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Josephson junctions form the core circuit element in superconducting quantum computing circuits, single flux quantum digital logic circuits, and sensing devices such as SQUIDs. Aluminum oxide has typically been used as the tunnel barrier.…

We calculate the dc Josephson current $I_J$ for two types of superconductor-ferromagnet (S/F) Josephson junctions. The junction of the first type is a S/F/S junction. On the basis of the Eilenberger equation, the Josephson current is…

Superconductivity · Physics 2009-11-07 F. S. Bergeret , A. F. Volkov , K. B. Efetov

Operation of Josephson electronics usually requires determination of the Josephson critical current $I_c$, which is affected both by fluctuations and measurement noise. Lock-in measurements allow obviation of $1/f$ noise and, therefore,…

Superconductivity · Physics 2021-12-09 Razmik A. Hovhannisyan , Olena M. Kapran , Taras Golod , Vladimir M. Krasnov

We report the first experimental observation of the two-node thickness dependence of the critical current in Josephson junctions with a ferromagnetic interlayer. Vanishings of the critical current correspond to transitions into pi-state and…

Superconductivity · Physics 2007-05-23 V. A. Oboznov , V. V. Bol'ginov , A. K. Feofanov , V. V. Ryazanov , A. I. Buzdin

The addition of artificial pinning centers has led to an impressive increase in critical current density ($J_{\rm c}$) in a superconductor, enabling record-breaking all-superconducting magnets and other applications. $J_{\rm c}$ has reached…

We calculate a nondissipative spin current and show that it can flow with or without a charge current. We consider a two-band model which can be applied to the description of Fe-based pnictides in coexistence regime of superconductivity and…

Superconductivity · Physics 2015-01-30 Andreas Moor , Anatoly F. Volkov , Konstantin B. Efetov

We have probed the superconducting proximity effect through long high-quality monocrystalline Ag nanowires, by realizing Josephson junctions of different lengths, with different superconducting materials. Thanks to the high number of…

Mesoscale and Nanoscale Physics · Physics 2021-01-04 A. Murani , S. Sengupta , A. Kasumov , R. Deblock , Caroline Celle , J-P. Simonato , H. Bouchiat , S. Guéron

Critical current density (Jc) is one of the major limiting factors for high field applications of iron-based superconductors. Here, we report that Mn-ions are successfully incorporated into nontoxic superconducting (Li,Fe)OHFeSe films.…

Transport is called nonreciprocal when not only the sign, but also the absolute value of the current, depends on the polarity of the applied voltage. It requires simultaneously broken inversion and time-reversal symmetries, e.g., by the…

We study the Josephson current in long ballistic superconductor-monolayer graphene-superconductor junctions. As a first step, we have developed an efficient computational approach to calculate the Josephson current in tight-binding systems.…

Mesoscale and Nanoscale Physics · Physics 2016-06-15 Péter Rakyta , Andor Kormányos , József Cserti

We have studied Josephson junctions with barriers prepared from the Heusler compound Cu$_2$MnAl. In the as-prepared state the Cu$_2$MnAl layers are non ferromagnetic and the critical Josephson current density $j_{c}$ decreases exponentially…

Superconductivity · Physics 2010-03-11 D. Sprungmann , K. Westerholt , H. Zabel , M. Weides , H. Kohlstedt

We have observed the Josephson effect in junctions formed between single crystals of SrFe1.74Co0.26As2 and Ba0.23K0.77Fe2As2. I-V curves showed resistively-shunted junction characteristics, and the ac Josephson effect was observed under…

Josephson tunnel junctions are widely used as nonlinear elements in superconducting circuits such as low noise amplifiers and quantum bits. However, microscopic defects in the oxide tunnel barrier can produce low and high frequency noise…

Superconductivity · Physics 2010-06-10 R. Vijay , J. D. Sau , Marvin L. Cohen , I. Siddiqi

We propose, implement and test experimentally long Josephson 0-pi junctions fabricated using conventional Nb-AlOx-Nb technology. We show that using a pair of current injectors, one can create an arbitrary discontinuity of the Josephson…

Superconductivity · Physics 2007-05-23 E. Goldobin , A. Sterck , T. Gaber , D. Koelle , R. Kleiner

The $4\pi$ Josephson Effect is a distinguishing feature of a topological Josephson junction. However, stringent conditions make it hard to observe in experiments. Here we numerically study the transient transport properties in a topological…

Mesoscale and Nanoscale Physics · Physics 2018-02-07 Dihao Sun , Jie Liu

We investigate numerically a long Josephson junction with several phase pi-discontinuity points. Such junctions are usually fabricated as a ramp between an anisotropic cuprate superconductor like YBCO and an isotropic metal superconductor…

Superconductivity · Physics 2007-05-23 E. Goldobin , D. Koelle , R. Kleiner

Numerical modeling of dependences ``critical current -- external magnetic field'' for geometrically symmetric $0-\pi$ Josephson junctions is performed. The calculation of critical current is reduced to non-linear eigenvalue problem. The…

Superconductivity · Physics 2007-05-23 J. A. Angelova , T. L. Boyadjiev

In 2010, several experimental groups obtained compelling evidence for spin-triplet supercurrent in Josephson junctions containing strong ferromagnetic materials. Our own best results were obtained from large-area junctions containing a…

Superconductivity · Physics 2012-08-27 Yixing Wang , W P Pratt, , Norman O Birge

We report significant transport critical currents firstly achieved in Sr0.6K0.4Fe2As2 wires and tapes with a Tc = 34 K, which were fabricated through an in-situ powder-in-tube process. Silver was used as a chemical addition as well as a…

We study the critical depinning current Jc versus the applied magnetic flux Phi, for quasiperiodic (QP) chains and 2D arrays of pinning centers placed on the nodes of a five-fold Penrose lattice. In QP chains, the peaks in Jc(Phi) are…

Superconductivity · Physics 2021-03-16 V. R. Misko , Sergey Savel'ev , Franco Nori