Phys.org December 5, 2024 Although this high Tc is thought to be associated with electron–phonon coupling (EPC), the microscopic coupling mechanism and its role in the superconductivity remain elusive. An international team of researchers (USA – UC Irvine, Princeton University, China, Sweden) atomically resolved the phonons at the FeSe/STO interface and uncovered new optical phonon modes, coupling strongly with electrons, in the energy range of 75–99 meV. These modes were characterized by out-of-plane vibrations of oxygen atoms in the interfacial double-TiOx layer and the apical oxygens in STO. Their results demonstrated that the EPC strength and superconducting gap of 1 uc FeSe/STO […]
Tag Archives: Superconductors
In step forward for quantum computing hardware, IU physicist uncovers novel behavior in quantum-driven superconductors
EurekAlert November 12, 2024 An international team of researchers (India, USA – Indiana University) studied the transport signatures of unpaired Floquet Majorana fermions in the Josephson current of weakly linked, periodically driven topological superconductors. They obtained analytical expressions for the occupation of the Floquet Majorana fermions in the presence of weak coupling to thermal reservoirs, and showed that, similar to undriven topological superconductors, for sufficiently low temperatures and large systems the Josephson current involving Floquet Majorana fermions is in the phase difference across the junction and depends linearly on the coupling between superconductors. Unlike the static case, the amplitude of […]
Research team uses terahertz pulses of light to shed light on superconducting disorder
Phys.org September 16, 2024 Inhomogeneities crucially influence the properties of quantum materials, yet methods that can measure them remain limited and can access only a fraction of relevant observables. However, complementary techniques that can resolve higher-order correlations are needed to elucidate the nature of the inhomogeneities. And local tunnelling probes are often effective only far below the critical temperature. An international team of researchers (Germany, USA – Brookhaven, Harvard University, Cornell University, Stony Brook University, Switzerland, UK) developed a two-dimensional terahertz spectroscopy method to measure Josephson plasmon echoes from an interlayer superconducting tunnelling resonance in a near-optimally doped cuprate. The […]
Researchers observe ‘locked’ electron pairs in a superconductor cuprate
Phys.org August 15, 2024 Copper oxide materials can be made superconducting by doping the parent compound with either electrons or holes. Hole-doped cuprates typically have higher transition temperatures and have been studied more extensively. An international team of researchers (SLAC National Accelerator Laboratory, Yale University, UC Berkeley, Sweden) observed an unusual energy gap in electron-doped cuprate Nd2-xCexCuO4 high above the temperature of the superconducting transition. After considering all the known ordering tendencies in tandem with the phase diagram, they hypothesized that the normal-state gap in the underdoped n-type cuprates originated from Cooper pairing. According to the researchers the high temperature […]
Researchers advance topological superconductors for quantum computing
Nanowerk September 21, 2023 The interface between 2D topological Dirac states and an s-wave superconductor is expected to support Majorana-bound states (MBS) that can be used for quantum computing applications. Realizing these novel states of matter and their applications requires control over superconductivity and spin-orbit coupling to achieve spin-momentum-locked topological interface states (TIS) which are simultaneously superconducting. A team of researchers in the US (Oak Ridge National Laboratory, Rutgers State University of New Jersey) have shown superconductivity in monolayer (ML) FeTe1–ySey (Fe(Te,Se)) grown on Bi2Te3 by molecular beam epitaxy (MBE). Spin and angle-resolved photoemission spectroscopy (SARPES) directly resolved the interfacial […]
Team creates simple superconducting device that could dramatically cut energy use in computing
Phys.org July 28, 2023 Accomplishing unequal supercurrents in the forward and backward directions in superconductors would enable unprecedented functionalities. This nonreciprocity of critical supercurrents is called the superconducting (SC) diode effect. An international team of researchers (USA – MIT, US Army DEVCOM, High School (Alabama, Washington). Switzerland, Spain) demonstrated the strong SC diode effect in conventional SC thin films, such as niobium and vanadium, employing external small magnetic fields. Interfacing the SC layer with a ferromagnetic semiconductor EuS, they further accomplished the nonvolatile SC diode effect reaching an efficiency of 65%. By careful control experiments and theoretical modeling, they demonstrated […]
Researchers achieve interdimensional superconductivity
Nanowerk July 19, 2023 Spatial disorder has been shown to drive two-dimensional (2D) superconductors to an insulating phase through a superconductor–insulator transition (SIT). Numerical calculations predict that with increasing disorder, emergent electronic granularity is expected in these materials—a phenomenon where superconducting (SC) domains on the scale of the material’s coherence length are embedded in an insulating matrix and coherently coupled by Josephson tunneling. An international team of researchers (USA – SLAC National Accelerator Laboratory, Colombia) has shown spatially resolved scanning tunneling spectroscopy (STS) measurements of the three-dimensional (3D) superconductor BaPb1−xBixO3 (BPBO), which surprisingly demonstrated three key signatures of emergent electronic […]
The exciting possibilities of tiny, twisted superconductors
Phys.org May 5, 2023 A team of researchers in the USA (Rutgers University, Harvard University, University of Connecticut, Louisiana State University, Flatiron Institute, Princeton University) proposed how to experimentally manipulate the quasiparticles, in very thin layers of ordinary superconductors to create topological superconductors by slightly twisting the stacked layers. They theorized that the application of a current makes the quasiparticles in the superconductor behave as if they were in a topological superconductor. They theorized that the twist at any angle essentially determines the properties. Even deviations by .1 degree in twist is strongly detrimental. The interactions between quasiparticles are shown […]
Electrons take new shape inside unconventional metal
Phys.org January 10, 2023 After an extensive study of the angular dependence of quantum oscillations (QOs) in the electrical conductivity of YPtBi an international team of researchers (USA – University of Maryland, Missouri University of Science and Technology, Rutgers University, Canada) has reported an anomalous Shubnikov–de Haas effect consistent with the presence of a coherent j=3/2 Fermi surface. The QO signal in YPtBi manifested an extreme anisotropy upon rotation of the magnetic field from the [100] to [110] crystallographic direction, where the QO amplitude vanished. According to the researchers this radical anisotropy for such a highly isotropic system cannot be […]
The magneto-optic modulator
EurekAlert September 16, 2022 Superconducting microprocessors and quantum computers promise to revolutionize computation, but ultra-cold components must interface with ambient temperature systems. An international team of researchers (USA – UC Santa Barbara, industry, Italy, UK, Japan) has built a device that translates electrical input into pulses of light. An electric current creates a magnetic field that changes the refractive index of a synthetic garnet making it possible to tune the amplitude of the light that circulates in a micro-ring resonator. This creates bright and dark pulses that carry information through the fiberoptic cable. The modulator operates at wavelengths of 1,550 […]