Nanowerk April 27, 2022 Showing magnetic-field-free, single-directional superconductivity with Josephson coupling, it would serve as the building block for next-generation superconducting circuit technology. An international team of researchers (Germany, China, the Netherlands, USA – Princeton University, Johns Hopkins University) has fabricated an inversion symmetry breaking van der Waals heterostructure of NbSe2/Nb3Br8/NbSe2. They demonstrated that even without a magnetic field, the junction can be superconducting with a positive current while being resistive with a negative current. The ΔIc behaviour (the difference between positive and negative critical currents) with magnetic field is symmetric and Josephson coupling is proved through the Fraunhofer pattern. […]
Tag Archives: Superconductivity
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 […]
A-list candidate for fault-free quantum computing delivers surprise
Science Daily December 22, 2021 Spin-triplet pairing is important because it can host topological states and majorana fermions relevant for quantum computation. Because spin-triplet pairing is usually mediated by ferromagnetic (FM) spin fluctuations, uranium-based materials near an FM instability are ideal candidates for realizing spin-triplet superconductivity. UTe2 has been identified as a candidate for a chiral spin-triplet topological superconductor near an FM instability, although it also has antiferromagnetic (AF) spin fluctuations. A team of researchers in the US (Rice University, Florida State University, Oak Ridge National Laboratory, UC San Diego, Arizona State University) used inelastic neutron scattering (INS) to show […]
New material could be two superconductors in one
MIT News November 15, 2021 An international team of researchers (USA – MIT, Rutgers University, National High Magnetic Field Laboratory, Harvard University, Japan) synthesized layered superconductor Ba6Nb11S28. Instead of via one electron a superconductor carries charge by two electrons bound together in a Cooper pair. By applying an in-plane magnetic field, they observed an abrupt, partial suppression of diamagnetism below the upper critical magnetic field, which is suggestive of an emergent phase within the superconducting state. It turns out this kind of superconductor can be manipulated to form a variety of unusual patterns as Cooper pairs move between Landau levels. […]
A new dimension in magnetism and superconductivity launched
Science Daily November 3, 2021 In recent studies the impact of curvilinear geometry enters various disciplines, ranging from solid-state physics over soft-matter physics, chemistry, and biology to mathematics. An international team of researchers (Germany, Austria) summarized the state of the art and prospects for future research in curvilinear solid-state systems exhibiting such fundamental cooperative phenomena as ferromagnetism, antiferromagnetism, and superconductivity. Highlighting the recent developments and current challenges in theory, fabrication, and characterization of curvilinear micro- and nanostructures, with emphasis on perspective research directions entailing new physics and to their strong application potential. They aim to cross the boundaries between the […]
Unmasking the magic of superconductivity in twisted graphene
Science Daily October 20, 2021 An international team of researchers (USA – Princeton University, Japan) combined tunnelling and Andreev reflection spectroscopy with the scanning tunnelling microscope to observe several key experimental signatures for unconventional superconductivity in magic angle twisted bilayer graphene (MATBG). They showed that the tunnelling spectra below the transition temperature Tc are inconsistent with those of a conventional s-wave superconductor, but rather resemble those of a nodal superconductor with an anisotropic pairing mechanism. They observed a large discrepancy between the tunnelling gap which far exceeds the mean-field BCS ratio, and the gap extracted from Andreev reflection spectroscopy. The […]
Magnetic field turns handed superconductor into liquid crystal-like nematic state
Nanowerk September 15, 2021 Recent measurements of the resistivity in magic-angle twisted bilayer graphene near the superconducting transition temperature show twofold anisotropy, or nematicity, when changing the direction of an in-plane magnetic field. This was interpreted as strong evidence for exotic nematic superconductivity instead of the widely proposed chiral superconductivity. An international team of researchers (Germany, USA – the Flatiron Institute, Spain) has suggested a surprising connection between the nematic behavior of a superconductor in a magnetic field and its spiral-like ground state in the absence of the field. Their theory could not only explain recent experiments on twisted bilayer […]
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
The demonstration of ultrafast switching to an insulating-like metastable state
Phys.org July 13, 2021 Superconductors host collective modes that can be manipulated with light. An international team of researchers (Japan, France) has shown that a strong terahertz light field can induce oscillations of the superconducting order parameter in NbN with twice the frequency of the terahertz field. The result can be captured as a collective precession of Anderson’s pseudospins in ac driving fields. A resonance between the field and the Higgs amplitude mode of the superconductor then results in large terahertz third-harmonic generation. Their method paves a way toward nonlinear quantum optics in superconductors with driving the pseudospins collectively and […]