Phys.org April 8, 2024 Magnetism can cause a modulation of superconducting pairing in real space in both copper-based and iron-based materials. Researchers in China reported on the discovery of a spatially varying superconducting state residing at the interface between KTaO3 and ferromagnetic EuO. Electrical transport measurements revealed different values of the critical temperature and magnetic field at which the superconductivity breaks down when current was applied along the two orthogonal in-plane directions. This anisotropy occurred in low-carrier-density samples that were characterized by strong coupling between the Ta 5d and Eu 4f electrons, whereas in high-carrier-density samples, the coupling was weakened, […]
Category Archives: Superconductivity
Tracking unconventional superconductivity
Science Daily January 31, 2024 In order to better understand the field-resistant superconducting phase, an international team of researchers (Germany, Japan, France) conducted magnetic-torque and magnetotransport measurements in pulsed magnetic fields. They determined the record-breaking upper critical field of ?0Hc2???73?T and its evolution with angle. The normal-state Hall effect experiences a drastic suppression indicative of a reduced band polarization above Hm in the angular range around 30° caused by a partial compensation between the applied field and an exchange field. According to the researchers this promotes the Jaccarino-Peter effect as a likely mechanism for the reentrant superconductivity above Hm… read […]
Physicists coax superconductivity and more from quasicrystals
Phys.org September 28, 2023 Owing to their complexity and scarcity, quasicrystals are underexplored relative to periodic and amorphous structures. An international team of researchers (USA – MIT, Japan, Israel) introduced a new type of highly tunable quasicrystal easily assembled from periodic components. By twisting three layers of graphene with two different twist angles, they formed two mutually incommensurate moiré patterns. In contrast to many common atomic-scale quasicrystals, the quasiperiodicity in their system was defined on moiré length scales of several nanometres. This ‘moiré quasicrystal’ allowed them to tune the chemical potential and thus the electronic system between a periodic-like regime […]
Replication of room-temperature superconductor claims fails to show superconductivity
Phys.org May 17, 2023 Researchers in China attempting to replicate the superconductivity results from an experiment conducted by a team at the University of Rochester (UoR) doping a lutetium-hydrogen chemical with nitrogen. The team in China found that the process did lead to the formation of a compound that at first glance appeared to be identical to that created by the team at UoR. A closer look using energy dispersive X-ray spectroscopy showed its structure, a hydrogen-lutetium-nitrogen compound, that looked nearly identical to the UoR compound. The Chinese team even found the same color changes reported by the UoR team […]
Towards a sustainable superconductor technology with magnesium diboride super magnets
Phys.org May 1, 2023 Magnesium diboride (MgB2), a binary compound, behaves as a superconductor at a moderate temperature of around 39 K (-234°C). It can replace conventional low-temperature superconductors. However, it suffers from weak magnetic flux pinning. To enhance pinning, it is essential to tune the pinning centers in MgB2—the boundaries of grains or small crystals that constitute MgB2. An international team of researchers (Japan, Czech Republic) used high-energy ultra-sonication for refining coarse B powder dispersed in 2-propanol up to nanoscale sizes. Utrasonic vibrations imparted high speeds to B particles in the solvent, leading to collisions. The resulting friction and […]
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 […]
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 […]
Exploring the bounds of room-temperature superconductivity
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 […]
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 […]