centres and also affect the pinning mechanism [15]. Therefore, it is natural to investigate the impact of hydrostatic pressure on J c and flux pinning mechanisms in MgB 2 . Previous studies have shown that pressure of 1 GPa can reduce T c , but only by less than 2 K in MgB 2 . This is a very insignificant reduction as compared to the other approaches (i.e. chemical doping and irradiation) which are mainly used for J c enhancement [16]. For instance, chemical doping can significantly enhance J c in MgB 2 , but with a considerable degradation of T c ; carbon doping can reduce T c from 39 K to nearly as low as 10 K, for carbon content up to 20% [17][18][19][20][21][22]. Similarly, the irradiation method can improve J c in MgB 2 , but it reduces T c values significantly (by more than 20 K in some cases) [23][24][25][26][27]. Correspondingly, the chemical doping and irradiation methods can also change the nature of the pinning mechanism in MgB 2 [24,[28][29][30]. The determination of J c and the flux pinning mechanism under hydrostatic pressure is also an important step to probe the mechanism of superconductivity in more detail in MgB 2 . It is very i...

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Neutron irradiation of MgB211: From the enhancement to the suppression of superconducting properties

Abstract: Articles you may be interested inElectrical resistivity, Debye temperature, and connectivity in heavily doped bulk MgB 2 superconductors Correlation between doping induced disorder and superconducting properties in carbohydrate doped MgB 2

Cited by 75 publications

References 16 publications

Influence of the upper critical-field anisotropy on the transport properties of polycrystalline MgB2

Influence of the upper critical-field anisotropy on the transport properties of polycrystalline MgB2

Enhanced flux pinning in neutron irradiatedMgB2

Hydrostatic pressure induced transition fromδT_Ctoδℓpinning mechanism in MgB₂

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Neutron irradiation of MgB211: From the enhancement to the suppression of superconducting properties

Abstract: Articles you may be interested inElectrical resistivity, Debye temperature, and connectivity in heavily doped bulk MgB 2 superconductors Correlation between doping induced disorder and superconducting properties in carbohydrate doped MgB 2

Cited by 75 publications

References 16 publications

Influence of the upper critical-field anisotropy on the transport properties of polycrystalline MgB2

Influence of the upper critical-field anisotropy on the transport properties of polycrystalline MgB2

Enhanced flux pinning in neutron irradiatedMgB2

Hydrostatic pressure induced transition fromδTCtoδℓpinning mechanism in MgB2

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Hydrostatic pressure induced transition fromδT_Ctoδℓpinning mechanism in MgB₂