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  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  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

Closely spaced hydrogen atoms could facilitate superconductivity in ambient conditions  February 3, 2020 An international team of researchers (Switzerland, USA – University of Illinois, Oak Ridge National Laboratory, Poland) conducted neutron scattering experiments on zirconium vanadium hydride at atmospheric pressure and at temperatures from -450 degrees Fahrenheit to as high as -10 degrees Fahrenheit and observed hydrogen-hydrogen atomic distances in the metal hydride, as small as 1.6 angstroms, compared to the 2.1 angstrom distances predicted for these metals. Computer simulations of the data proved conclusively that the unexpected spectral intensity occurs only when distances between hydrogen atoms are closer than 2.0 angstroms. The findings could possibly facilitate superconductivity at […]

Suspended layers make a special superconductor  November 5, 2019 Researchers in the Netherlands created a suspended double layer of molybdenum disulfide with an ionic liquid on both sides that can be used to create an electric field across the bilayer. In the individual monolayer, such a field will be asymmetric, with positive ions on one side and negative charges induced on the other. However, in the bilayer, they could have the same amount of charge induced at both monolayers, creating a symmetrical system. The electric field that was thus created could be used to switch superconductivity on and off. This means that a superconducting transistor […]

Scientists finally find superconductivity in place they have been looking for decades  September 26, 2019 The biggest obstacle to making superconductors operate at higher temperatures and making superconductivity more robust has been the lack of a model. High-temperature superconductors are quantum materials, where electrons cooperate to produce unexpected properties. A team of researchers in the US (Stanford University, SLAC National Accelerator Laboratory) created a virtual version of a cuprate on a square lattice, like a wire fence with square holes where each virtual atom can accommodate at most two electrons that are free to jump or hop—either to their immediate neighbors on the square lattice or diagonally across each square. When […]

Light pulses provide a new route to enhance superconductivity  March 4, 2019 Under normal electron band theory, Mott insulators ought to conduct electricity, but they do not due to interactions among their electrons. An international team of researchers (Japan, Italy) used numerical methods to show that pulses of light could be used to turn these materials beyond simple conductors to superconductors due to an unconventional type of superconductivity known as “eta pairing” which is thought to involve repulsive interactions between certain electrons within the structure. The research provides new insights not only into the phenomenon of non-equilibrium dynamics but could lead to the development of new high-temperature superconductors…read […]

Physicists uncover new competing state of matter in superconducting material

Science Daily  January 2, 2019 Using ultrafast terahertz pump-probe a team of researchers in the US (Iowa State University, University of Alabama) found an unusual out-of-equilibrium Cooper pair nonlinear dynamics and a nonequilibrium state in iron pnictides. They identified long prebottleneck dynamics that are sensitive to both doping and temperature. According to the researchers the buildup of excitonic interpocket correlation between electron-hole quasiparticles quenches superconductivity after photoexcitation leading to a long-lived, many-quasiparticle excitonic state. Findings help create better superconducting electronics and energy-efficient devices…read more. TECHNICAL ARTICLE

Graphene on the way to superconductivity

Science Daily  November 9, 2018 Previously researchers at MIT showed that it is possible to generate a form of superconductivity in a system of two layers of graphene under very specific conditions using a complex method. Researchers in Germany have developed a simpler technique by heating silicon carbide crystal until silicon atoms evaporate from the surface, leaving first a single-layer of graphene on the surface, and then a second layer of graphene. The two graphene layers are not twisted against each other but lie exactly on top of each other. They argue that their two-dimensional flat band model and the […]