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Advances in Superconducting Materials: Characterization, Properties and Applications

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Quantum Materials".

Deadline for manuscript submissions: closed (10 July 2023) | Viewed by 19343

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Special Issue Editor

Prof. Dr. Yong Seung Kwon

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Guest Editor

Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873, Republic of Korea
Interests: superconducting materials; single crystal growth; FT-IR spectroscopy; vortex dynamics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The discovery of superconductivity in cuprates and iron-based superconductors has led to explosive growth driven by the quest for higher and higher superconducting transition temperatures. In the early stages, there was tremendous excitement in both physical science and engineering. However, the complexity of the new material on the one hand and the absence of a viable theory on the other made further development even more difficult. Therefore, the excitement of the initial period and its rapid development have opened the way for a more systematic and detailed study of all aspects of superconductivity and are expected to continue. This Special Issue is intended to provide an opportunity to review progress in selected superconducting fields. Emphasis is placed on experimental and theoretical studies of new superconductors, advances in theoretical understanding, advances in flux pinning and vortex dynamics studies affecting critical currents, and development of new methods of material synthesis.

Dr. Yong Seung Kwon
Guest Editor

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Keywords

experimental and theoretical studies of new superconductors
advances in experimental results (electrical, thermal, magnetic, optical)
advances in theoretical understanding
development of new methods of superconducting relative material synthesis
advances in flux pinning and vortex dynamics studies
coexistence or competition of superconductivity with other orders

Related Special Issue

Advances in Superconducting Materials: Characterization, Properties and Applications (Second Edition) in Materials

Published Papers (10 papers)

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Research

14 pages, 2937 KiB

Open AccessArticle

Characteristic Length for Pinning Force Density in Nb₃Sn

by Evgeny F. Talantsev, Evgeniya G. Valova-Zaharevskaya, Irina L. Deryagina and Elena N. Popova

Materials 2023, 16(14), 5185; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16145185 - 24 Jul 2023

Viewed by 905

Abstract

The pinning force density,

F_{p}

, 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 [...] Read more.

The pinning force density,

F_{p}

F_{p, m a x}

, 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

F_{p, m a x}

on the average grain size,

d

, in Nb₃Sn-based conductors.

F_{p, m a x} (d)

datasets were analyzed and a scaling law for the dependence

|F_{p, m a x} (d)| = A \times l n (1 / 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 \geq 650 nm

, Nb₃Sn should lose its superconductivity, which is in striking contrast to experiments. Here, we reanalyzed the full inventory of publicly available

F_{p, m a x} (d)

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 \pm 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. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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15 pages, 3276 KiB

Open AccessArticle

One- and Two-Particle Correlation Functions in the Cluster Perturbation Theory for Cuprates

by Valerii I. Kuz’min, Sergey V. Nikolaev, Maxim M. Korshunov and Sergey G. Ovchinnikov

Materials 2023, 16(13), 4640; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16134640 - 27 Jun 2023

Cited by 1 | Viewed by 709

Abstract

The physics of high-

T_{c}

The physics of high-

T_{c}

superconducting cuprates is obscured by the effect of strong electronic correlations. One way to overcome this problem is to seek an exact solution at least within a small cluster and expand it to the whole crystal. Such an approach is at the heart of cluster perturbation theory (CPT). Here, we developed CPT for the dynamic spin and charge susceptibilities (spin-CPT and charge-CPT), with the correlation effects explicitly taken into account by the exact diagonalization. We applied spin-CPT and charge-CPT to the effective two-band Hubbard model for the cuprates obtained from the three-band Emery model and calculated one- and two-particle correlation functions, namely, a spectral function and spin and charge susceptibilities. The doping dependence of the spin susceptibility was studied within spin-CPT and CPT-RPA, that is, the CPT generalization of the random phase approximation (RPA). In the underdoped region, both our methods resulted in the signatures of the upper branch of the spin excitation dispersion with the lowest excitation energy at the

(π, π)

wave vector and no presence of low-energy incommensurate excitations. In the high doping region, both methods produced a low energy response at four incommensurate wave vectors in qualitative agreement with the results of the inelastic neutron scattering experiments on overdoped cuprates. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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12 pages, 1427 KiB

Open AccessEditor’s ChoiceArticle

Critical Current Density in d-Wave Hubbard Superconductors

by José Samuel Millán, Jorge Millán, Luis A. Pérez and Harold S. Ruiz

Materials 2022, 15(24), 8969; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15248969 - 15 Dec 2022

Viewed by 1663

Abstract

In this work, the Generalized Hubbard Model on a square lattice is applied to evaluate the electrical current density of high critical temperature d-wave superconductors with a set of Hamiltonian parameters allowing them to reach critical temperatures close to 100 K. The appropriate set of Hamiltonian parameters permits us to apply our model to real materials, finding a good quantitative fit with important macroscopic superconducting properties such as the critical superconducting temperature (

T_{c}

) and the critical current density

(J_{c})

. We propose that much as in a dispersive medium, in which the velocity of electrons can be estimated by the gradient of the dispersion relation

\nabla ε (k)

, the electron velocity is proportional to

\nabla E (k)

in the superconducting state (where

E (k) = \sqrt{{(ε (k) - μ)}^{2} + Δ^{2} (k)}

is the dispersion relation of the quasiparticles, and k is the electron wave vector). This considers the change of

ε (k)

with respect to the chemical potential (

μ

) and the formation of pairs that gives rise to an excitation energy gap

Δ (k)

in the electron density of states across the Fermi level. When

ε (k) = μ

at the Fermi surface (FS), only the term for the energy gap remains, whose magnitude reflects the strength of the pairing interaction. Under these conditions, we have found that the d-wave symmetry of the pairing interaction leads to a maximum critical current density in the vicinity of the antinodal k-space direction

(π, 0)

of approximately

1.407236 \times 10^{8}

A/cm², with a much greater current density along the nodal direction

(\frac{π}{2}, \frac{π}{2})

2.214702 \times 10^{9}

A/cm². These results allow for the establishment of a maximum limit for the critical current density that could be attained by a d-wave superconductor. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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16 pages, 9579 KiB

Open AccessEditor’s ChoiceArticle

Effect of Silver Doping on the Superconducting and Structural Properties of YBCO Films Grown by PLD on Different Templates

by Ilya A. Shipulin, Aleena Anna Thomas, Sigrid Holleis, Michael Eisterer, Kornelius Nielsch and Ruben Hühne

Materials 2022, 15(15), 5354; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15155354 - 03 Aug 2022

Cited by 2 | Viewed by 1898

Abstract

We report the local structural and superconducting properties of undoped and Ag-doped YBa₂Cu₃O_6+x (YBCO) films with a thickness of up to 1 µm prepared by pulsed laser deposition on SrTiO₃ (STO) single crystals and on ion-beam-assisted deposition (IBAD) and rolling-assisted biaxially textured substrate (RABiTS)-based metal templates. X-ray diffraction demonstrates the high crystalline quality of the films on both single crystalline substrates and metal-based templates, respectively. Although there was only a slight decrease in T_c of up to 1.5 K for the Ag-doped YBCO films on all substrates, we found significant changes in their transport characteristics. The effect of the silver doping mainly depended on the concentration of silver, the type of substrate, and the temperature and magnetic field. In general, the greatest improvement in J_c over a wide range of magnetic fields and temperatures was observed for the 5%Ag-doped YBCO films on STO substrates, showing a significant increase compared to undoped films. Furthermore, a slight J_c improvement was observed for the 2%Ag-doped YBCO films on the RABiTS templates at temperatures below 65 K, whereas J_c decreased for the Ag-doped films on IBAD-MgO-based templates compared to undoped YBCO films. Using detailed electron microscopy studies, small changes in the local microstructure of the Ag-doped YBCO films were revealed; however, no clear correlation was found with the transport properties of the films. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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10 pages, 766 KiB

Open AccessEditor’s ChoiceArticle

Pressure Tuning of Superconductivity of LaPt₄Ge₁₂ and PrPt₄Ge₁₂ Single Crystals

by Gustavo A. Lombardi, Kamal Mydeen, Roman Gumeniuk, Andreas Leithe-Jasper, Walter Schnelle, Ricardo D. dos Reis and Michael Nicklas

Materials 2022, 15(8), 2743; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15082743 - 08 Apr 2022

Cited by 1 | Viewed by 1510

Abstract

We carried out electrical resistivity and X-ray diffraction (XRD) studies on the filled skutterudite superconductors LaPt

_{4}

_{12}

and PrPt

_{4}

_{12}

under hydrostatic pressure. The superconducting transition temperature

T_{c}

is linearly suppressed upon increasing pressure, though the effect of [...] Read more.

We carried out electrical resistivity and X-ray diffraction (XRD) studies on the filled skutterudite superconductors LaPt

_{4}

_{12}

and PrPt

_{4}

_{12}

under hydrostatic pressure. The superconducting transition temperature

T_{c}

is linearly suppressed upon increasing pressure, though the effect of pressure on

T_{c}

is rather weak. From the analysis of the XRD data, we obtain bulk moduli of

B = 106

GPa and

B = 83

GPa for LaPt

_{4}

_{12}

and PrPt

_{4}

_{12}

, respectively. The knowledge of the bulk modulus allows us to compare the dependence of

T_{c}

on the unit-cell volume from our pressure study directly with that found in the substitution series La

_{1 - x}

_{x}

_{4}

_{12}

. We find that application of hydrostatic pressure can be characterized mainly as a volume effect in LaPt

_{4}

_{12}

and PrPt

_{4}

_{12}

, while substitution of Pr for La in La

_{1 - x}

_{x}

_{4}

_{12}

yields features going beyond a simple picture. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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11 pages, 2140 KiB

Open AccessArticle

Critical Current Density and Meissner Effect of Smart Meta-Superconductor MgB₂ and Bi(Pb)SrCaCuO

by Honggang Chen, Yongbo Li, Yao Qi, Mingzhong Wang, Hongyan Zou and Xiaopeng Zhao

Materials 2022, 15(3), 972; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15030972 - 27 Jan 2022

Cited by 3 | Viewed by 2534

Abstract

The smart meta-superconductor MgB₂ and Bi(Pb)SrCaCuO increase the superconducting transition temperature (T_C), but the changes in the transport critical current density (J_C) and Meissner effect are still unknown. Here, we investigated the J_C and Meissner effect of smart meta-superconductor MgB₂ and Bi(Pb)SrCaCuO. The use of the standard four-probe method shows that Y₂O₃:Eu³⁺ and Y₂O₃:Eu³⁺+Ag inhomogeneous phase significantly increase the J_C, and J_C decreases to a minimum value at a higher temperature. The Meissner effect was measured by direct current magnetization. The doping of Y₂O₃:Eu³⁺ and Y₂O₃:Eu³⁺+Ag luminescent inhomogeneous phase causes a Meissner effect of MgB₂ and Bi(Pb)SrCaCuO at a higher temperature, while the non-luminescent dopant reduces the temperature at which samples have Meissner effect. The introduction of luminescent inhomogeneous phase in conventional MgB₂ and copper oxide high-temperature Bi(Pb)SrCaCuO superconductor increases the T_C and J_C, and Meissner effect is exerted at higher temperature. Therefore, smart meta-superconductivity is suitable for conventional and copper oxide high-temperature superconductors. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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14 pages, 4252 KiB

Open AccessArticle

Numerical Modelling of the Dynamic Voltage in HTS Materials under the Action of DC Transport Currents and Different Oscillating Magnetic Fields

by Boyang Shen, Xiaoyuan Chen, Lin Fu, Luning Hao and Tim Coombs

Materials 2022, 15(3), 795; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15030795 - 21 Jan 2022

Cited by 8 | Viewed by 1632

Abstract

The dynamic voltage is a unique phenomenon of superconducting materials. It arises when the superconductor is carrying a DC transport current and spontaneously in subject to an AC magnetic field. This study excavates the aspects that previous studies have not comprehensively investigated: the dynamic voltage in a DC-carrying superconducting tape exposed to different oscillating AC magnetic fields. First, the fundamental physics of dynamic voltage/flux of superconductors is reviewed and further analysed in detail. We used the superconducting modelling method using the H-formulation merged into the finite-element method (FEM) software, to re-produce the typical dynamic voltage behaviour of a superconducting tape. The modelling was verified by both the analytical and experimental results, in order to precisely prove the reliability of the modelling. Afterwards, the modelling was performed for a DC-carrying superconducting tape under four different oscillating magnetic fields (sine, triangle, sawtooth and square), and their corresponding dynamic voltages and energy losses were analysed and compared. Results show the sinusoidal magnetic field can lead to the optimal combination of reasonable dynamic voltage but relatively lower loss, which is suitable for those superconducting applications requiring dynamic voltage as the energy source, e.g., flux pumps. This article presents novel investigation and analysis of the dynamic voltage in superconducting materials, and both the methodology and results can provide useful information for the future design/analysis of superconducting applications with DC transport currents and AC magnetic fields. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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8 pages, 866 KiB

Open AccessEditor’s ChoiceArticle

Pseudogap Isotope Effect as a Probe of Bipolaron Mechanism in High Temperature Superconductors

by Victor D. Lakhno

Materials 2021, 14(17), 4973; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14174973 - 31 Aug 2021

Cited by 1 | Viewed by 1814

Abstract

A theory of a pseudogap phase of high-temperature superconductors where current carriers are translation invariant bipolarons is developed. A temperature

T^{*}

of a transition from a pseudogap phase to a normal one is calculated. For the temperature of a transition to the [...] Read more.

A theory of a pseudogap phase of high-temperature superconductors where current carriers are translation invariant bipolarons is developed. A temperature

T^{*}

of a transition from a pseudogap phase to a normal one is calculated. For the temperature of a transition to the pseudogap phase, the isotope coefficient is found. It is shown that the results obtained, in particular, the possibility of negative values of the isotope coefficient, are consistent with the experiment. New experiments on the influence of the magnetic field on the isotope coefficient are proposed. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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11 pages, 2336 KiB

Open AccessEditor’s ChoiceArticle

Classifying Charge Carrier Interaction in Highly Compressed Elements and Silane

by Evgueni F. Talantsev

Materials 2021, 14(15), 4322; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14154322 - 02 Aug 2021

Cited by 3 | Viewed by 1954

Abstract

Since the pivotal experimental discovery of near-room-temperature superconductivity (NRTS) in highly compressed sulphur hydride by Drozdov et al. (Nature 2015, 525, 73–76), more than a dozen binary and ternary hydrogen-rich phases exhibiting superconducting transitions above 100 K have been discovered to date. There is a widely accepted theoretical point of view that the primary mechanism governing the emergence of superconductivity in hydrogen-rich phases is the electron–phonon pairing. However, the recent analysis of experimental temperature-dependent resistance, R(T), in H₃S, LaH_x, PrH₉ and BaH₁₂ (Talantsev, Supercond. Sci. Technol. 2021, 34, accepted) showed that these compounds exhibit the dominance of non-electron–phonon charge carrier interactions and, thus, it is unlikely that the electron–phonon pairing is the primary mechanism for the emergence of superconductivity in these materials. Here, we use the same approach to reveal the charge carrier interaction in highly compressed lithium, black phosphorous, sulfur, and silane. We found that all these superconductors exhibit the dominance of non-electron–phonon charge carrier interaction. This explains the failure to demonstrate the high-T_c values that are predicted for these materials by first-principles calculations which utilize the electron–phonon pairing as the mechanism for the emergence of their superconductivity. Our result implies that alternative pairing mechanisms (primarily the electron–electron retraction) should be tested within the first-principles calculations approach as possible mechanisms for the emergence of superconductivity in highly compressed lithium, black phosphorous, sulfur, and silane. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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11 pages, 2499 KiB

Open AccessEditor’s ChoiceArticle

Reinforcing Increase of ΔT_c in MgB₂ Smart Meta-Superconductors by Adjusting the Concentration of Inhomogeneous Phases

by Yongbo Li, Guangyu Han, Hongyan Zou, Li Tang, Honggang Chen and Xiaopeng Zhao

Materials 2021, 14(11), 3066; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14113066 - 04 Jun 2021

Cited by 6 | Viewed by 2650

Abstract

Incorporating with inhomogeneous phases with high electroluminescence (EL) intensity to prepare smart meta-superconductors (SMSCs) is an effective method for increasing the superconducting transition temperature (T_c) and has been confirmed in both MgB₂ and Bi(Pb)SrCaCuO systems. However, the increase of ΔT_c (ΔT_c = T_c ‒ T_cpure) has been quite small because of the low optimal concentrations of inhomogeneous phases. In this work, three kinds of MgB₂ raw materials, namely, ^aMgB₂, ^bMgB₂, and ^cMgB₂, were prepared with particle sizes decreasing in order. Inhomogeneous phases, Y₂O₃:Eu³⁺ and Y₂O₃:Eu³⁺/Ag, were also prepared and doped into MgB₂ to study the influence of doping concentration on the ΔT_c of MgB₂ with different particle sizes. Results show that reducing the MgB₂ particle size increases the optimal doping concentration of inhomogeneous phases, thereby increasing ΔT_c. The optimal doping concentrations for ^aMgB₂, ^bMgB₂, and ^cMgB₂ are 0.5%, 0.8%, and 1.2%, respectively. The corresponding ΔT_c values are 0.4, 0.9, and 1.2 K, respectively. This work open a new approach to reinforcing increase of ΔT_c in MgB₂ SMSCs. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: Characterization, Properties and Applications)

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