Science Alert April 27, 2022 An international team of researchers (Germany, China, the Netherlands, USA – Johns Hopkins University) 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 was proved through the Fraunhofer pattern. They achieved stable half-wave rectification of a square-wave excitation with a very low switching current density, high rectification ratio and high […]
Category Archives: Superconductor
Study raises new possibilities for triggering room-temperature superconductivity with light
Phys.org February 9, 2022 An international team of researchers (South Korea, USA – SLAC National Accelerator Laboratory, Germany, Japan) explored a photoinduced normal state of YBCO through a charge density wave (CDW) with time-resolved resonant soft x-ray scattering, as well as a high magnetic field x-ray scattering. In the nonequilibrium state where people predict a quenched superconducting state based on the previous optical spectroscopies, they experimentally observed a similar analogy to the competition between superconductivity and CDW shown in the equilibrium state. Their results provide a critical clue that the characteristics of the photoinduced normal state show a solid resemblance […]
Redrawing the lines: Growing inexpensive, high-quality iron-based superconductors
Phys.org December 17, 2021 The technique of ion irradiation to enhance the dissipation-free supercurrent in the presence of a magnetic field for type II superconductors is complicated and expensive. An international team of researchers (Japan, USA – Florida State University) has developed an inexpensive, scalable way to produce high-temperature superconductors using grain boundary engineering techniques. They grew iron-based superconductors (FBS) called “potassium-doped BaFe2As2 (Ba122) using molecular beam epitaxy, in which the superconductor is grown on a substrate. It had high pinning efficiency without artificial pinning centers (APCs). Measurements of the thin film’s electrical resistivity and magnetic properties showed that the […]
Potential step toward new superconductors
Nanowerk December 2, 2021 An international team of researchers (USA – Harvard University, Spain, Finland) describe for the first time an unexpected path electrons can take through 2D, highly structured materials: That path is called branched flow. Branched flow has been seen in 3D, chaotic systems like gases, tsunamis, and even light ricocheting through soap bubbles but nobody expected to see branched flow in 2D periodic systems. The challenge is controlling the branched flow. However, if scientists learn to control the newly discovered branched flow, they won’t need phonons; they can matchmake the electrons themselves through their custom superwires and […]
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 […]
Researchers discover unusual competition between charge density wave and superconductivity
Phys.org July 5, 2021 To study the layered cage structure superconductor CsV3Sb5, which has a charge density wave (CDW) transition temperature of 94 K, researchers in China conducted high-pressure electrical transport and magnetic susceptibility measurements. They found that the CDW transition is monotonically suppressed by pressure, and superconductivity is enhanced with increasing pressure up to P1 ≈ 0.7 GPa. They found an unexpected suppression of superconductivity until pressure around 1.1 GPa, after that, Tc was enhanced with increasing pressure again. The CDW was completely suppressed at a critical pressure P2 ≈ 2 GPa together with a maximum Tc of about 8 K. The pressure-dependent Tc showed an unexpected […]
Researchers uncover unique properties of a promising new superconductor
Science Daily June 16, 2021 An international team of researchers (USA – University of Minnesota, Pennsylvania State University, Cornell University, National High Magnetic Field Laboratory, China, Switzerland) found that Niobium diselenide (NbSe2) in 2D form is a more resilient superconductor because it has a two-fold symmetry, which is very different from thicker samples of the same material. Despite the six-fold structure, it only showed two-fold behavior in the experiment. They attributed the newly discovered two-fold rotational symmetry of the superconducting state in NbSe2 to the mixing between two closely competing types of superconductivity, namely the conventional s-wave type — typical of […]
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 […]
Scientists watch 2D puddles of electrons emerge in a 3D superconducting material
Science Daily April 12, 2021 An international team of researchers (USA – SLAC National Accelerator Laboratory, Stanford University, Colombia) synthesized high-temperature superconductor BPBO (Barium, Lead, Bismuth, Oxygen) and tested its properties, including transition temperature. The data showed electrons behaving as if they were confined to ultrathin, 2D layers or stripes within the material. The stripes were layers where electrons behave as if they are confined to 2D, puddle-like areas in the material. The distances between the puddles were short enough to allow them to behave like a superconductor. The 2D puddles emerged as the scientists carefully adjusted the temperature and […]
Discovery of a mechanism for making superconductors more resistant to magnetic fields
Phys.org March 30, 2021 Researchers in Japan discovered that when the crystalline films of indium is thinned to a two-dimensional atomic layer, the spin, and the momentum of the electrons in the layer are coupled, causing the electron spins to frequently rotate. This offsets the effect of the changes in electronic energy induced by the magnetic field and thus preserves superconductivity. This mechanism can enhance the critical magnetic field up to 16-20 Tesla, which is approximately triple the generally accepted theoretical value. It is expected to have a wide range of applications as it was observed for an ordinary superconducting […]