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Presented are classroom activities in which students explore the potential use of magnetic levitation for transportation purposes. The advantages of using a MagLev transportation system instead of conventional trains are discussed. Directions for designing and building a MagLev track and circuit are provided. (KR)

Discusses the principles of magnetic levitation presented in the physics classroom and applied to transportation systems. Topics discussed include three classroom demonstrations to illustrate magnetic levitation, the concept of eddy currents, lift and drag forces on a moving magnet, magnetic levitation vehicles, levitation with permanent magnets and superconductors, and magnetic bearings. (MDH)

Describes the history and the development of the field of superconductivity. Identifies the significant interaction of electrons to form Cooper pairs. Presents background theory, describes approaches, and discusses problems encountered in the search for better high temperature superconducting materials. Provides technological applications of superconductors to technology. (PR)

The introduction of the quantum standards of resistance and voltage, based on the Quantum Hall Effect (QHE) and the Josephson Effect, can be used to establish highly reproducible and uniform representations of the ohm and volt worldwide. Discussed are the QHE and the Josephson Effect. (KR)

Discusses superconducting microelectronics based on the Josephson effect and its advantages over conventional integrated circuits in speed and sensitivity. Considers present uses in standards laboratories (voltage) and in measuring weak magnetic fields. Also considers future applications in superfast computer circuitry using Superconducting Quantum Interference Devices (SQUIDS) as switching units. (JM)

Outlined is the history of superconductivity and described are the physical and chemical principles upon which it rests. Some possible applications of superconductors are considered. (RH)

Described is a student preparation of YBa2Cu3O8-x, a classroom demonstration of its superconductivity, and an analytical chemistry experiment dealing with the oxidation state of copper in the material. (RH)

Describes how to make a superconducting pellet for classroom use. Details two tests that can use the pellet to demonstrate superconductivity. Discusses some of the mechanics and chemistry of superconductivity. Lists materiads and equipment necessary for these activities. (CW)

Describes the new class of oxide superconductors, the importance of these materials, and the concepts that led to its discovery. Summarizes the discovery itself and its early confirmation. Discusses the observation of a superconductive glass state in percolative samples. (TW)

Described is the manufacture of a superconductor from a commercially available kit using equipment usually available in schools or easily obtainable. The construction is described in detail including equipment, materials, safety procedures, tolerances, and manufacture. (Author/CW)

Presented are the materials and a procedure for demonstrating the levitation of a magnet above a superconducting material. The demonstration can be projected with an overhead projector for a large group of students. Kits to simplify the demonstration can be purchased from the Institute for Chemical Education of the University of Wisconsin-Madison. (RH)

Includes four articles: "Virtual Reality" (Kopf), description of its uses in computer-assisted design, architecture, and technical training; "SME (Society of Manufacturing Engineers) Robotics Contest Opens Doors to Future" (Wagner); "Superconductivity" (Canady), description of classroom demonstrations and experiments; and "Factories of the Future" (Applegate), use of computer workstations in semiconductor manufacturing. (SK)

Discusses the trends in employment in the electrical/electronics (E/E) engineering industry. States that although the number of E/E graduates grew at a rate of over 11 percent from 1985 to 1986, the economy continues to be the major determinant in the job outlook in the field. (TW)

Shows that the mutual repulsion that enables a superconductor to levitate a magnet and a magnet to levitate a superconductor can be combined into a single demonstration. Uses an overhead projector, two pellets of "1-2-3" superconductor, Nd-Fe-B magnets, liquid nitrogen, and paraffin. Offers superconductor preparation, hazards, and disposal methods. (MVL)

Describes the "Project 1-2-3" levitation kit used to demonstrate superconductivity. Summarizes the materials included in the kit. Discusses the effect demonstrated and gives details on how to obtain kits. Gives an overview of the documentation that is included. (CW)

The discovery of a superconducting organic compound is reported. The compound, (TMTSF)-2, has no metal in its composition, and the author believes that it is the precursor of a family of superconducting organics. (Author/SA)

In our article, we show the n value determined from measurements using the magnetic field sweep method (curves of E from B/Bc) and the current sweep method (curves of E from I/Ic). The results from these two methods allowed for a scientific n value analysis. Moreover, measurements using these two methods allow for a better understanding of the behavior of superconducting wires after the transition from the superconducting state to the normal (resistive) state. Measurements were made for the NbTi wire at 4.2 K, MgB2 at the temperature range from 4.2 to 30 K, and high-temperature superconducting tape at 77 K. The magnetic field sweep method results show that the n value has a constant value independent of an increase in the magnetic field, number of filaments, type of boron, diameter of the wire, and small amount of the dopant. Moreover, research studies point out that the n value in the magnetic field sweep method depends on the type of superconductor material, a large amount of doping at high temperatures, and the low density of pinning centers. Based on the results obtained, it can be indicated that each superconducting material will have a constant n value. Measurements carried out using the current sweep method showed that the n value decreases significantly with an increase in the magnetic field. Moreover, research studies have shown that the n value depends on the number of filaments, type of boron, dopant, wire diameter, and temperature. On this basis, it can be indicated that the n value for the current sweep method depends on the morphology and structure of the superconducting wires. In addition, based on the samples measured in this research, the current sweep method allows for higher n values than the magnetic field sweep method in low magnetic fields. However, the magnetic field sweep method allows obtaining higher n values than the current sweep method in middle and high magnetic fields. [ABSTRACT FROM AUTHOR]

We investigate the effects of the circularly polarized light (CPL) and the electric field (EF) on the nonlocal transport in a silicene-based antiferromagnet/superconductor/ferromagnet (AF/S/F) asymmetrical junction. For case I (II), the CPL and the EF are applied simultaneously in the antiferromagnetic (ferromagnetic) region, whereas in the ferromagnetic (antiferromagnetic) region, only a constant EF is considered. The spin-valley-resolved conductance can be turned on or off by adjusting the CPL or the EF. The AF/S/F junction can be manipulated as a spin-locked valley filter for case I, while for case II, it can be used not only as a valley-locked spin filter but also as a nonlocal switch between two pure nonlocal processes. Such interesting nonlocal switch effect can be effectively controlled by reversing the direction of the incident energy axis, the handedness of the CPL, or the direction of the EF. These findings may open an avenue to the design and manufacture of the spintronic and valleytronic devices based on the asymmetrical silicene magnetic superconducting heterostructure. [ABSTRACT FROM AUTHOR]

The reversible quantum-flux-parametron (RQFP) is a reversible logic gate based on an energy-efficient superconductor logic family, namely, the adiabatic quantum-flux-parametron logic. The RQFP can perform logic operations in a thermodynamically reversible manner (i.e., without energy dissipation) in the quasi-static limit due to its logical and physical reversibility. Hence, it can be used for investigating the fundamental relations between information and thermodynamics from a circuit perspective. In the present study, we propose a reversible flip-flop (RFF) comprising an RQFP and investigate the minimum energy dissipation required for general information processing through numerical simulation using an RFF-based circuit. This circuit includes fundamental information processing (combinational logic, sequential logic, and data erasure) and can, thus, be used as a physical model for such an investigation. The numerical simulation of this circuit shows that both combinational and sequential logic operations can be conducted without energy dissipation in the quasi-static limit and that the amount of erased data determines the minimum energy dissipation. These results indicate that general information processing can be conducted in a thermodynamically reversible manner by using RQFP circuits as long as all data, including garbage outputs, are conserved. [ABSTRACT FROM AUTHOR]

Boron-based compounds have triggered substantial attention due to their multifunctional properties, incorporating excellent hardness and superconductivity. While tetragonal metal borides LiB4 and NaB4 with BaAl4-type structure and striking clathrate boron motif have been induced under compression, there is still a lack of deep understanding of their potential properties at ambient pressure. We herein conduct a comprehensive study on I4/mmm-structured LiB4 and NaB4 under ambient pressure via first-principles calculations. Remarkably, both LiB4 and NaB4 are found to possess high Vickers hardness of 39 GPa, which is ascribed to the robust boron framework with strong covalency. Furthermore, their high hardness values together with distinguished stability make them highly potential superhard materials. Meanwhile, electron–phonon coupling analysis reveals that both LiB4 and NaB4 are conventional phonon-mediated superconductors, with critical temperatures of 6 and 8 K at 1 atmosphere pressure (atm), respectively, mainly arising from the coupling of B 2p electronic states and the low-frequency phonon modes associated with Li-, Na-, and B-derived vibrations. This work provides valuable insights into the mechanical and superconducting behaviors of metal borides and will boost further studies of emergent borides with multiple functionalities. [ABSTRACT FROM AUTHOR]

Boron-based compounds have triggered substantial attention due to their multifunctional properties, incorporating excellent hardness and superconductivity. While tetragonal metal borides LiB4 and NaB4 with BaAl4-type structure and striking clathrate boron motif have been induced under compression, there is still a lack of deep understanding of their potential properties at ambient pressure. We herein conduct a comprehensive study on I4/mmm-structured LiB4 and NaB4 under ambient pressure via first-principles calculations. Remarkably, both LiB4 and NaB4 are found to possess high Vickers hardness of 39 GPa, which is ascribed to the robust boron framework with strong covalency. Furthermore, their high hardness values together with distinguished stability make them highly potential superhard materials. Meanwhile, electron–phonon coupling analysis reveals that both LiB4 and NaB4 are conventional phonon-mediated superconductors, with critical temperatures of 6 and 8 K at 1 atmosphere pressure (atm), respectively, mainly arising from the coupling of B 2p electronic states and the low-frequency phonon modes associated with Li-, Na-, and B-derived vibrations. This work provides valuable insights into the mechanical and superconducting behaviors of metal borides and will boost further studies of emergent borides with multiple functionalities. [ABSTRACT FROM AUTHOR]

As the main merits, self-stabilization and no magnetic resistance make the high-temperature superconducting (HTS) magnetic levitation technology a crucial area for high-speed magnetic levitation development. To guarantee a stable operation of superconducting magnetic levitation systems, the dynamic characteristics of superconducting bulk materials occupy a significant place. However, in the previous research, there is still a lack of a simulation method that can describe 6 degree of freedom (DOF) motion of the superconductor. In this paper, an electromagnetic–thermal–dynamic coupling calculation model was established first. Then, the damping characteristics of 5-DOF superconducting levitation were experimentally tested, and the response analysis of the superconductor under 1–20 Hz excitation was carried out to explore the coupled motion relationship between the various degrees of freedom of the superconductor. In addition to the above, the operating conditions and primary resonance intervals that should be avoided by the HTS maglev system were identified. Additionally, a numerical simulation was conducted to investigate the dynamic response of the HTS maglev system under impact loads. All in all, this study explored the temperature rise conditions of superconducting bulk materials under excitation force through magnetic-thermal-force multi-physics coupling research. This 6-DOF model can provide a comprehensive simulation method for superconducting maglev systems in superconductor's motion behavior, attitude, and thermal state monitoring. [ABSTRACT FROM AUTHOR]

This study presents an approach to achieve a triaxial magnetic alignment through a linear drive type of modulated rotating magnetic field by using a permanent magnet array. This magnet array generates a modulated rotating magnetic field (MRF) without moving the sample and can produce an MRF of ∼ 0.8 T. By utilizing this magnet array, DyBa2Cu3Oy (Dy123, y ∼ 7) grains were biaxially aligned. After cutting the as-aligned sample that was magnetically aligned, we observed a location dependence of the orientation degree. We achieved the higher in-plane orientation degree of ∼ 8.5° and the c-axis orientation degree of ∼ 6.0°, respectively. The 3D simulation analysis played a key role in identifying the region where the uniformity of the MRF is within the magnet array. Compared to the epitaxial growth techniques, the use of the magnet array offers a cost-effective and versatile solution for achieving triaxial magnetic alignment. [ABSTRACT FROM AUTHOR]

In recent years, the implementation of thin-film Ta has led to improved coherence times in superconducting circuits. Efforts to further optimize this materials set have become a focus of the subfield of materials for superconducting quantum computing. It has been previously hypothesized that grain size could be correlated with device performance. In this work, we perform a comparative grain size experiment with α -Ta on c axis sapphire. Our evaluation methods include both room-temperature chemical and structural characterization and cryogenic microwave measurements, and we report no statistical difference in device performance between smaller- and larger-grain-size devices with grain sizes of 924 and 1700 nm 2 , respectively. These findings suggest that grain size is not correlated with loss in the parameter regime of interest for Ta grown on c axis sapphire, narrowing the parameter space for optimization of this materials set. [ABSTRACT FROM AUTHOR]

The connection between the long-range antiferromagnetic order in cuprates and the high-temperature superconductivity is a scientific problem that has yet to be solved after nearly four decades. The properties and difficulties of describing nickelate superconductors are similar to those of cuprates. Recently, Fowlie et al. [Nat. Phys. 18, 1043 (2022)] aimed to detect the antiferromagnetic order in R1−xSrxNiO2 (R = Nd, Pr, La; x ∼ 0, 0.2) films by using the muon spin rotation (μSR) technique. The research group reported the presence of short-range antiferromagnetic order in every nickelate studied. Here, our goal was to prove that this interaction is present in the nickelate films. We did this by analyzing the temperature dependent resistivity, ρ(T), data from the research group. Global ρ(T) data fits to the advanced Bloch–Grüneisen model showed that each of the R1−xSrxNiO2 compounds can be characterized by a unique power-law exponent, p (where p = 2 for the electron–electron scattering, p = 3 for the electron–magnon scattering, and p = 5 for the electron–phonon scattering), and global characteristic temperature, Tω (which has the meaning of the Debye temperature at p = 5). We found that p = 2.0 in Nd- and Pr-based compounds and p = 1.3 for La-based compounds. The latter value does not have any interpretation within established theoretical models. We also analyzed ρ(T) data for Nd1–xSrxNiO2 (0.125 ≤ x ≤ 0.325) reported by Lee et al. [Nature 619, 288 (2023)]. Our analysis of nickelates led us to conclude that a new theoretical model is needed to describe ρ(T) in materials exhibiting a short-range antiferromagnetic order. [ABSTRACT FROM AUTHOR]

Analytical instruments or scientific instruments are indispensable for scientific research and industry. The analytical instruments require a detector that converts physical quantities to be measured (measurands) to electric signals. This Tutorial describes the basics of quantum and thermal detectors, the operation principles of superconductor detectors, and the ultimate performance of state-of-art analytical instruments with superconductivity. We still face fundamental issues, such as the classical Fano factor, the relation between energy gap and mean carrier creation energy, quasiparticle dynamics, and the intermediate state in the middle of superconducting transition; and engineering issues, such as the small sensitive area and the spatially nonuniform response. Nevertheless, enormous efforts have matured superconductor detectors, which enables us to solve the inherent problems of conventional analytical instruments. As an example of the analytical results, we describe x-ray spectroscopy and mass spectrometry at our institute by using three detector types: superconductor tunnel junction, transition edge sensor, and superconductor strip. Microwave kinetic inductance and metallic magnetic calorimetric types are also described. The analytical results may contribute to a wide range of fields, such as dentistry, molecular biology, energy-saving society, planetary science, and prebiotic organic molecules in space. [ABSTRACT FROM AUTHOR]

Thermal switching by magnetic fields is one of the important functionalities in thermal management technologies. In low-temperature devices, superconducting states can be used as a magneto-thermal-switching (MTS) component because carrier thermal conductivity (κ) is strongly suppressed in superconducting states. Recently, we demonstrated that the MTS ratio (MTSR) of pure Nb reached 650% at a temperature (T) of 2.5 K under a magnetic field (H) of 4.0 kOe [Yoshida et al., Appl. Phys. Express 16, 033002 (2023)]. In this study, to enrich knowledge on MTS of superconductors, the MTSRs of pure Pb wires with 5 N and 3 N purities were investigated by measuring the temperature or magnetic-field dependences of κ. For 5N-Pb, a large MTSR exceeding 1000% was observed below 3.6 K under H > 600 Oe. Although higher MTSRs were expected at lower temperatures under H > 600 Oe, the obtained data under those conditions were accompanied by large errors due to magnetic-field-induced huge κ at low temperatures. In contrast, the κ for 3N-Pb was observed to be clearly lower than that for 5N-Pb. Although the magnetic-field-induced change in κ was small, the MTSR at T = 2.5 K was 300%. These results suggest that Pb is a promising material for low-temperature magneto-thermal switching because of wide-range κ tunable by magnetic field and purity. [ABSTRACT FROM AUTHOR]

A simplified model of anisotropic magnetic susceptibility in the Meissner–London vortex-free state of cuboidal superconducting samples is presented. Using this model, precision measurements of the magnetic response in three perpendicular directions of a magnetic field with respect to primary crystal axes can be used to extract the components of the London penetration depth, thus enabling the evaluation of the general superfluid density tensor, which is needed in the analysis of the superconducting gap structure. [ABSTRACT FROM AUTHOR]

Recently, a debate is raising the concern of possible carbonaceous sulfur hydrides with room-temperature superconductivity around 270 GPa. In order to systematically investigate the structural information and relevant natures of C–S–H superconductors, we performed an extremely extensive structure search and first-principles calculations under high pressures. As a result, the metastable stoichiometries of CSH7, C2SH14, CS2H10, and CS2H11 were unveiled under high pressure, which can be viewed as CH4 units inserted into the S–H framework. Given the super-high superconductivity of Im 3 ̄ m-SH3, we performed electron–phonon coupling calculations of these compounds,the metastable of R3m-CSH7, Cm-CSH7, Cm-CS2H10, P3m1-CS2H10, Cm-CS2H11, and Fmm2-CS2H11 are predicted to become good phonon-mediated superconductors that could reach Tc of 130, 120, 72, 74, 92, and 70 K at 270 GPa, respectively. Furthermore, we identified that high Tc is associated with the large contribution of the S–H framework to the electron density of states near the Fermi level. Our results highlight the importance of the S–H framework in superconductivity and verify that the suppression of density of states of these carbonaceous sulfur hydrides by CH4 units results in Tc lower than that of Im 3 ̄ m-SH3, which could act as a useful guidance in the design and optimization of high-Tc superconductors in these and related systems. [ABSTRACT FROM AUTHOR]

Nb3Sn is a promising thin film material for superconducting radio frequency (SRF) applications. Although surface resistivity, critical temperature, and critical field are advantageous in comparison to pure Nb, currently the performance of Nb3Sn is lacking behind due to its complex defect structure and phase inhomogeneities. In this work, the influence of the kinetic energy of the deposited particles on the defect structure in Nb3Sn thin films synthesized at low temperatures is investigated. A combination of extended x-ray absorption fine structure analysis, x-ray absorption spectroscopy mapping, and transmission electron microscopy reveals an improved local order and elemental homogeneity of the Nb3Sn films induced by higher kinetic energies of the elemental species during deposition. Even more, these process conditions lead to suppressed local inhomogeneities at grain boundaries, which can be one of the causes of critically reduced superconducting properties of low temperature sputter-coated Nb3Sn thin films. Finally, we show that the magnetic field-induced reduction of critical currents across weak-links formed at grain boundaries can be eliminated by the suggested materials' synthesis. [ABSTRACT FROM AUTHOR]

Topological semimetals, possessing topologically non-trivial band structures, serve as excellent platforms for realizing topological superconductivity through hard point-contact experiments. In this study, we successfully induce superconductivity in the three-dimensional Dirac semimetal, cubic PtBi2, using ferromagnetic and paramagnetic tips in hard point contact experiments. The induced superconductivity is proven to be insensitive to ferromagnetism and exhibits unconventional features in the point-contact spectra. The highest superconducting transition temperature ( T c ) reaches approximately 5.1 K, and the T c values are proven to have a positive correlation with the coupling between the tip and the sample. Furthermore, we extend our point-contact experiments to trigonal PtBi2, a material possessing a type-I Weyl semimetal band structure and triply degenerate points proximate to the Fermi level. Utilizing both ferromagnetic Ni tips and paramagnetic Ag tips, we successfully enhance superconductivity with a T c of up to 3.0 K in this material. The findings from point-contact measurements reveal that the enhanced superconductivity is compatible with ferromagnetism and the magnetism of the tip can affect the symmetry of the enhanced superconducting state. Given that the lattice structure remains stable under pressure up to 51.2 GPa for cubic PtBi2 and 12.9 GPa for trigonal PtBi2, the emergent superconducting states observed in these two PtBi2 materials could inherit their topological nontrivial nature and be promising candidates for topological superconductor. [ABSTRACT FROM AUTHOR]

In this study, we present the fabrication of large single-domain ternary (Sm,Eu,Gd)Ba 2 Cu 3 O 7-y bulk superconductor with enhanced superconducting properties using various REBa 2 Cu 3 O y (RE-123) as a liquid source via the top-seeded infiltration growth process (TSIG) in air. We employed a 1:1 ratio of REBa 2 Cu 3 O y (RE = Sm, Gd, Y and Er) and Ba 3 Cu 5 O 8 as a liquid source for fabrication. Impressively, all the obtained bulk samples exhibited a superconducting transition temperature T (c, onset) above 94 K. However, the bulk sample fabricated using Y-123 + Ba 3 Cu 5 O 8 as a liquid source demonstrated a T (c, onset) of 94.53 K, with a 40.14 % improvement in transition width (Δ T c) and at 77 K the bulk recorded a self-field critical current density (J c) value of 44.73 kA/cm2 & 10.62 kA/cm2 at 1T resulting in a remarkable 93.08 % improvement in self-field J c compared to the bulk sample fabricated using Er-123 + Ba 3 Cu 5 O 8. Microstructural analysis using a scanning electron microscope revealed a significant reduction in the mean size of secondary (211) phase particles, a significant reduction of 38.41 % is observed for the Y-123 + Ba 3 Cu 5 O 8 employed sample. [ABSTRACT FROM AUTHOR]

We present a theory for charge-4e superconductivity as a leading low-temperature instability with a nontrivial d-wave symmetry. We show that in several microscopic models for the pair-density-wave (PDW) state, when the PDW wave vectors connect special parts of the Fermi surface, the predominant interaction is in the bosonic pairing channel mediated by exchanging low-energy fermions. This bosonic pairing interaction is repulsive in the s-wave channel but attractive in the d-wave one, leading to a d-wave charge-4e superconductor. By analyzing the Ginzburg-Landau free energy including higher-order fluctuation effects of PDW, we find that the charge-4e superconductivity emerges as a vestigial order of PDW, and sets in via a first-order transition. Both the gap amplitude and the transition temperature decay monotonically with increasing superfluid stiffness of the PDW order. Our work provides a microscopic mechanism of higher-charge condensates with unconventional ordering symmetry in strongly-correlated materials. [ABSTRACT FROM AUTHOR]

FeSe0.4Te0.6 polycrystal bulks were synthesized using the solid‐state sintering method. We developed a novel multistep sintering process and studied the impact of the sintering cycle number. Different cycles of multistep sintering, ranging from one to four cycles were systematically arranged. It was found that the superconducting properties of the FeSe0.4Te0.6 polycrystal bulk using three cycles of sintering surpassed those of other samples, reaching a maximum of Tczero$T_{\mathrm{c}}^{{\mathrm{\ zero}}}$ = 13.4 K, Tconset$T_{\mathrm{c}}^{{\mathrm{\ onset}}}$ = 14.7 K, and a minimum of ∆Tc${T}_{\mathrm{c}}$ = 1.3 K. And the superconducting current density at 4 K reached 1.77 × 104 A/cm2, exhibiting a weak fishtail effect. At 9 K, a composite pinning effect emerged, consisting of normal point pinning and ∆κ surface pinning. The enhancement in superconductivity is attributed to improve uniformity in grain arrangement and more effective element diffusion. After multiple sintering cycles, the stacked grains exhibited increased thickness and the grain arrangement became dense. [ABSTRACT FROM AUTHOR]

MgB 2 superconductor bulks were fabricated using Mg and B precursors. The physical state of Mg (solid, liquid, or gas) significantly influences the final product, MgB 2 bulk. In this study, the Solid-Solid, Liquid-Solid, and Gas-Solid methods were employed to fabricate MgB 2 bulks. The superconducting properties and microstructure of various samples were systematically investigated. Notably, for the first time, nano-CT was utilized to comprehensively and non-destructively analyze the microstructure of MgB 2 bulks, particularly the size and distribution of voids, which serve as the primary barrier affecting the superconducting properties. By examining the microstructure characteristics, the infiltration effect of Mg in different physical states during the reaction was analyzed, and a feasible reaction model was established. This research contributes to a better understanding of the reaction mechanism of MgB 2 , which may aid other researchers in enhancing the properties of MgB 2 superconductors. [ABSTRACT FROM AUTHOR]

YBCO openwork structures were 3D-printed as cuboids with 4.5 × 4.5 × 2 mm dimensions and various filling degrees. Initial pycnometric data showed a slight variation in specimen densities (∼6.153 g/cm3), proving the production process uniformity. The consistency of YBCO superconducting phase (Y-123) was confirmed by Raman spectroscopy, X-ray diffraction and X-ray absorption spectroscopy. Microstructural and chemical homogeneity was proven by scanning electron microscopy with microprobe analysis. Transport (electrical and thermal) measurements accompanied by simulations of magnetic flux density at the produced structures revealed that they are heavily dependent of filling ratio and geometry. Additionally, this work proves that the 3D printing is an excellent method of fabricating high-quality superconducting structures of desired shapes accordingly to applicational demands. [ABSTRACT FROM AUTHOR]

Inspired by recent remarkable sets of experiments on UTe 2 : discoveries of the fourth horizontal internal transition line running toward a tetra-critical point (TCP) at H = 15 T, the off-axis high-field phases, and abnormally large Knight shift (KS) drop below T c for H ‖ a -magnetic easy axis, we advance further our theoretical work on the field (H)-temperature (T) phase diagram for H ‖ b -magnetic hard axis which contains a positive sloped H c2 departing from TCP. A nonunitary spin-triplet pairing with three components explains these experimental facts simultaneously and consistently by assuming that the underlying normal electron system with a narrow bandwidth characteristic to the Kondo temperature ∼ 30 K unsurprisingly breaks the particle-hole symmetry. This causes a special invariant term in Ginzburg–Landau (GL) free energy functional which couples directly with the 5f magnetic system, giving rise to the T c splitting and ultimately to the positive sloped H c2 and the horizontal internal transition line connected to TCP. The large KS drop can be understood in terms of this GL invariance whose coefficient is negative and leads to a diamagnetic response where the Cooper pair spin is antiparallel to the applied field direction. The present scenario also accounts for the observed d-vector rotation phenomena and off-axis phase diagrams with extremely high H c2 ≳ 70 T found at angles in between the b- and c-axes and between the bc-plane and a-axis, making UTe 2 a fertile playground for a possible topological superconductor. [ABSTRACT FROM AUTHOR]

The chiral 2 × 2 charge order has been reported and confirmed in the kagome superconductor RbV3Sb5, while its interplay with superconductivity remains elusive owing to its lowest superconducting transition temperature T C of about 0.85 K in the AV3Sb5 family (A = K, Rb, Cs) that severely challenges electronic spectroscopic probes. Here, utilizing dilution-refrigerator-based scanning tunneling microscopy down to 30 mK, we observe chiral 2 × 2 pair density waves with residual Fermi arcs in RbV3Sb5. We find a superconducting gap of 150 μeV with substantial residual in-gap states. The spatial distribution of this gap exhibits chiral 2 × 2 modulations, signaling a chiral pair density wave (PDW). Our quasi-particle interference imaging of the zero-energy residual states further reveals arc-like patterns. We discuss the relation of the gap modulations with the residual Fermi arcs under the space-momentum correspondence between PDW and Bogoliubov Fermi states. [ABSTRACT FROM AUTHOR]

The chiral 2 × 2 charge order has been reported and confirmed in the kagome superconductor RbV3Sb5, while its interplay with superconductivity remains elusive owing to its lowest superconducting transition temperature T C of about 0.85 K in the AV3Sb5 family (A = K, Rb, Cs) that severely challenges electronic spectroscopic probes. Here, utilizing dilution-refrigerator-based scanning tunneling microscopy down to 30 mK, we observe chiral 2 × 2 pair density waves with residual Fermi arcs in RbV3Sb5. We find a superconducting gap of 150 μeV with substantial residual in-gap states. The spatial distribution of this gap exhibits chiral 2 × 2 modulations, signaling a chiral pair density wave (PDW). Our quasi-particle interference imaging of the zero-energy residual states further reveals arc-like patterns. We discuss the relation of the gap modulations with the residual Fermi arcs under the space-momentum correspondence between PDW and Bogoliubov Fermi states. [ABSTRACT FROM AUTHOR]

This study investigates the vertex corrections of the optical conductivity in high-Tc superconductors for hole-spin wave scattering in the superconducting state. The Feynman diagram technique is used to determine the mathematical expressions of the ladder diagrams in the calculation of the current–current correlation function. The sum of these vertex terms leads to a self-consistent form of the vertex function. By evaluating the frequency summation through contour integration, a general expression for the current–current correlation function is obtained, which allows us to determine the zeroth-order term and the first-order correction of the optical conductivity explicitly. Our findings for the dc conductivity in a clean superconductor indicate that the zeroth-order term is zero, a result attributed to the conservation of momentum and energy. Meanwhile, the first-vertex correction reveals the Drude behavior in the superconducting state at zero frequency. [ABSTRACT FROM AUTHOR]

We provide a thermodynamic derivation of the only-phase Popov action functional, which is often adopted to study the low-energy effective hydrodynamics of a generic nonrelativistic superfluid. It is shown that the crucial assumption is the use of the saddle point approximation after neglecting the quantum-pressure term. As an application, we analyze charged superfluids (superconductors) coupled to the electromagnetic field at zero temperature. Our only-phase and minimally-coupled theory predicts the decay of the electrostatic field inside a superconductor with a characteristic length much smaller than the London penetration depth of the static magnetic field. This result is confirmed also by a relativistic only-phase Popov action we obtain from the Klein–Gordon Lagrangian. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the fractal nature of the local fractional Landau–Ginzburg–Higgs Equation (LFLGHE) describing nonlinear waves with weak scattering in a fractal medium. The main goal of the paper is to introduce and apply the Local Fractional Elzaki Variational Iteration Method (LFEVIM) for solution of LFLGHE. Convergence analysis of LFEVIM solution for general nonlinear local fractional partial differential equation is also provided. Two examples of the local fractional LFLGHE are considered to demonstrate the applicability of the proposed technique with numerical simulations on Cantor set. [ABSTRACT FROM AUTHOR]