Publications by authors named "Finkelstein G"

We perform a systematic study of Andreev conversion at the interface between a superconductor and graphene in the quantum Hall (QH) regime. We find that the probability of Andreev conversion from electrons to holes follows an unexpected but clear trend: the dependencies on temperature and magnetic field are nearly decoupled. We discuss these trends and the role of the superconducting vortices, whose normal cores could both absorb and dephase the individual electrons in a QH edge.

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Article Synopsis
  • Superconducting diodes are innovative circuit elements that allow electrical current to flow without resistance in one direction while being resistive in the opposite direction.
  • Recent advancements have shown new types of these devices, but many have low efficiency and rely on magnetic fields; however, this study presents a device achieving nearly 100% efficiency at zero magnetic field.
  • The device, called a Josephson triode, consists of three graphene Josephson junctions and demonstrates its effectiveness by rectifying small electrical signals, suggesting potential applications in modern quantum circuits.
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Claude Bernard (1813-1878) and Emil du Bois-Reymond (1818-1896) rank as two of the most influential scientists of the nineteenth century. Renowned for their experiments, lectures, and writing, Bernard and du Bois-Reymond earned great prestige as professors of physiology in a time when Paris and Berlin reigned as capitals of science. Yet even though they were equals in every way, du Bois-Reymond's reputation has fallen far more than Bernard's.

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A two-dimensional, anisotropic superconductivity was recently found at the KTaO(111) interfaces. The nature of the anisotropic superconducting transition remains a subject of debate. To investigate the origins of the observed behavior, we grew epitaxial KTaO(111)-based heterostructures.

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The vanishing band gap of graphene has long presented challenges for making high-quality quantum point contacts (QPCs)─the partially transparent p-n interfaces introduced by conventional split gates tend to short circuit the QPCs. This complication has hindered the fabrication of graphene quantum Hall Fabry-Pérot interferometers, until recent advances have allowed split-gate QPCs to operate utilizing the highly resistive ν = 0 state. Here, we present a simple recipe to fabricate QPCs by etching a narrow trench in the graphene sheet to separate the conducting channel from self-aligned graphene side gates.

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The dynamical properties of multiterminal Josephson junctions (MT-JJs) have attracted interest, driven by the promise of new insights into synthetic topological phases of matter and Floquet states. This effort has culminated in the discovery of Cooper multiplets in which the splitting of a Cooper pair is enabled via a series of Andreev reflections that entangle four (or more) electrons. Here, we show that multiplet resonances can also emerge as a consequence of the three-terminal circuit model.

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We synthesized and characterized a novel iron(II) aceto EMIM coordination compound, which has a simplified empirical formula Fe(OAc)[EMIM], in two different hydration forms: as anhydrous monoclinic compound and triclinic dihydrate Fe(OAc)[EMIM]·2HO. The dihydrate compound is isostructural with recently reported Mn(OAc)[EMIM]·2HO, while the anhydrate is a superstructure of the Mn counterpart, suggesting the existence of solid solutions. Both new Fe compounds contain chains of Fe octahedrally coordinated exclusively by acetate groups.

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When a Josephson junction is exposed to microwave radiation, it undergoes the inverse AC Josephson effect─the phase of the junction locks to the drive frequency. As a result, the - curves of the junction acquire "Shapiro steps" of quantized voltage. If the junction has three or more superconducting contacts, coupling between different pairs of terminals must be taken into account and the state of the junction evolves in a phase space of higher dimensionality.

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The high-pressure phases of oxyhydroxides (δ-AlOOH, ε-FeOOH, and their solid solution), candidate components of subducted slabs, have wide stability fields, thus potentially influencing volatile circulation and dynamics in the Earth's lower mantle. Here, we report the elastic wave velocities of δ-(Al,Fe)OOH (Fe/(Al + Fe) = 0.13, δ-Fe13) to 79 GPa, determined by nuclear resonant inelastic X-ray scattering.

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The AC Josephson effect manifests itself in the form of "Shapiro steps" of quantized voltage in Josephson junctions subject to radiofrequency (RF) radiation. This effect presents an early example of a driven-dissipative quantum phenomenon and is presently utilized in primary voltage standards. Shapiro steps have also become one of the standard tools to probe junctions made in a variety of novel materials.

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We synthesized and determined crystal structures of two manganese(II) aceto EMIM coordination compounds with simplified empirical formulas Mn(OAc)[EMIM] and Mn(OAc)[EMIM]·2HO. Both compounds feature extended chains of Mn octahedrally coordinated exclusively by acetate anions, which has been observed for the first time. The EMIM moieties and water molecules participate in hydrogen bonding with acetate anions but do not directly interact with the metal cation.

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Background: Mobile elements comprise a large fraction of metazoan genomes. Accumulation of mobile elements is bound to produce multiple putative double-stranded RNA (dsRNA) structures within the transcriptome. These endogenous dsRNA structures resemble viral RNA and may trigger false activation of the innate immune response, leading to severe damage to the host cell.

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We present a study of a graphene-based Josephson junction with dedicated side gates carved from the same sheet of graphene as the junction itself. These side gates are highly efficient and allow us to modulate carrier density along either edge of the junction in a wide range. In particular, in magnetic fields in the 1- to 2-T range, we are able to populate the next Landau level, resulting in Hall plateaus with conductance that differs from the bulk filling factor.

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In situ high pressure single crystal X-ray diffraction study reveals that the quantum material CaMnBi undergoes a unique plane to chain structural transition between 2 and 3 GPa, accompanied by a large volume collapse. Puckered Mn-Mn honeycomb layer converts to quasi-one-dimensional (1D) zigzag chains above the phase transition pressure. Single crystal measurements reveal that the pressure-induced structural transformation is accompanied by a dramatic 2 orders of magnitude drop of resistivity.

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We present the combined results of single crystal X-ray diffraction, physical properties characterization, and theoretical assessment of EuSnP under high pressure. Single crystals of EuSnP prepared using Sn self-flux crystallize in the tetragonal NbCrN-type crystal structure (S.G.

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Ernst Haeckel and Emil du Bois-Reymond were the most prominent champions of Darwin in Germany. This essay compares their contributions to popularizing the theory of evolution, drawing special attention to the neglected figure of du Bois-Reymond as a spokesman for a world devoid of natural purpose. It suggests that the historiography of the German reception of Darwin's theory needs to be reassessed in the light of du Bois-Reymond's Lucretian outlook.

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We investigate the electronic properties of ballistic planar Josephson junctions with multiple superconducting terminals. Our devices consist of monolayer graphene encapsulated in boron nitride with molybdenum-rhenium contacts. Resistance measurements yield multiple resonant features, which are attributed to supercurrent flow among adjacent and nonadjacent Josephson junctions.

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We present a novel magnetic semiconductor, CrGaSe, synthesized by partially replacing magnetic Cr in antiferromagnetic CrSe with nonmagnetic Ga. The crystal structure of CrGaSe was determined by both powder and single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic structure with space group C2/ m (No.

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Single crystals of a complex Zintl compound with the composition NaGe were synthesized for the first time using a high-pressure/high-temperature approach. Single-crystal diffraction of synchrotron radiation revealed a hexagonal crystal structure with P6/m space group symmetry that is composed of a three-dimensional sp Ge framework punctuated by small and large channels along the crystallographic c axis. Na atoms are inside hexagonal prism-based Ge cages along the small channels, while the larger channels are occupied by layers of disordered sixfold Na rings, which are in turn filled by disordered [Ge] tetrahedra.

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We investigate the critical current I_{C} of ballistic Josephson junctions made of encapsulated graphene-boron-nitride heterostructures. We observe a crossover from the short to the long junction regimes as the length of the device increases. In long ballistic junctions, I_{C} is found to scale as ∝exp(-k_{B}T/δE).

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We present transport measurements on long, diffusive, graphene-based Josephson junctions. Several junctions are made on a single-domain crystal of CVD graphene and feature the same contact width of ∼9 μm but vary in length from 400 to 1000 nm. As the carrier density is tuned with the gate voltage, the critical current in these junctions ranges from a few nanoamperes up to more than 5 μA, while the Thouless energy, ETh, covers almost 2 orders of magnitude.

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A promising route for creating topological states and excitations is to combine superconductivity and the quantum Hall (QH) effect. Despite this potential, signatures of superconductivity in the QH regime remain scarce, and a superconducting current through a QH weak link has been challenging to observe. We demonstrate the existence of a distinct supercurrent mechanism in encapsulated graphene samples contacted by superconducting electrodes, in magnetic fields as high as 2 tesla.

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The nonoxidizing catalytic noble metal rhodium is introduced for ultraviolet plasmonics. Planar tripods of 8 nm Rh nanoparticles, synthesized by a modified polyol reduction method, have a calculated local surface plasmon resonance near 330 nm. By attaching p-aminothiophenol, local field-enhanced Raman spectra and accelerated photodamage were observed under near-resonant ultraviolet illumination, while charge transfer simultaneously increased fluorescence for up to 13 min.

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