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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)

Superconducting nanowire single photon detector (SNSPD) is a leading candidate for applications requiring the fundamental limit of light detection at high detection rates. While SNSPD technology employing nanowires from conventional low temperature superconducting detectors is mature with several commercial solutions, other material options with higher transition temperature approaching liquid nitrogen with faster signal responses are actively being explored. In this context, we develop a comprehensive model that predicts the final potential response from an SNSPD incorporating several physical and material aspects. A phase diagram of photon detection is developed that describes the latching phases and the photon sensitivity as a function of biasing current and temperature for both low temperature and high temperature superconductors. On the one hand, while low temperature superconductors are observed to be more sensitive than high temperature superconductors (HTSs) under any given biasing condition, a biasing window for a single photon detection with HTS nanowires is identified. On the other hand, HTS nanowires demonstrate three orders of magnitude faster response times than the low temperature superconductor nanowire at the same biasing condition, making it uniquely suited for several practical applications. [ABSTRACT FROM AUTHOR]

Motivated by searching room-temperature superconductors that could be realized near ambient conditions, palladium hydrides were chosen as the research subject considering that they can stably exist under ambient conditions, and Li as an electron donor for its outstanding performance in chemically tuning stability. A novel cubic phase structure of Li2PdH6 with a remarkably high estimated Tc of ∼165 K at 90 GPa was found using particle swarm optimization algorithm calculations. The superconducting behavior persists down to 10 GPa with a high Tc of 106.382 K. Even though the parent binary Pd–H system is not a good superconductor, the introduction of extra electrons breaks up the H2 molecules, inducing the increase of atomic hydrogen compared with parent hydride, which is necessary for outstanding superconducting behavior. The existence of relatively soft phonons associated with the H atoms in phonon dispersion curves is responsible for its high-Tc. Our results indicated that the doping of Li to binary hydrides, especially to binary hydrides with low-Tc that exist under ambient pressure, can produce robust phonon-mediated superconductivity. This may be a strategy to design and optimize room-temperature superconductors that can be synthesized under modest pressure. The findings may pave the way for realizing new high-Tc superconductors in experiments under lower pressure than recently documented superconducting hydrides. [ABSTRACT FROM AUTHOR]

The phenomenon of Berezinskii–Kosterlitz–Thouless (BKT) phase fluctuations and the superconducting fluctuations is investigated in a 40 nm thick granular aluminum film using magneto-transport measurements. The transport measurements suggest the possibility of strong electron–phonon (el–ph) interactions in contrast to a Bardeen–Cooper–Schrieffer superconductor. It shows a BKT transition of 2.304 K and a superconducting mean-field transition at 2.32 K. The presence of the resistive tail even before the BKT transition reflects the abundance of thermally activated free vortices. By analyzing the excess conductivity, Gaussian–Ginzburg–Landau superconducting fluctuations are observed above the superconducting transition, which causes rounding of the transition region even before the superconducting transition. The temperature dependence of the fluctuation conductivity in zero magnetic field exhibits distinct signatures of the two-dimensional direct Aslamazov–Larkin theory, with a significant contribution from the Maki–Thompson (MT) model. Furthermore, the anomalous behavior of the fluctuation conductivity at higher temperatures and perpendicular magnetic fields (up to 700 mT) is explained in terms of the total-energy cutoff (=0.72) in the low-wavelength region of the superconducting fluctuations and a pair-breaking parameter (∼0.031). Further studies on the pair-breaking parameter indicate the presence of the el–ph scattering, which diminishes the MT contribution. Our study carries important bearings on how the BKT phase fluctuations and superconducting amplitude fluctuations control the conductivity of granular superconductor near and above the transition region as non-equilibrium properties of weakly disordered granular superconductors. This research is of significance, offering insights into the fundamental properties of granular superconductivity and aiding in the comprehension of nano-structured thin film devices. [ABSTRACT FROM AUTHOR]

The recent discovery of MoB2 with a superconducting transition temperature (Tc) of up to 32 K at 100 GPa provides new insights into the metallization and subsequently high-Tc superconductivity of diborides, highlighting the potential of transition metals in these compounds. We herein re-evaluated the structure, mechanical, and superconducting properties of IrB4 under pressure up to 300 GPa using first-principles. Our calculations reveal that a new P21/c phase exhibiting a hardness of 15.75 GPa surpasses the stability of the C2/m structure identified through the particle swarm optimization at ambient pressure. Upon compressing, the P21/c phase transforms into an MgB2-type structure with a space group of P63/mmc at 62.5 GPa and then into the orthorhombic Cmca phase above 109 GPa. Unlike semiconductor behavior of the atmospheric pressure phase, the two high-pressure structures are metallic and superconducting, with Tc values of 29.90 for P63/mmc at 62.5 GPa and 13.45 K for Cmca at 125 GPa. Analysis of the electronic structure and electron–phonon coupling (EPC) reveals that the high Tc, similar to MgB2-type MoB2, stems from the Van Hove Singularities (VHS) near the Fermi level donated by transition metal Ir. The effect further enhances the EPC based on the boron contribution. More interestingly, pressure has little impacts on the position of the VHS. These findings provide a new platform for designing advanced high-Tc superconductors. [ABSTRACT FROM AUTHOR]

The recent discovery of MoB2 with a superconducting transition temperature (Tc) of up to 32 K at 100 GPa provides new insights into the metallization and subsequently high-Tc superconductivity of diborides, highlighting the potential of transition metals in these compounds. We herein re-evaluated the structure, mechanical, and superconducting properties of IrB4 under pressure up to 300 GPa using first-principles. Our calculations reveal that a new P21/c phase exhibiting a hardness of 15.75 GPa surpasses the stability of the C2/m structure identified through the particle swarm optimization at ambient pressure. Upon compressing, the P21/c phase transforms into an MgB2-type structure with a space group of P63/mmc at 62.5 GPa and then into the orthorhombic Cmca phase above 109 GPa. Unlike semiconductor behavior of the atmospheric pressure phase, the two high-pressure structures are metallic and superconducting, with Tc values of 29.90 for P63/mmc at 62.5 GPa and 13.45 K for Cmca at 125 GPa. Analysis of the electronic structure and electron–phonon coupling (EPC) reveals that the high Tc, similar to MgB2-type MoB2, stems from the Van Hove Singularities (VHS) near the Fermi level donated by transition metal Ir. The effect further enhances the EPC based on the boron contribution. More interestingly, pressure has little impacts on the position of the VHS. These findings provide a new platform for designing advanced high-Tc superconductors. [ABSTRACT FROM AUTHOR]

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 successfully synthesized tetragonal FeS with various Fe:S molar ratios using a hydrothermal method, and the EDS and XRF results confirmed that FeS exhibits superconductivity within the Fe and S element ratio range of 1.155–1.274, rather than a strict stoichiometric ratio. The reaction temperature can not only play a crucial role in determining the purity of the obtained FeS phase but also significantly alter its micromorphology. Significantly, by analyzing the relationship between the Fe:S actual molar ratio and Tc as well as the Fe:S actual molar ratio and unit cell volume, FeS exhibits dome-shaped superconductivity and shows a negative correlation with Tc and chemical pressure. Furthermore, considering the correlation between anion height (hanion) and Tc, Tc reaches the maximum value of 4.53 K for hanion ≈ 1.28 Å, a behavior distinct from that of observed in Fe-pnictide superconductors. In short, our experimental results provide a unique perspective to deepen our understanding of FeS superconductors. [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]

The current pressing challenge in the field of superconducting hydride research is to lower the stable pressure of such materials for practical applications. Molecular hydrides are usually stable under moderate pressure, but the underlying metallization mechanism remains elusive. Here, the important role of chemical interactions in governing the structures and properties of molecular hydrides is demonstrated. A new mechanism is proposed for obtaining high‐temperature and even room‐temperature superconductivity in molecular hydrides and report that the ternary hydride NaKH12 hosts Tc values up to 245 K at moderate pressure of 60 GPa. Both the excellent stability and superconductivity of NaKH12 originate from the fact that the localized electrons in the interstitial region of the metal lattice occupying the crystal orbitals well matched with the hydrogen lattice and forming chemical templates to assist the assembly of H2 units. These localized electrons weaken the H─H covalent bonds and improve the charge connectivity between the H2 units, ensuring the strong coupling between electrons and hydrogen‐dominated optical phonons. The theory provides a key perspective for understanding the superconductivity of molecular hydrides with various structural motifs, opening the door to obtaining high‐temperature superconductors from molecular hydrides at moderate pressures. [ABSTRACT FROM AUTHOR]

A personal perspective is given on a decade of research on Majorana bound states (MBS) in hybrid devices of semiconducting nanowires covered with a superconductor. Predicted experimental signatures like zero-bias anomalies turned out to be false positive evidence for topological MBS. Zero-bias conductance peaks have found alternative explanations in terms of material disorder and smooth boundary potentials. A recount is given on various predictions, observations and re-interpretations, as well as the lessons learned in retrospect and an outlook on the future. [ABSTRACT FROM AUTHOR]

Background: Gold ormus is a type of superconductor that can exhibit superconductivity at temperatures below 1 Kelvin, allowing it to conduct electricity without resistance. While not as widely used as other materials like niobium or lead, gold ormus is valuable for research in superconductivity. Limited studies have been conducted on gold ormus. Numerical simulations of the Ginzburg–Landau theory have yielded important results for both gold ormus. Results: Class-I and class-II superconducting gold ormus, have been successfully simulated using the Runge–Kutta fourth-order method. Our analysis shows the convergence of our simulation outcomes and emphasizes the importance of considering truncation error and selecting appropriate step sizes for accurate results. The periodic factor of penetration (PFP) for each superconductor has been determined, with class-I superconducting gold ormus having a PFP of 250 nm, class-II superconducting gold ormus having a PFP of 566.2 nm. The relationship between the PFP and the length of the penetration depth has also been revealed. Conclusions: Our study confirms the accuracy of the Runge–Kutta fourth-order method in simulating superconductors. By analyzing the PFP for different superconducting materials, we have identified trends in penetration depth that contribute to understanding superconductivity. Our simulations provide valuable insights for further research in the field of superconductivity. Adjusting parameters carefully ensures reliable simulations and advances progress in superconductivity research. [ABSTRACT FROM AUTHOR]

The increasing financial and environmental cost of many inorganic materials has motivated study into organic and "green" alternatives. However, most organic compounds contain a large number of atoms in the primitive unit cell, posing a significant barrier to high-throughput screening for functional properties. In this work, we attempt to overcome this challenge and identify superconducting candidates among the metal-organic-frameworks in the organic materials database using a recently proposed proxy for the electron-phonon coupling. We then isolate the most promising candidate for in-depth analysis, C9H8Mn2O11, providing evidence for superconductivity below 100mK. [ABSTRACT FROM AUTHOR]

Superconducting niobium serves as a key enabling material for superconducting radio frequency (SRF) technology as well as quantum computing devices. Niobium has a high propensity for the uptake of hydrogen. At room temperature, hydrogen commonly occupies tetragonal sites in the Nb lattice as the metal (M)–gas (H) phase. When the temperature is decreased, however, a solid solution of Nb-H begins to precipitate. In this study, we show the first identified topographical features associated with nanometer-size hydride phase (Nb1−xHx) precipitates on the surface of the metallic superconducting niobium using cryogenic-atomic force microscopy (AFM). Further, high energy grazing incidence X-ray diffraction reveals information regarding the structure and stoichiometry of these precipitates. Finally, through time-of-flight secondary ion mass spectroscopy (ToF-SIMS), we locate atomic hydrogen sources near the top surface. This systematic study clarifies nanometer scale hydrides precipitated on the surface of the SRF Nb cavity that exhibit performance degradation at a high accelerating field regime. [ABSTRACT FROM AUTHOR]

Abrikosov vortices play a fundamental role in the magnetic and electric properties of superconductors. The study of their pinning forces is essential to better understand the stability of vortex lattices, with the aim of increasing critical currents in superconductors. However, the study of vortices is challenging because of their nanometric sizes and the large variation in the pinning forces. In this Letter, we use a single nitrogen-vacancy center in a nanodiamond as a nanoscale magneto sensor to locally probe single vortices and their pinning effects in a thin niobium film. This simple, far-field optical approach also offers the possibility of manipulating a single spin with a single flux quantum. [ABSTRACT FROM AUTHOR]

Charge stripes have been widely observed in many different types of unconventional superconductors, holding varying periods (P ) and intensities. However, a general understanding on the interplay between charge stripes and superconducting properties is still incomplete. Here, using large-scale unbiased numerical simulations on a general inhomogeneous Hubbard model, we discover that the charge-stripe period P , which is variable in different real material systems, could dictate the pairing symmetries—d wave for P ≥ 4 , s and d waves for P ≤ 3 . In the latter, tuning hole doping and charge-stripe amplitude can trigger a d-s wave transition and magnetic-correlation shift, where the d-wave state converts to a pairing-density wave state, competing with the s wave. These interesting phenomena arise from an unusual stripe-induced selection rule of pairing symmetries around on-stripe region and within inter-stripe region, giving rise to a critical point of P = 3 for the phase transition. In general, our findings offer important insights into the differences in the superconducting pairing mechanisms across many P -dependent superconducting systems, highlighting the decisive role of charge stripe. Charge stripes have been observed in various unconventional superconductors, but their interplay with the superconducting properties is not fully understood. Here, the authors show, via large-scale numerical simulations based on an inhomogeneous Hubbard model, that the charge stripe period can dictate the superconducting pairing symmetry. [ABSTRACT FROM AUTHOR]

Kagome lattices have garnered significant interest over the decades due to their rich physics and implications for exotic superconductors and topological materials. In particular, the so‐called "breathing Kagome lattice" (BKL) is often used as a prototypical model to understand higher‐order topological insulators. Here it is demonstrated that higher‐order corner states exist in a specially distorted Kagome lattice, resembling the "Inverse Hexagram" lattice distortion originally introduced in the study of charge density waves in Kagome metals. Importantly, it is found that such an Inverse Hexagram‐like Kagome lattice with C6 rotational symmetry hosts two types of in‐gap corner states, in contrast to a flat‐cutting BKL of C3 symmetry that supports only one type of corner state under the tight‐binding condition. It is shown that the nontrivial corner states exhibit a fractional corner anomaly, revealing the feature of higher‐order topology. Using laser‐written waveguide lattices as a photonic platform, these two types of corner states are experimentally observed, along with a direct comparison with the corner excitation at their trivial counterparts. Experimental observations are further corroborated by numerical simulations and stability analysis under random perturbation. These results may prove relevant and applicable to similar phenomena in other Kagome platforms beyond photonics. [ABSTRACT FROM AUTHOR]

We present a MgB2-based Microwave Kinetic Inductance Detector (MKID) featuring a quality factor Qi ~ 105 and noise equivalent power NEP ~ 10−14  W / Hz at 2 K. In comparison to YBCO-based MKIDs, the MgB2 detector shows greater sensitivity to both temperature and magnetic field, a result of its two-gap nature and relatively low critical H c 2 field. Our data indicate that MgB2 is more advantageous for MKID applications at temperatures lower than 3 K. [ABSTRACT FROM AUTHOR]

Iron-based superconductors have strong potential for magnet applications through their very high upper critical field, low anisotropy and manufacturability through the powder-in-tube (PIT) route. The engineering critical current density (Je) is a key parameter for measuring the maximum current density that superconducting materials can withstand in practical applications. It serves as a bridge between theoretical research and practical applications of superconductors and has great significance in promoting the development and application of superconducting technology. In this study, Ag sheathed Ba0.6K0.4Fe2As2 (Ba-122) iron-based superconducting tapes were prepared by using the process of drawing, flat rolling and heat treatment by hot pressing (HP). For the first time, the filling factor of the tapes increased to about 40%, leading to a reduction in the volume fraction of Ag, consequently lowering the overall cost. The optimal parameters for achieving high transport Je were obtained by comparing the effects of different HP pressures on the properties and micro-morphology of the tapes. The prepared mono-filament tapes are capable of carrying the transport Je of 4.1 × 104 A/cm2 (Ic = 350 A) at 4.2 K, 10 T, marking the highest Je reported for Ba-122 wires and tapes to date. Our results show that high transport Je can be obtained in Ba-122 superconducting tapes, and iron-based superconductors have a promising future in practical applications. [ABSTRACT FROM AUTHOR]

We present a method of creating high-density superconducting flexible wiring on flexible thin silicon substrates. The flexible wiring, called SOI flex, is created by depositing superconducting wiring on a silicon-on-insulator (SOI) wafer, selectively etching away the thicker silicon section handle layer, and bending the thinner silicon device layer. We show measurements of superconducting transition temperature and critical current for Mo, Nb, and Al on SOI flex. We discuss the expected advantages of SOI flex for low-temperature detector applications, as well as the role of stress and strain in bent silicon and niobium. [ABSTRACT FROM AUTHOR]

Among the REBa2Cu3O7‐δ (REBCO or RE123, RE = rare earth element) family, SmBCO is preferably used in top‐seeded melt‐growth (TSMG) because of its outstanding property and more controllable stoichiometry 123. Nevertheless, the refinement of Sm2BaCuO5 (Sm211) particles has been challenging for high‐performance SmBCO bulks. Conventional precursor powders (SmBa2Cu3O7‐δ plus Sm2BaCuO5) intrinsically result in enlarging Sm2BaCuO5 particles due to their coarsening and epitaxial growth during the heating process. Here, we used modified precursor powders (MPPs, Sm2O3 plus Ba2Cu3O5) in air‐processed TSMG, in which there is neither Sm211 in the beginning nor related enlargement during heating. Consequently, the nucleation catastrophe of Sm211 occurred above the peritectic temperature, which in situ formed, possessing naturally small size. Further, aiming to suppress the Sm/Ba substitution, Ba‐rich MPP, substituting Ba2Cu3O5 with Ba3Cu4O7) was employed, producing an excellent SmBCO bulk with a diameter of 24 mm: levitation force of 51.5 N and trapped field of 0.537 T. Optical micrographs and quantitative analyses confirmed the superior refinement and distribution of Sm211 particles in SmBCO bulks. Most importantly, new strategies in this work are widely applicable for developing cost‐effective and high‐performance other REBCO bulk superconductors. [ABSTRACT FROM AUTHOR]

This study explores the impact of small air gaps in high-temperature superconducting cables on the insulating material polypropylene-laminated paper (PPLP), and the aging rules and mechanisms of the insulating material during practical uses. An air gap discharge test platform was built to simulate air gap fault defects of superconducting cables in the real operating environment. Hierarchical clustering method was used to divide the gap discharge process of defect model into four stages. Insulation damage assessment was conducted on the intermediate layer PP of the superconducting insulation material PPLP at different discharge stages, revealing surface changes and periodic alterations in dielectric properties. The morphological features, roughness, infrared spectra, dielectric loss, surface resistivity, and other phase characteristics of the superconducting insulation layer material were analyzed at different stages of air gap defects. Molecular group cracking in PP was attributed to the bond breakage on the main chain. These findings provide insights into high-temperature superconducting cable insulation under air gap discharge and provide a guideline for practical applications in semi-conductive industries. [ABSTRACT FROM AUTHOR]