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Field-induced electronic phase separation in the high-temperature superconductor La 1.94 Sr 0.06 CuO 4 + y
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Signatures of Majorana zero modes in an isolated one-dimensional superconductor
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Unconventional periodicities of the Little-Parks effect observed in a topological superconductor
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Fractional AC Josephson effect in a topological insulator proximitized by a self-formed superconductor
A lateral Josephson junction in which the surface of a 3D topological insulator serves as the weak link should support topologically protected excitations related to Majorana fermions. The resulting 4π-periodic current-phase relationship could be detected under high-frequency excitation by the suppression of odd Shapiro steps. Here, in this study, we demonstrate such devices through the self-formation of a Pd-Te superconducting layer from a telluride topological insulator, and observe suppressed first and third Shapiro steps. Other devices, including those where the Pd-Te layer is bolstered by an additional Al layer, show no suppression of Shapiro steps, a difference supported by simulations. Though we rule out the known trivial causes of suppressed Shapiro steps in our devices, we nevertheless argue that corroborating measurements and disorder-aware theoretical descriptions of these systems are needed before confidently claiming the observation of Majorana states.
Superradiant emission stimulated by vortex-antivortex pair production in layered superconductors
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Controlled disorder-induced peak effect in the single-crystalline Ca 3 Rh 4 Sn 13 superconductor
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Probing the Berezinskii-Kosterlitz-Thouless vortex unbinding transition in two-dimensional superconductors using local noise magnetometry
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Symmetry-enforced Fermi surface degeneracies observed in the purported time-reversal symmetry-broken superconductor LaNiGa 2
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Search for orbital magnetism in the kagome superconductor CsV 3 Sb 5 using neutron diffraction
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Mirror-protected Majorana zero modes in f -wave multilayer graphene superconductors
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First order phase transition in a two-dimensional superconductor
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Widespread orthorhombic fluctuations in the (Sr, Na) Fe2 As2 family of superconductors
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Unmasking the Origin of Kinks in the Photoemission Spectra of Cuprate Superconductors
The origin of a ubiquitous bosonic coupling feature in the photoemission spectra of high- T c cuprates, an energy-momentum dispersion “kink” observed at ~70 meV binding energy, remains a two-decade-old mystery. Understanding this phenomenon requires an accurate description of the coupling between the electron and some collective modes. In this work, we report ab initio calculations based on G W perturbation theory and show that correlation-enhanced electron-phonon interaction in cuprates gives rise to the strong kinks, which not only explains quantitatively the observations but provides new understanding of experiments. Our results reveal it is the electron density of states being the predominant factor in determining the doping dependence of the kink size, manifesting the multiband nature of the cuprates, as opposed to the prevalent belief of it being a measure of the mode-coupling strength.
Ubiquitous Superconducting Diode Effect in Superconductor Thin Films
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Density of States and Spectral Function of a Superconductor out of a Quantum-Critical Metal
We analyze the validity of a quasiparticle description of a superconducting state above a metallic quantum-critical point (QCP). A normal state at a QCP is a non-Fermi liquid with no coherent quasiparticles. A superconducting order gaps out low-energy excitations, except for a sliver of states for non-s-wave gap symmetry, and at a first glance, restores coherent quasiparticle behavior. We argue that this does not necessarily hold as the fermionic self-energy may remain singular above the gap edge. This singularity gives rise to markedly non-BCS behavior of the density of states and to the appearance of a nondispersing mode at the gap edge in the spectral function. We analyze the set of quantum-critical models with an effective dynamical four-fermion interaction V(Ω) ∝ 1/Ω γ , where Ω is a frequency of a boson, which mediates the interaction. We show that coherent quasiparticle behavior in a superconducting state holds for γ < 1/2, but breaks down for larger γ. Here, we discuss signatures of quasiparticle breakdown and compare our results with the photoemission data for Bi2201 and Bi2212.