Showing papers on "High-temperature superconductivity published in 2023"

Conceptual Design of 20 T Hybrid Accelerator Dipole Magnets

Abstract: Hybrid magnets are currently under consideration as an economically viable option towards 20 T dipole magnets for next generation of particle accelerators. In these magnets, High Temperature Superconducting (HTS) materials are used in the high field part of the coil with so-called “insert coils”, and Low Temperature Superconductors (LTS) like Nb ₃ Sn and Nb-Ti superconductors are used in the lower field region with so-called “outsert coils”. The attractiveness of the hybrid option lays on the fact that, on the one hand, the 20 T field level is beyond the Nb ₃ Sn practical limits of 15-16 T for accelerator magnets and can be achieved only via HTS materials; on the other hand, the high cost of HTS superconductors compared to LTS superconductors makes it advantageous exploring a hybrid approach, where the HTS portion of the coil is minimized. We present in this paper an overview of different design options aimed at generating 20 T field in a 50 mm clear aperture. The coil layouts investigated include the Cos-theta design (CT), with its variations to reduce the conductor peak stress, namely the Canted Cos-theta design (CCT) and the Stress Management Cos-theta design (SMCT), and, in addition, the Block-type design (BL) including a form of stress management and the Common-Coil design (CC). Results from a magnetic and mechanical analysis are discussed, with particular focus on the comparison between the different options regarding quantity of superconducting material, field quality, conductor peak stress, and quench protection.

Magnetic flux trapping in hydrogen-rich high-temperature superconductors

Abstract: Abstract Recent discoveries of superconductivity in various hydrides at high pressures have shown that a critical temperature of superconductivity can reach near-room-temperature values. However, experimental studies are limited by high-pressure conditions, and electrical transport measurements have been the primary technique for detecting superconductivity in hydrides. Here we implement a non-conventional protocol for the magnetic measurements of superconductors in a SQUID magnetometer and probe the trapped magnetic flux in two near-room-temperature superconductors H 3 S and LaH 10 at high pressures. Contrary to traditional magnetic susceptibility measurements, the magnetic response from the trapped flux is almost unaffected by the background signal of the diamond anvil cell due to the absence of external magnetic fields. The behaviour of the trapped flux generated under zero-field-cooled and field-cooled conditions proves the existence of superconductivity in these materials. We reveal that the absence of a pronounced Meissner effect is associated with the very strong pinning of vortices inside the samples. This approach can also be a tool for studying multiphase samples or samples that have a low superconducting fraction at ambient pressure.

Experimental study of a high-temperature superconducting induction/synchronous motor with REBCO bulk bars for transportation applications

Abstract: Lightweight and highly efficient high-temperature superconducting (HTS) rotating electric machines show great potential for transportation applications. An advantage of RE-Ba-Cu-O (REBCO, where RE=rare earth) bulk superconductors over stacked HTS tapes is their ability to carry larger and more homogenous currents. This study is the first in which an HTS induction/synchronous motor (HTS-ISM) with Gd-Ba-Cu-O (GdBCO) bulk superconductors has been successfully designed, fabricated, and tested. Our fabricated prototype featured a squirrel-cage rotor wound with 44 GdBCO bulk bars that were embedded in the rotor iron and connected at both ends using Y-Ba-Cu-O (YBCO) tapes to form a short circuit. First, the critical current of the bulk sample was investigated under a magnetic field perpendicular to its top surface at 77 K. Subsequently, no-load and load tests were performed in liquid nitrogen at different frequencies to verify the performance of the prototype. Finally, we thoroughly analyzed the differences between the proposed HTS-ISM that utilizes GdBCO bulk bars and developed HTS-ISMs that utilize a few turns of YBCO or Bi-Sr-Ca-Cu-O (BSCCO) tapes per bar.

Thermal decoupling in high-$T_c$ cuprate superconductors

Abstract: Although many years have passed since the discovery of high-critical-temperature (high-$T_c$) superconducting materials, the underlying mechanism is still unknown. The B1g phonon anomaly in high-Tc cuprate superconductors has long been studied; however, the correlation between the B1g phonon anomaly and superconductivity has yet to be clarified. In the present study, we successfully reproduced the B1g phonon anomaly in YBa$_2$Cu$_3$O$_7$ (YBCO) using an ab initio molecular dynamics (AIMD) simulation and temperature-dependent effective potential (TDEP) method. The Ag phonon by Ba atoms shows a more severe anomaly than the B1g phonon at low temperatures. Our analysis of the phonon anomaly and the temperature-dependent phonon dispersion indicated that decoupling between thermal phenomena and electron transport at low temperatures leads to layer-by-layer thermal decoupling in YBCO. Electronically and thermally isolated Ba atoms in YBCO are responsible for the thermal decoupling. The analytic study of the thermal dcoupling revealed that Planckian dissipation expressing linear-T resistivity is another expression of the Fermi liquid of the CuO$_2$ plane. The Uemura plot of the relationship between Tc and the Fermi temperature, as well as the superconducting dome in YBCO, is explained rigorously and quantitatively. Our findings not only present a new paradigm for understanding high-Tc superconductivity but also imply that the spontaneous formation of low-temperature layers in materials can lead to revolutionary changes in the thermal issues of industrial fields.

Terahertz Radiations and Switching Phenomena of Intrinsic Josephson Junctions in High-Temperature Superconductors: Josephson Phase Dynamics in Long- and Short-Ranged Interactions

Abstract: Studies on intrinsic Josephson junctions (IJJs) of cuprate superconductors are reviewed. A system consisting of a few IJJs provides phenomena to test the Josephson phase dynamics and its interaction between adjacent IJJs within a nanometer scale, which is unique to cuprate superconductors. Quasiparticle density of states, which provides direct information on the Cooper-pair formation, is also revealed in the system. In contrast, Josephson plasma emission, which is an electromagnetic wave radiation in the sub-terahertz frequency range from an IJJ stack, arises from the synchronous phase dynamics of hundreds of IJJs coupled globally. This review summarizes a wide range of physical phenomena in IJJ systems having capacitive and inductive couplings with different nanometer and micrometer length scales, respectively.

Thermal Influence of a Variable Temperature Insert on The High-Temperature Superconductor Coils of a Conduction Cooled High Magnetic Field Generator

Abstract: This paper presents the numerical modeling results of the temperature for a YBCO-type high-temperature superconducting (HTS) winding of an electromagnet that generates a magnetic field with a maximum magnetic flux density of 5 T. The electromagnet is made in a Helmholtz configuration, with circular double pancake-type coils. Inside the central area of the electromagnet is placed a measuring cell with the sample exposed to the magnetic field, which has a variable temperature in the range of 4.2 to 300 K. The change in the temperature of the HTS winding due to the radiative thermal heat absorbed from the cell, is studied as a function of the temperature of the measuring cell, which can vary between 4.2 K and 300 K. The modeling results shows a maximum value of 0.334 W which give rise of the temperature of the HTS coils to 5 K.

Evaluation of the Interface Resistance on Heated REBCO Tape

Abstract: Soldering is one of the most common jointing methods in a tape-to-tape joint of Rare-earth Barium Copper Oxide (REBCO) tapes. In this procedure, heating REBCO tapes is inevitable. In soldered lap joints, it was reported that the joint resistance varies depending on the heating temperature and duration of the soldering process. The joint resistance is composed of several factors. One of the factors is the interface resistance between Cu/Ag and Ag/REBCO interfaces in the REBCO tape. In this study, we investigated how the interface resistance changes due to heating process of REBCO tapes. We prepared REBCO tapes heated at 300 °C for 1, 5, and 10 minutes and evaluated the critical current ( I _c ) with a four-terminal method as well as the interface resistance of the tapes with the contact-probing current transfer length method in a liquid nitrogen bath, self-field. Also, the temperature dependence of the interface resistivity of non-heated tape was evaluated from 10 K to critical temperature T _c . As a result, the interface resistivity (interface resistance for 1 cm ² joint area) increased from 12 nΩ⋅cm ² to 55 nΩ⋅cm ² at the most and there was a strong correlation between I _c degradation and the increase of the interface resistivity. The interface resistivity of non-heated tape decreased in the temperature range of 10 K to 85 K. However, it changed to increasing from 85 K to T _c .

Investigation of the microhardness of composite materials high-temperature superconductor YBCO—MoO3 nanofibers

Abstract: В работе исследованы сверхпроводящие поликристаллические композиты YBa2Cu3O7-x + MoO3 с содержанием нановолокон MoO3 1, 5, 10, 15% (мас.). Из измерений электрического сопротивления определены температура и ширина перехода в сверхпроводящее состояние образцов с описанием вероятных механизмов наблюдаемых изменений. Из измерений микротвердости по Виккерсу определены модуль упругости, предел текучести, вязкость разрушения и индекс хрупкости. При исследованиях физико-механических свойств объемных образцов ВТСП содержащих MoO3, для интерпретации данных микроиндентирования и объяснения результатов с учетом эффекта размера вдавливания было использовано пять различных моделей.

Catalogue of phonon modes in several cuprate high-temperature superconductors from density functional theory

Abstract: Cuprates are promising candidates for study in developing higher temperature superconductors. A thorough understanding of a material’s phonon modes enables further investigation of its emergent properties, however, no complete reference of the phonon modes exists. Here, using density functional theory, we evaluate the phonon frequencies and atomic displacements for La2CuO4, Bi2Sr2CuO6, and Bi2Sr2CaCu2O8, in their tetragonal structures. The phonon modes for all materials agree with those expected from space group symmetry and display instabilities corresponding to known low-temperature structural phase transitions.

Pulse Field Magnetization (PFM) With Sectioned HTS Stacked Tape Structures for Electrical Machine

Abstract: High temperature superconducting (HTS) stacks of superconducting tapes provide a solution for all-superconducting electrical machines since they could work as trapped-field magnets. Most experiments with these stacks use pieces of tapes with relatively small areas as wider tapes are more difficult to acquire, therefore in this paper we investigate substitutions for these wider tapes to be implemented in superconducting electrical machines. With different stack architectures and substrate materials made by SuperOx, AMSC and THEVA, the magnetizing effect using pulse field magnetization (PFM) would be different. To explore the differences of this effect, sectioned stacks are tested in a modified synchronous machine designed by ASuMED under liquid nitrogen conditions. By changing different sectioned stacks of tape and testing them under the same condition, the characteristics of the trapped flux, magnetization and demagnetization could be affected, different stacks are simulated with COMSOL finite element models using an electromagnetic-thermal coupled model, and different stacks are tested with different charging voltages.

Practical Forecasting of AC Losses in Multi-Layer 2G-HTS Cold Dielectric Conductors

Abstract: With the recent progresses on the designing and manufacturing of lightweight and high engineering current density superconducting cables, the need for an established, fast, and sufficiently accurate computational model for the forecasting of AC-losses in cold-dielectric conductors, is pivotal for increasing the investment confidence of power grid operators. However, validating such models is not an easy task, this because on the one hand, there is a low availability of experimental results for large scale power cables and, on the other hand, there is a large number of 2G-HTS tapes involved whose cross-sectional aspect ratio hinders the numerical convergence of the models within reasonable delivery times. Thus, aiming to overcome this challenge, we present a detailed two-dimensional H-model capable to reproduce the experimentally measured AC-losses of multi-layer power cables made of tens of 2G-HTS tapes. Two cable designs with very high critical currents have been considered, the first rated at 1.7 kA critical current, consisting of fifty 4 mm width 2G-HTS tapes, these split in 5 concentric layers wound over a cylindrical former, with the three inner layers forming an arrangement of 24 tapes shielded by two further layers with 13 tapes each. This cable is contrasted with a size wise equivalent cable with 67 superconducting tapes rated at 3.2 kA critical current, whose design implies the use of 40 tapes of 3 mm width split within four core layers, and 27 tapes of 4 mm width distributed in two shielding layers. In both situations a remarkable resemblance between the simulations and experiments has been found, rendering to acceptable estimates of the AC-losses for cold dielectric conductors, and offering a unique view of the local electrodynamics of the wound tapes where the mechanisms of shielding, magnetization, and transport currents can coexist within the hysteretic process.

Genetic algorithms molecular effect model optimization computational method for high temperature superconductors

Abstract: Genetic algorithms software was applied in 3D Graphical and Interior Optimization methods for two High Temperature Superconductors (HTSCs) classes. Namely, Tin (Sn) class with [TC > 0°] and Thallium (Tl) one subject to [TC ˂ 0°, TC > 0°] in Molecular Effect Model (MEM). Results comprise Tikhonov Regularization Functional mathematical algorithms for these HTSCs group without using logarithmic changes. Results also show the contrasts between these two classes for Molecular Effect Model (MEM) hypothesis. Solutions show a series of 2D/3D imaging process charts complemented with a group of numerical results. Electronics Physics applications for Superconductors and High Temperature Superconductors and Medical Technology are specified for MEM and presented.

Thermodynamically stable room-temperature superconductors in Li-Na hydrides under high pressures

Abstract: Room-temperature superconductivity has been a long-standing goal for scientific progress and human development. Thermodynamic stability is a prerequisite for material synthesis and application. Here, we perform a combination of high-throughput screening and structural search and uncover two thermodynamically stable room-temperature superconductors, Fd-3m-Li2NaH17 and Pm-3n-LiNa3H23, exhibiting extraordinary critical temperature of 340 K at 300 GPa and 310 K at 350 GPa, respectively. Li2NaH17 possesses the highest Tc among all the thermodynamically stable ternary hydrides hitherto found. The dominated H density of states at the Fermi level and the strong Fermi surface nesting are favorable for the emergence of room-temperature superconductivity. Their excellent superconducting properties help us understand the mechanism of room-temperature superconductivity and find new room-temperature superconductors. Interestingly, the structures of LiNa3H23 and Li2NaH17 equal to the identified type-I and II clathrate geometry. Our results provide a structural reference and theoretical guidance for later experimental structure determination and theoretical search for high temperature superconductors.

Automatic Modeling of High-Temperature Superconducting Cable Using Reinforcement Learning

Abstract: This paper proposes a technique of automatic modeling for high-temperature superconducting (HTS) cables. Reinforcement learning (RL), which is a representative methodology for automation and intelligence, is applied for the automation of the proposed modeling. To reflect the high-frequency characteristics of the HTS cables in the proposed modeling, reflectometry-based cable modeling is used. In addition, for agent training, an environment that combines simulation and experiment results is proposed, and detailed techniques for the process of the proposed RL model are introduced. The proposed technique is demonstrated by experiment using an actual HTS cable under 77 K and 300 K conditions. It is expected that the proposed technique will allow anyone without the related knowledge to perform the modeling of the HTS cables.

Systematic Design of Phonon-Engineered Superconductors: Optimizing Electron Pairing for High-Temperature Superconductivity

Abstract: Abstract High-temperature superconductivity (HTS), occurring above 77 K, promises significant advancements in energy-efficient technologies. Despite extensive research, a comprehensive understanding of HTS remains elusive, and discovering new materials or mechanisms has been largely serendipitous. This study presents a novel explanation for HTS, focusing on manipulating phonon-mediated electron pairing through enhancing electron-phonon coupling and optimizing phonon density of states (DOS). The proposed approach provides a systematic pathway for designing materials exhibiting HTS. Experimental results confirm successful realization of HTS in a new class of materials, termed "phonon-engineered superconductors" (PESCs), offering a promising platform for future research and technological advancements.

Aluminium-Stabilized High-Temperature Superconducting Cable for Particle Detector Magnets

Abstract: Within the context of EP R&D, CERN is developing a high-temperature superconducting (HTS) conductor for future superconducting detector magnet projects. The conductor features a Rare-Earth Barium Copper Oxide (REBCO) tapes soldered to a copper-coated high-purity aluminium stabilizer. Critical currents of the 200 mm long straight cable samples measured with various numbers of REBCO tapes at 77 K are consistent with empirical scaling formulas for critical current within 10%. A few percent deviations are expected to arise from the critical current variation along the length of the HTS tape. No degradation was observed after multiple soldering and de-soldering cycles at 165 $^\mathrm{o}$ C with Bi–Sn based solder and after thermal cycling between 77 K and room temperature. However, extreme bending (of 100 mm radius) of the already soldered HTS cable leads to failure of the cable. We repeated the critical current measurements with a 650 mm long cable loop sample with 85 mm bending radius, where the HTS tapes were soldered after the aluminium profile was bent. The critical current of the HTS cable loop was 7% lower than the prediction. Based on the first critical current measurements, the HTS cable preparation method presented in this work results in repeatable quality aluminium-stabilized HTS cable.

Magnetization Loss Measurement of Twisted Stacked Tape Cable and Comparison With CORC

Abstract: High Temperature Superconducting (HTS) cables for large current capacity are being studied in several forms for power device applications. Currently, the cables are being developed for DC applications rather than AC applications. However, if a technology for reducing AC loss is developed, it will be possible to apply HTS cables to various AC devices. Twisted Stacked-Tape Cable (TSTC) is one of the large current HTS cables. It is made by stacking and twisting multiple HTS tapes for large current capacity. The HTS tapes in TSTC should be twisted for the uniformity of current distribution in each tape. Since the HTS tape has a wide thin film shape, it is very difficult to twist itself. In this paper, we measured the magnetization losses of TSTC samples without the striations under AC magnetic fields that had peak values below 0.1 T. Several molds for the TSTC samples were made by using a 3D printer. TSTC samples had several numbers of stacked tapes and two kinds of the tape width. The magnetization losses of the samples in the molds were measured under uniform AC magnetic fields. The experimental results were compared to those of the straight HTS stacked cables and conductor on round core (CORC) cables.

The temperature dependent surface critical magnetic field (Hc3) of K0.73Fe1.68 Se2 superconductor by semi-anisotropic two band Ginzburg-Landau approach

Abstract: In this study, we used a two-band Ginzburg-Landau technique to investigate the surface critical magnetic field (Hc3 ) of magnetic superconductors, with the first band being an anisotropic superconductor and the second band being an isotropic superconductor. Following the calculation of the 1st Ginzburg-Landau equation, a surface critical magnetic field and its temperature dependent surface critical magnetic field were solved analytically using the variation method. Based on Changjan and Udomsamuthirun’s temperature dependency model, we discovered that fits best with experimental data of K0.73Fe1.68 Se2 superconductor, vicinity of the critical temperature.

Experimental study on quench protection method for HTS coil that uses Cu tape co-wound with HTS tape

Abstract: The authors previously proposed a quench protection method for a high-temperature superconducting (HTS) coil that uses Cu tape co-wound with HTS tape (Cu-CW method). In this method, when a quench occurs in the HTS coil, part of the current in the HTS coil is quickly transferred to the co-wound Cu tape coil by shorting the Cu coil with a resistor due to the tight magnetic coupling of both coils, and the hot-spot temperature of the HTS coil is reduced due to the quick reduction of the HTS coil current. The previous work showed by a numerical simulation that the method is effective to improve the quench protection performance compared with a commonly used detect and dump method (D&D method). In this work, the effectiveness of the method was studied by an experiment using small-scale test coils wound with yttrium barium copper oxide (YBCO) coated tapes to experimentally simulate quench behaviours of HTS coils of significant scale.

Discovering Chemically Novel, High-Temperature Superconductors

Abstract: One of the biggest unsolved problems in condensed matter physics is what mechanism causes high-temperature superconductivity and if there is a material that can exhibit superconductivity at both room temperature and atmospheric pressure. Among the many important properties of a superconductor, the critical temperature (Tc) or transition temperature is the point at which a material transitions into a superconductive state. In this implementation, machine learning is used to predict the critical temperatures of chemically unique compounds in an attempt to identify new chemically novel, high-temperature superconductors. The training data set (SuperCon) consists of known superconductors and their critical temperatures, and the testing data set (NOMAD) consists of around 700,000 novel chemical formulae. The chemical formulae in these data sets are first passed through a collection of rapid screening tools, SMACT, to check for chemical validity. Next, the DiSCoVeR algorithm is used to train on the SuperCon data to form a model, and then screens through batches of the formulae in the NOMAD data set. Having a combination of a chemical distance metric, density-aware dimensionality reduction, clustering, and a regression model, the DiSCoVeR algorithm serves as a tool to identify and assess these superconducting compositions [1]. This research and implementation resulted in the screening of chemically novel compositions exhibiting critical temperatures upwards of 150 K, which correlates to superconductors in the cuprate class. This implementation demonstrates a process of performing machine learning-assisted superconductor screening (while exploring chemically distinct spaces) which can be utilized in the materials discovery process.

Development of YBCO Patterned Multi-Filamentary Film Using Photolithography Method

Abstract: High-temperature superconducting (HTS)-coated conductors (CCs) can be applied to magnets under low temperature and high magnetic field conditions, as well as in electric power equipment. Reducing the screening current and AC loss is an important topic for practical applications. In this study, we propose a multifilamentary YBCO thin film, fabricated by depositing YBCO on a substrate with elevated Zr stripes patterned by using photolithography techniques. While the thin film exhibited superconductivity, the crystal grain orientation was disturbed above the stripe, which locally inhibited the superconducting current flow. The results of this study indicate that a continuous YBCO film can be dividing into separate superconducting filaments by locally suppressing the good grain alignment required for a high intergrain J _c with Zr stripes between the STO substrate and the YBCO film.

Stability criterion for a composite high-temperature tape/film superconductor

Abstract: The stability of a tape or film type high-critical-temperature superconductor of a large aspect ratio is studied by considering the transverse normal zone behavior across a cross-section subjected to an instantaneous and concentrated thermal disturbance. Different performance in terms of stable superconducting operation, current sharing, quenching, and superconductivity recovery have been identified. A stability criterion was developed based on heat conduction analyses for the current sharing steady state and the quenching steady state. The criterion was validated by the transient stability behavior results for a YBa₂Cu₃O_7−x superconductor obtained through finite difference method. The effect of disturbance energy on the stability performance was also investigated.

AC Loss Estimation Model for High-Temperature Superconducting Cables Derived From Experiments Simulating Electromagnetic Environments

Abstract: In a previous study, the AC loss characteristics of each layer of a high-temperature superconducting (HTS) AC cable were experimentally investigated [1]–[3]. Based on these data, we modeled the AC loss in a superconducting cable by considering the maxi-mum and minimum values of the loss. A comparison between this model and the experimental data showed good agreement. Hence, it is possible to estimate AC loss under electromagnetic conditions in a high-temperature superconducting cable. This model makes it possible to determine the losses of each layer in the superconducting cable and to design the minimum AC loss load of the superconducting cable. This model estimates the AC losses of a three-layer twisted HTS cable.

Flux Noise Reduction of HTS-SQUIDs via Introduction of Antidots

Abstract: High- T _C superconducting quantum interference devices (HTS-SQUID), which can be used at near liquid nitrogen temperature, allow for reduction of the SQUID equipment both size and operating costs. However, the noise of HTS-SQUID, which consists of white and 1/f noise is higher than that of low- T _C SQUID. The 1/f noise, particularly prominent in HTS devices, is generated by fluctuations of the critical current in the Josephson junction and by the motion of the magnetic flux trapped in the superconducting thin film. Presence of low-frequency noise is a problem especially in HTS-SQUID applications such as bioinstrumentation, environmental measurement, and magnetic contamination inspection. Nanoscale holes (antidots) in HTS films are known to attract and pin magnetic flux. In this study, we investigate the effect of artificially introduced nanoscale antidots near the junction boundaries on the noise characteristics of bicrystal SQUIDs. We used focused ion beam irradiation to create in YBa ₂ Cu ₃ O _{7- δ} (YBCO) thin film holes of about 90 nm in diameter. As a result of the antidots introduction, the 1/f noise of the bicrystal SQUID in a magnetic field of 66 μT at 77 K was significantly reduced.

High-Temperature Superconducting Interconnects for Ultra-Low Temperature, High-Field Environments

Abstract: Coplanar (with the ground) 20 cm long waveguides are manufactured from the YBCO-on-Kapton material. We inves-tigate the effect of parasitic ground plane resonances on the per-formance of these waveguides. It is concluded that dense rows stitching vias are essential for isolating the lines to a level below 60 dB at 6 GHz. We demonstrate a metalized via technology that is compatible with both the traditional Flexible Printed Circuit (FPC) process and the epitaxial YBCO material. Stitching via fence with the via period 10 mm is shown as effective in suppress-ing parasitic resonances at 77 K.

The prospects of high-temperature superconductors

Abstract: Description Overcoming cost barriers could make high-temperature superconductors pervasive Superconductors conduct electricity with essentially zero resistance, avoiding many of the power losses in present electric power transmission, conversion, and use. Strong electromagnetic fields have so far been the principal application of superconductors, with widespread commercial superconductivity limited to magnetic resonance imaging (MRI) electromagnets composed of the low-temperature superconductor (LTS) Nb47Ti. Broader applications of LTSs have been hindered by the need to cool them with liquid helium (at or below 4.2 K). High-temperature superconductors (HTSs) (1) that can operate at liquid nitrogen temperatures (between 65 and 80 K) promised ubiquitous applications that could escape the constraint of LTSs. Achieving the International Energy Agency roadmap to carbon-free economies by 2050 would be greatly facilitated by the use of nuclear fusion-generated electricity. HTSs have been used in prototype nuclear fusion reactors (2), thereby creating the opportunity to overcome the cost barriers that have so far prevented the commercial development of HTS technologies.

Discovering Chemically Novel, High-Temperature Superconductors

Abstract: One of the biggest unsolved problems in condensed matter physics is what mechanism causes high-temperature superconductivity and if there is a material that can exhibit superconductivity at both room temperature and atmospheric pressure. Among the many important properties of a superconductor, the critical temperature (Tc) or transition temperature is the point at which a material transitions into a superconductive state. In this implementation, machine learning is used to predict the critical temperatures of chemically unique compounds in an attempt to identify new chemically novel, high-temperature superconductors. The training data set (SuperCon) consists of known superconductors and their critical temperatures, and the testing data set (NOMAD) consists of around 700,000 novel chemical formulae. The chemical formulae in these data sets are first passed through a collection of rapid screening tools, SMACT, to check for chemical validity. Next, the DiSCoVeR algorithm is used to train on the SuperCon data to form a model, and then screens through batches of the formulae in the NOMAD data set. Having a combination of a chemical distance metric, density-aware dimensionality reduction, clustering, and a regression model, the DiSCoVeR algorithm serves as a tool to identify and assess these superconducting compositions [1]. This research and implementation resulted in the screening of chemically novel compositions exhibiting critical temperatures upwards of 150 K, which correlates to superconductors in the cuprate class. This implementation demonstrates a process of performing machine learning-assisted superconductor screening (while exploring chemically distinct spaces) which can be utilized in the materials discovery process.