Science Daily March 9, 2022 Several reports of high superconducting transition temperature (Tc) up to 287 K in hydrides under pressure of up to 267 GPa have appeared. The ultrahigh pressure needed to create the high-temperature superconductivity (HTS) in hydrides has hampered the detailed study of the high-pressure-induced high-Tc superconductivity state, as well as any potential applications. Researchers at the University of Houston developed a pressure-quench process (PQP) and demonstrated it successfully in stabilizing at ambient the high-pressure-induced superconducting phases and other phases in the non-superconducting element Sb, the binary superconducting compound FeSe, and the non-superconducting compound Cu-doped FeSe. According […]
Category Archives: Superconductivity
Moments of silence point the way towards better superconductors
Science Daily December 20, 2021 Superconductivity depends on the presence of electrons bound together in a Cooper pair, but they break dissipating into two quasiparticles that hamper the performance of superconductors. It is not clear why Cooper pairs break, but the presence of quasiparticles introduces noise into technologies based on superconductors. Through an experimental set up an international team of researchers (Finland, Sweden) showed that in micron-scale aluminium superconductor separated from metallic copper by a thin insulating layer, the broken Cooper pairs the quasiparticles would tunnel through the insulation to the copper. The Cooper pairs break in bursts, with seconds […]
Electron family creates previously unknown state of matter
Science Daily November 5, 2021 What distinguishes a superconducting state from a normal state is a spontaneously broken symmetry corresponding to the long-range coherence of pairs of electrons, leading to zero resistivity and diamagnetism. An international team of researchers (Germany, Sweden, Japan, France) was investigating the superconducting metal Ba1-xKxFe2As2 from the class of iron pnictides when they discovered that four electrons instead of two were forming a bond. It was scrutinized for two years using seven different methods to confirm the result. All data were consistent with the same result. Thus, they concluded that the four-particle electron family in certain […]
The pressure is off and high temperature superconductivity remains
Phys.org July 8, 2021 The grand challenge in superconductivity research and development is no longer restricted to further increasing the superconducting transition temperature under extreme conditions and must now include concentrated efforts to lower, and better yet remove, the applied pressure required. An international team of researchers (USA – Houston University, Rice University, China) has shown such a possibility in the pure and doped high-temperature superconductor FeSe by retaining, at ambient pressure via pressure quenching, its Tc up to 37 K and other pressure-induced phases. They observed that some phases remain stable without pressure at up to 300 K and […]
Superconductivity, high critical temperature found in 2D semimetal tungsten nitride
Phys.org May 5, 2021 Researchers in Switzerland used first-principles calculations to identify intrinsic superconductivity in monolayer W2N3, a material that has recently been identified as being easily exfoliable from a layered hexagonal-W2N3 bulk by calculations, a theory also supported by experimental evidence. They found a critical temperature of 21 K, that is, just above liquid hydrogen and a record-high transition temperature for a conventional phonon-mediated 2D superconductor. According to the researchers the material could be doped such that currently unoccupied helical edge states 0.5 eV above the Fermi level become filled, even while superconductivity persists making W2N3 a viable candidate […]
New 2D superconductor forms at higher temperatures than ever before
Phys.org April 27, 2021 The distinctive electronic structure found at interfaces between materials can allow unconventional quantum states to emerge. An international team of researchers (USA – Argonne National Laboratory, University of Illinois, China) has discovered superconductivity in electron gases formed at interfaces between (111)-oriented KTaO3 and insulating overlayers of either EuO or LaAlO3. The superconducting transition temperature, as high as 2.2 kelvin, is about one order of magnitude higher than that of the LaAlO3/SrTiO3 system. Similar electron gases at KTaO3 (001) interfaces remain normal down to 25 millikelvin. The critical field and current-voltage measurements indicated that the superconductivity is […]
Room-temperature superconductor? Rochester lab sets new record toward long-sought goal
University of Rochester October 14, 2020 A team of researchers in the US (University of Rochester, industry, University of Nevada) reported superconductivity in a photochemically transformed carbonaceous sulfur hydride system, starting from elemental precursors, with a maximum superconducting transition temperature of 287.7 ± 1.2 kelvin (about 15 degrees Celsius) achieved at 267 ± 10 gigapascals. The superconducting state was observed over a broad pressure range in the diamond anvil cell. Superconductivity was established by the observation of zero resistance, a magnetic susceptibility of up to 190 gigapascals, and reduction of the transition temperature under an external magnetic field of up […]
Superconductivity with a twist explained
Phys.org September 29, 2020 An international team of researchers (Switzerland, Spain, the Netherlands, Italy, Japan) has shown that the interplay between the two hexagonal carbon lattices, slightly twisted, causes a much larger hexagonal moiré pattern to emerge. By creating this new periodicity, the interaction between the electrons changes, yielding “slow” electrons enabling superconductivity. At a temperature of 1.7 Kelvin, twisted bilayer graphene conducts electricity without resistance. The researchers have finally confirmed the mechanism behind these fascinating new superconductors…read more. TECHNICAL ARTICLE
New type of superconductor identified
Science Daily September 21, 2020 Strontium ruthenate (Sr2RuO4) has stood as the leading candidate for a spin-triplet superconductor for 26 years. Using resonant ultrasound spectroscopy an international team of researchers (USA – Cornell University, Florida State University, Germany, Japan) measured the entire symmetry-resolved elastic tensor Sr2RuO4 through the superconducting transition. They found a thermodynamic discontinuity in the shear elastic modulus which implies that the superconducting order parameter has two components, a two-component p-wave order parameter. As this order parameter appears to have been precluded by recent NMR experiments, they suggest that two other two-component order parameters are now the prime […]
Scientists created an ‘impossible’ superconducting compound
Phys.org March 3, 2020 An international team of researchers (China, Russia) successfully synthesized praseodymium superhydrides (PrHg) and showed the emergence of a possible superconducting transition (Tc) below 9 K and Tc dependent on the applied magnetic field. Theoretical calculations indicated that magnetic order and likely superconductivity coexist in a narrow range of pressures in the PrHg sample, which may contribute to its low superconducting temperature. The results highlight the intimate connections between hydrogenic sublattices, density of states, magnetism, and superconductivity in Pr-based superhydrides…read more. Open Access TECHNICAL ARTICLE