New Scaling Laws for Pinning Force Density in Superconductors

Talantsev, E. F.

doi:10.3390/condmat7040074

Cited by 5 publications

(3 citation statements)

References 85 publications

(236 reference statements)

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“…Finning force maximum, |𝐹 𝑝,𝑚𝑎𝑥 (𝐽 𝑐 , 𝐵)|, represents global maximum of the vector product of the transport critical current density, 𝐽 𝑐 ⃗⃗ , and the applied magnetic field, 𝐵 ⃗ , and it can be derived as from |𝐹 𝑝 (𝐵)| [35][36][37], as from |𝐹 𝑝 (𝐽 𝑐 )| [57] projections of the 𝐹 𝑝 (𝐽 𝑐 , 𝐵) function (Eq. 1).…”

Section: Discussionmentioning

confidence: 99%

Characteristic Length for Pinning Force Density in Nb3Sn

Talantsev¹,

Valova-Zaharevskaya²,

Deryagina³

et al. 2023

Preprint

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The pinning force density FpJc,B=Jc×B (where Jc is the critical current density and B is the applied magnetic field) is one of the main parameters that characterize the resilience of a superconductor to carry a dissipative-free transport current in an applied magnetic field. Kramer (1973 J. Appl. Phys. 44 1360), and Dew-Hughes (1974 Phil. Mag. 30 293) proposed a widely used scaling law for the pinning force density amplitude: FpB=Fp,max×p+qp+qppqq×BBc2p×1-BBc2q, where Fp,max, Bc2, p, and q are free-fitting parameters. Since the late 1970-s till now, several research groups have reported experimental data on the dependence of Fp,max on the average grain size, d, in Nb3Sn-based conductors. Godeke (2006 Supercond. Sci. Techn. 19 R68) proposed that the dependence obeys the law Fp,maxd=A×ln1d+B. However, this scaling law has several problems, for instance, the logarithm is taken from a non-dimensionless variable, and Fp,maxd&lt;0 for large grain sizes, and Fp,maxd→∞ for d→0. Here, we reanalysed the full inventory of publicly available Fp,maxd data for Nb3Sn conductors and found that the dependence can be described by Fp,maxd=Fp,max0×exp-dδ law, where the characteristic length, δ, varies within a remarkably narrow range, that is, δ=175±13 nm, for samples fabricated by different technologies. The interpretation of the result is based on the idea that the in-field supercurrent flows within a thin surface layer (thickness of δ) near the grain boundary surfaces (similar to London’s law, where the self-field supercurrent flows within a thin surface layer with a thickness of the London penetration depth, λ, and the surface is a superconductor-vacuum surface). An alternative interpretation is that δ represents the characteristic length of the exponential decay flux pinning potential from the dominant defects in Nb3Sn superconductors, which are grain boundaries.

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Section: Discussionmentioning

confidence: 99%

Characteristic Length for Pinning Force Density in Nb3Sn

Talantsev¹,

Valova-Zaharevskaya²,

Deryagina³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…In this study, we analyzed the

values deduced from the

projection [ 38 , 39 , 40 ] of the

curve. However, the same maximal values can be derived from the

[ 61 ] projections of the

curve.…”

Section: Discussionmentioning

confidence: 99%

Characteristic Length for Pinning Force Density in Nb3Sn

et al. 2023

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The pinning force density, Fp, is one of the main parameters that characterize the resilience of a superconductor to carrying a dissipative-free transport current in an applied magnetic field. Kramer (1973) and Dew-Hughes (1974) proposed a widely used scaling law for this quantity, where one of the parameters is the pinning force density maximum, Fp,max, which represents the maximal performance of a given superconductor in an applied magnetic field at a given temperature. Since the late 1970s to the present, several research groups have reported experimental data on the dependence of Fp,max on the average grain size, d, in Nb3Sn-based conductors. Fp,maxd datasets were analyzed and a scaling law for the dependence Fp,maxd=A×ln1/d+B was proposed. Despite the fact that this scaling law is widely accepted, it has several problems; for instance, according to this law, at T=4.2 K and d≥650 nm, Nb3Sn should lose its superconductivity, which is in striking contrast to experiments. Here, we reanalyzed the full inventory of publicly available Fp,maxd data for Nb3Sn conductors and found that the dependence can be described by the exponential law, in which the characteristic length, δ, varies within a remarkably narrow range of δ=175±13 nm for samples fabricated using different technologies. The interpretation of this result is based on the idea that the in-field supercurrent flows within a thin surface layer (thickness of δ) near grain boundary surfaces (similar to London’s law, where the self-field supercurrent flows within a thin surface layer with a thickness of the London penetration depth, λ, and the surface is a superconductor–vacuum surface). An alternative interpretation is that δ represents the characteristic length of the exponential decay flux pinning potential from the dominant defects in Nb3Sn superconductors, which are grain boundaries.

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“…Figure 4 shows a very good agreement between values calculated using first-principles calculations and extracted from experiment λ e−ph and characteristic phonon temperatures, T θ and The derived T F , λ e−ph , and T θ T F , values for highly compressed titanium are shown in Figures 5-7, together with values for the main superconducting families. It should be noted that other global scaling laws utilize different variables [83,[134][135][136][137][138][139][140].…”

Section: Highly Compressed Titaniummentioning

confidence: 99%

Quantifying the Nonadiabaticity Strength Constant in Recently Discovered Highly Compressed Superconductors

Talantsev

2023

Symmetry

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Superconductivity in highly pressurized hydrides has become the primary direction for the exploration of the fundamental upper limit of the superconducting transition temperature, Tc, after Drozdov et al. (Nature 2015, 525, 73) discovered a superconducting state with Tc=203 K in highly compressed sulfur hydride. To date, several dozen high-temperature superconducting polyhydrides have been discovered and, in addition, it was recently reported that highly compressed titanium and scandium exhibit record-high Tc (up to 36 K). This exceeded the Tc=9.2 K value of niobium many times over, which was the record-high Tc ambient pressure metallic superconductor. Here, we analyzed the experimental data for the recently discovered high-pressure superconductors (which exhibit high transition temperatures within their classes): elemental titanium (Zhang et al., Nature Communications 2022; Liu et al., Phys. Rev. B 2022), TaH3 (He et al., Chinese Phys. Lett. 2023), LaBeH8 (Song et al., Phys. Rev. Lett. 2023), black phosphorous (Li et al., Proc. Natl. Acad. Sci. 2018; Jin et al., arXiv 2023), and violet (Wu et al., arXiv 2023) phosphorous to reveal the nonadiabaticity strength constant TθTF (where Tθ is the Debye temperature, and TF the Fermi temperature) in these superconductors. The analysis showed that the δ-phase of titanium and black phosphorous exhibits TθTF scores that are nearly identical to those associated with A15 superconductors, while the studied hydrides and violet phosphorous exhibit constants in the same ballpark as those of H3S and LaH10.

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New Scaling Laws for Pinning Force Density in Superconductors

Cited by 5 publications

References 85 publications

Characteristic Length for Pinning Force Density in Nb3Sn

Characteristic Length for Pinning Force Density in Nb3Sn

Characteristic Length for Pinning Force Density in Nb3Sn

Quantifying the Nonadiabaticity Strength Constant in Recently Discovered Highly Compressed Superconductors

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