Phys.og September 22, 2022 The interplay between charge order and superconductivity remains one of the central themes of research in quantum materials. In the case of cuprates, the coupling between striped charge fluctuations and local electromagnetic fields is especially important, as it affects transport properties, coherence, and dimensionality of superconducting correlations. An international team of researchers (Germany, USA – Harvard University, Brookhaven National Laboratory, Switzerland, UK) studied the emission of coherent terahertz radiation in single-layer cuprates of the La2-xBaxCuO4 family, for which this effect is expected to be forbidden by symmetry. They found that emission vanishes for compounds in which […]
Tag Archives: Superconductors
A proof of odd-parity superconductivity
Phys.org July 12, 2022 Odd-parity superconductivity is rare in nature; only a few materials support this state, and in none of them has the expected angle dependence been observed. CeRh2As2 was recently found to exhibit two superconducting states: A low-field state changes into a high-field state at 4 T when a magnetic field is applied along one axis. Through a comprehensive study of the angle dependence of the upper critical fields using magnetic ac susceptibility, specific heat, and torque on single crystals of CeRh2As2 an international team of researchers (Germany, New Zealand, France, USA – University of Wisconsin) has shown […]
Researchers find a way to form diodes from superconductors
Science Daily May 11, 2022 An international team of researchers (Italy, Spain, USA – MIT) has developed the quasi-particle counterpart, a superconducting tunnel diode with zero conductance in only one direction. The direction-selective propagation of the charge was obtained through the broken electron-hole symmetry induced by the spin selection of the ferromagnetic tunnel barrier: a EuS thin film separating a superconducting Al and a normal metal Cu layer. The Cu/EuS/Al tunnel junction achieved a large rectification (up to ∼40%) already for a small voltage bias (∼200 μV) due to the small energy scale of the system. With the help of an […]
Study shows how superconductivity can be switched on and off in superconductors
Phys.org March 30, 2022 Recent experiments have suggested that superconductivity in metallic nanowires can be suppressed by the application of modest gate voltages. The source of this gate action has been debated and either attributed to an electric-field effect or to small leakage currents. An international team of researchers (Switzerland, Italy, USA – IBM, NY) has shown that the suppression of superconductivity in titanium nitride nanowires on silicon substrates does not depend on the presence or absence of an electric field at the nanowire but requires a current of high-energy electrons. The suppression is most efficient when electrons are injected […]
Magnetism helps electrons vanish in high-temp superconductors
Phys.org March 10, 2022 In high-temperature superconductors, at a certain “critical point,” electrons seem to vanish from the Fermi surface map. To understand this phenomenon and engineer that property into some other material that is easier to adopt in technologies, an international team of researchers (USA – Cornell University, UT Austin, National High Magnetic Field Laboratory, Binghamton University, Canada, France, UK) discovered that magnetism is key to understanding the behavior of electrons in “high-temperature” superconductors. They measured the Fermi surface of a copper-oxide high temperature superconductor as a function of electron concentration, right around the critical point and found that […]
Study raises new possibilities for triggering room-temperature superconductivity with light
Phys.org March 9, 2022 In the case of the superconducting material yttrium barium copper oxide, or YBCO, experiments have shown that under certain conditions, knocking it out of equilibrium with a laser pulse allows it to superconduct at much closer to room temperature than researchers expected. YBCO switches from a normal to a superconducting state when chilled below a certain transition temperature or it can be switched off with a pulse of light. An international team of researchers (South Korea, USA – SLAC National Accelerator Laboratory, Japan, Germany) compared the two switching approaches (exposing to high magnetic field and laser […]
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 […]
Discovery of two-phase superconductivity in CeRh2As2
Science Daily August 26, 2021 Although tens of unconventional superconductors have been discovered in the past half century, there was good thermodynamic evidence of more than one superconducting phase in only one or two materials. An international team of researchers (Germany, New Zealand, UK) used thermodynamic probes to establish two-phase superconductivity in CeRh2As2. Both materials have the highest critical magnetic field to superconducting transition temperature ratio of any known superconductor. The findings can be expected to generate entirely new research directions…read more. TECHNICAL ARTICLE
Scientists have synthesized a new high-temperature superconductor
Phys.org March 10, 2021 An international team of researchers (Russia, USA – University of Chicago, Spain, Italy, China) performed theoretical and experimental research on yttrium hydride (YH6), one among the three highest-temperature superconductors known to date. All these hydrides reach their maximum superconductivity temperatures at very high pressures. The current challenge is to attain room-temperature superconductivity at lower pressures. In the case of YH6, the agreement between theory and experiment is rather poor. For example, the critical magnetic field observed in the experiment is 2 to 2.5 times greater as compared to theoretical predictions. This is the first-time scientists encounter such […]
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 […]