Bicrystalline Grain Boundary and Hybrid SNS Junctions Based on Ba-122 Thin Films

Schmidt, S.; Döring, Sebastian; Schmidl, F.; Tympel, Volker; Haindl, S.; Iida, K.; Kurth, F.; Holzäpfel, B.; Seidel, P.

doi:10.1109/tasc.2012.2226861

Cited by 18 publications

(12 citation statements)

References 11 publications

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“…A large excess current of 645 mA lowers the formal I c from 950 mA to an effective value of 305 mA (see Fig. 15) which decreases the I c R N value of 20.2 mV to a corrected value of I c Ã R N ¼ 6.5 mV [50]. The critical current density across the microbridge is up to 1.4 10 5 A cm À2 (formal value), which is also reduced to 1.2 10 4 A cm À2 (corrected value) when subtracting the influence of the excess current.…”

Section: I-v Characteristics and Their Temperature Dependencementioning

confidence: 99%

Josephson effects at iron pnictide superconductors: Approaching phase‐sensitive experiments

Schmidt

Döring

Hasan

et al. 2016

Physica Status Solidi (b)

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The electrical transport in the pnictides especially the quasiparticle tunnelling and Josephson effects in inhomogeneous superconducting systems can provide information on the symmetry of the order parameter. Different kinds of Josephson junctions with one or two pnictide electrodes were realised and their properties were experimentally studied in detail (e.g., current–voltage characteristics, microwave response, current‐phase relations, dependencies on temperature and external magnetic field). These results were compared to well‐known Josephson junctions and recent theories taking into account the special properties (multiband superconductivity, exotic pairing symmetry) of the pnictides. By combination of two junctions in different crystal directions with different barrier transparencies one forms corner junctions or SQUIDs as phase‐sensitive devices. If the technological problems can be solved the investigations on such devices will finally clear up the symmetry of the pnictides, directly. These investigations will lead to a better understanding of fundamental properties of the pnictides as well as to a realistic judgement on the potential for applications of pnictides in superconducting electronics and sensor applications, both established ones and novel ones utilising the special pnictide properties.

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Section: I-v Characteristics and Their Temperature Dependencementioning

confidence: 99%

Josephson effects at iron pnictide superconductors: Approaching phase‐sensitive experiments

Schmidt

Döring

Hasan

et al. 2016

Physica Status Solidi (b)

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“…In our investigations on iron pnictide superconductors we prepared planar Josephson junctions using a sputtered insulating layer as barrier. Up to now different works for Josephson junctions with single crystals, [1][2][3] for bi-crystal grain boundary junctions [4][5][6][7][8] and edge-type junctions 9,10 as well as for planar junctions 11 were published. The Josephson junctions presented therein used natural or engineered interfaces as well as normal metal layers as barrier, but up to now, no work with a deposited insulating barrier has been published.…”

Section: Introductionmentioning

confidence: 99%

Investigation of TiOx barriers for their use in hybrid Josephson and tunneling junctions based on pnictide thin films

Döring

Monecke

Schmidt

et al. 2014

Journal of Applied Physics

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We tested oxidized titanium layers as barriers for hybrid Josephson junctions with high I c R n -products and for the preparation of junctions for tunneling spectroscopy. For that we firstly prepared junctions with conventional superconductor electrodes lead and niobium, respectively. By tuning the barrier thickness we were able to change the junctions' behavior from a Josephson junction to tunnel-like behavior applicable for quasi-particle spectroscopy. Subsequently, we transferred the technology to junctions using Co-doped BaFe 2 As 2 thin films prepared by pulsed laser deposition as base electrode and evaporated Pb as counter electrode. For barriers with a thickness of 1.5 nm we observe clear Josephson effects with I c R n ≈ 90 µV at 4.2 K. These junctions behave SNS'-like and are dominated by Andreev reflection transport mechanism. For junctions with barrier thickness of 2.0 nm and higher no Josephson but SIS'-or SINS'-like behavior with a tunnel-like conductance spectrum was observed.

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“…The symmetry of the superconducting order parameter has been investigated by means of hybrid Josephson junctions using Codoped Ba-122 thin films realizing S'NS-type Josephson junctions as well as SQUID using bicrystal junctions. [2][3][4][5] Many groups have prepared thin films of the so called "122" family with AE Fe 2 As 2 (AE : alkali earth elements, Sr and Ba) by means of pulsed laser deposition (PLD) and molecular beam epitaxy (MBE). [6][7][8][9][10][11][12][13] We have proposed the usage of Fe as a buffer layer on a MgO (001) substrate for growing Co-doped Ba-122 thin films, which yields high crystalline quality as well as improved superconducting properties under our deposition conditions.…”

mentioning

confidence: 99%

Versatile fluoride substrates for Fe-based superconducting thin films

Kurth

Reich

Hänisch

et al. 2013

Applied Physics Letters

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We demonstrate the growth of Co-doped BaFe2As2 (Ba-122) thin films on AEF2 (001) (AE: Ca, Sr, Ba) single crystal substrates using pulsed laser deposition. All films are grown epitaxially despite of a large misfit of -10.6% for BaF2 substrate. For all films a reaction layer is formed at the interface confirmed by X-ray diffraction and by transmission electron microscopy. The superconducting transition temperature of the film on CaF2 is around 27 K, whereas the corresponding values of the other films are around 21 K. The Ba-122 on CaF2 shows identical crystalline quality and superconducting properties as films on Fe-buffered MgO.Comment: 5 pages, 6 figures, 2 table

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Bicrystalline Grain Boundary and Hybrid SNS Junctions Based on Ba-122 Thin Films

Cited by 18 publications

References 11 publications

Josephson effects at iron pnictide superconductors: Approaching phase‐sensitive experiments

Josephson effects at iron pnictide superconductors: Approaching phase‐sensitive experiments

Investigation of TiOx barriers for their use in hybrid Josephson and tunneling junctions based on pnictide thin films

Versatile fluoride substrates for Fe-based superconducting thin films

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