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Abstract A quantum critical point (QCP) is currently being conjectured for the BaFe2(As1−x P x )2 system at the critical value x c ≈ 0.3. In the proximity of a QCP, all thermodynamic and transport properties are expected to scale with a single characteristic energy, given by the quantum fluctuations. Such a universal behavior has not, however, been found in the superconducting upper critical field H c2. Here we report H c2 data for epitaxial thin films extracted from the electrical resistance measured in very high magnetic fields up to 67 Tesla. Using a multi-band analysis we find that H c2 is sensitive to the QCP, implying a significant charge carrier effective mass enhancement at the doping-induced QCP that is essentially band-dependent. Our results point to two qualitatively different groups of electrons in BaFe2(As1−x P x )2. The first one (possibly associated to hot spots or whole Fermi sheets) has a strong mass enhancement at the QCP, and the second one is insensitive to the QCP. The observed duality could also be present in many other quantum critical systems.

We studied the impact of soft ferromagnetic permalloy (Py) on the shielding currents in a strong-pinning superconductor—YBa _2 Cu _3 O _7− _δ with Ba _2 Y(Nb/Ta)O _6 nano-precipitates—by means of scanning transmission x-ray microscopy. Typically and in particular when in the thin film limit, superconductor/ferromagnet (SC/FM) bilayers exhibit isotropic properties of the flux line ensemble at all temperatures. However, in elements with small aspect ratio a significant anisotropy in flux penetration is observed. We explain this effect by local in-plane fields arising from anisotropic magnetic stray fields originated by the ferromagnet. This leads to direction-dependent motion of magnetic vortices inside the SC/FM bilayer. Our results demonstrate that small variations of the magnetic properties can have huge impact on the superconductor.

Thin films of Fe-based superconductors (FBS) have been utilized in a plethora of different experiments for a fundamental understanding of the superconductivity in these materials, as well as for understanding and improving the materials with regard to possible applications. The developments and progress in thin film growth of these materials in the past 10 years are reviewed with a focus on the two main deposition techniques used so far for FBS (pulsed laser deposition, and molecular beam epitaxy). Possible choices of substrates or buffer systems are motivated and explained with regard to misfit, thermal expansion, chemical stability, etc. In the second part of this review, investigations on tuning the superconducting properties, especially critical temperature Tc and critical current density Jc, in FBS thin films are reviewed. [ABSTRACT FROM AUTHOR]

We investigate the field, angle and temperature dependence of the full-width critical current, Ic, of pulsed laser deposition-grown GdBa2Cu3O7 coated conductors with and without additional 6 mol% BaSnO3 (BSO) nanoparticles fabricated by SuperOx. The transport characteristics measured from 7 to 77 K and in applied magnetic fields of up to 6 T are complemented by scanning transmission electron microscopy. This combined approach allows for further insight into the vortex pinning mechanism and helps with understanding the enhancement in Ic. An exemplary scaling of the pinning force curves versus field at different temperatures confirms the additional contribution to pinning by the BSO nanoparticles. Through the temperature dependence of Ic, the weak and strong pinning contributions are determined: strong pinning dominates over almost the entire temperature range especially near the matching field of 1 T, where the largest enhancement in Ic is achieved. [ABSTRACT FROM AUTHOR]

The effects of granularity on the angle and field dependence of the transport Jc in coated conductors (CCs) are discussed. The granularity is revealed by scanning Hall probe microscopy of the trapped field profiles in tapes with different architectures. It was found that pulsed laser deposited (PLD) YBCO film on a RABiTS NiW substrate has the most prominent granular morphology in its trapped field profiles. This is complemented by a peculiar behavior of the critical currents when the orientation of the applied field is within a certain angular range around the ab-planes: Jc(θ) becomes independent of the angle and Jc(B) exhibits a peak. These phenomena are explained by the physics of Abrikosov–Josephson vortices at grain boundaries (GB) that leads to a transition from a GB-limited to a grain-limited regime both in Jc(θ) and Jc(B). The effects of granularity are strongly suppressed by the chemical solution deposition route for growing YBCO films on NiW, and are almost absent in PLD-YBCO on ABAD-textured templates. These results identify the collective influence of the GB on the percolative current flow in CCs, which becomes most significant at low temperatures. [ABSTRACT FROM AUTHOR]

The critical current density in thin films, which limits their application in external magnetic fields, can be enhanced by the introduction of artificial pinning centers such as non-superconducting nanoparticles inducing additional defects and local strain in the superconducting matrix. To understand the correlation between superconductivity, defect structures and particles, a controlled integration of particles with adjustable properties is essential. A powerful technique for the growth of isolated nanoparticles in the range of 10 nm is dc-magnetron sputtering in an inert gas flow. The inert gas condensation (IGC) of particles allows for an independent control of both the particle diameter distribution and the areal density. We report on the integration of such gas-phase-condensed nanoparticles into pulsed laser deposited (PLD) thin film multilayers with a combined PLD-IGC system. The particles and the structure of the multilayers are analyzed by transmission electron microscopy on cross-sectional FIB lamellae. As a result of the IGC particle implementation, randomly as well as biaxially oriented precipitates are formed in the thin films. With as few as three interlayers of nanoparticles, the pinning force density is enhanced in the low-field region. [ABSTRACT FROM AUTHOR]

Chemical solution deposition (CSD) is a promising way to realize REBa2Cu3O7−x (REBCO; RE = rare earth (here Y, Gd))-coated conductors with high performance in applied magnetic fields. However, the preparation process contains numerous parameters which need to be tuned to achieve high-quality films. Therefore, we investigated the growth of REBCO thin films containing nanometre-scale BaHfO3 (BHO) particles as pinning centres for magnetic flux lines, with emphasis on the influence of crystallization temperature and substrate on the microstructure and superconductivity. Conductivity, microscopy and x-ray investigations show an enhanced performance of BHO nano-composites in comparison to pristine REBCO. Further, those measurements reveal the superiority of GdBCO to YBCO—e.g. by inductive critical current densities, Jc, at self-field and 77 K. YBCO is outperformed by more than 1 MA cm−2 with Jc values of up to 5.0 MA cm−2 for 265 nm thick layers of GdBCO(BHO) on lanthanum aluminate. Transport in-field Jc measurements demonstrate high pinning force maxima of around 4 GN m−3 for YBCO(BHO) and GdBCO(BHO). However, the irreversibility fields are appreciably higher for GdBCO. The critical temperature was not significantly reduced upon BHO addition to both YBCO and GdBCO, indicating a low tendency for Hf diffusion into the REBCO matrix. Angular-dependent Jc measurements show a reduction of the anisotropy in the same order of magnitude for both REBCO compounds. Theoretical models suggest that more than one sort of pinning centre is active in all CSD films. [ABSTRACT FROM AUTHOR]

Wurzeln und Stengel von Phragmites communis aus Brackwasser-Sedimenten, die etwa 6 km nördlich Wangerooge in 23,1 bis 24,4 m unter NN erbohrt wurden, brachten 14C-Alter zwischen 7500 und 8000 v.h. Danach lag der Hochwasserspiegel der Nordsee in diesem Zeitraum etwa 24 m unter NN. Datierungen von in Lebendstellung entnommenen Muschelklappen von Scrobicularia plana ergeben für die Zeit um 1500 v.h. eine Hochwassermarke von ca. 1,3 m unter der heutigen. Für die Zeit um 550 v.h. kann mit Hilfe von Gräsern und Wurzeln eines ehemaligen Strandnelkenrasens sowie von Sedimentstrukturen einer Watt- bis Grodensedimentabfolge ein MTHW an der deutschen Nordseeküste angegeben werden, das dem heutigen entspricht.

Iron-based 1111-type superconductors display high critical temperatures and relatively high critical current densities J c . The typical approach to increasing J c is to introduce defects to control dissipative vortex motion. However, when optimized, this approach is theoretically predicted to be limited to achieving a maximum J c of only ∼30% of the depairing current density J d , which depends on the coherence length and the penetration depth. Here we dramatically boost J c in SmFeAsO 1-x H x films using a thermodynamic approach aimed at increasing J d and incorporating vortex pinning centres. Specifically, we reduce the penetration depth, coherence length and critical field anisotropy by increasing the carrier density through high electron doping using H substitution. Remarkably, the quadrupled J d reaches 415 MA cm -2 , a value comparable to cuprates. Finally, by introducing defects using proton irradiation, we obtain high J c values in fields up to 25 T. We apply this method to other iron-based superconductors and achieve a similar enhancement of current densities., (© 2024. The Author(s).)

The small G-protein CDC42 is an evolutionary conserved polarity protein and a key regulator of polarized cell functions, including directed cell migration. In vertebrates, alternative splicing gives rise to two CDC42 proteins: the ubiquitously expressed isoform (CDC42u) and the brain isoform (CDC42b), which only differ in their carboxy-terminal sequence, including the CAAX motif essential for their association with membranes. We show that these divergent sequences do not directly affect the range of CDC42's potential binding partners but indirectly influence CDC42-driven signaling by controlling the subcellular localization of the two isoforms. In astrocytes and neural precursors, which naturally express both variants, CDC42u associates with the leading-edge plasma membrane of migrating cells, where it recruits the Par6-PKCζ complex to fulfill its polarity function. In contrast, CDC42b mainly localizes to intracellular membrane compartments, where it regulates N-WASP-mediated endocytosis. Both CDC42 isoforms contribute their specific functions to promote the chemotaxis of neural precursors, demonstrating that their expression pattern is decisive for tissue-specific cell behavior., (© 2024 Ravichandran et al.)

High-entropy oxide (HEO) superconductors have been developed since very recently. Different superconductors can be produced in the form of a high-entropy compound, including REBa 2 Cu 3 O 7- δ (REBCO). However, until now, mainly bulk samples (mostly in polycrystalline form) have been reported. In this work, the first CSD-grown high-entropy (HE) REBCO nanocomposite films were successfully synthesized. In particular, high-quality Gd 0.2 Dy 0.2 Y 0.2 Ho 0.2 Er 0.2 Ba 2 Cu 3 O 7- δ nanocomposite films with 12 mol% BaHfO 3 nanoparticles were grown on SrTiO 3 substrates. The X-ray diffraction patterns show a near-perfect c -axis oriented grain growth. Both T c and 77 K J sf c , 91.9 K and 3.5 MA cm -2 , respectively, are comparable with the values of the single-RE REBCO films. Moreover, at low temperatures, specifically at 30 K, the J c values are larger than those of the single-RE samples. A transmission electron microscopy (TEM) study, including energy-dispersive X-ray spectroscopy (EDXS) measurements, reveals that the different RE 3+ ions are distributed homogeneously in the matrix without forming clusters. This distribution causes point-like pinning centres that explain the superior performances of these samples at low temperatures. Although still seen as a proof-of-concept for the feasibility of preparing such films, these results demonstrate that the HE REBCO films are a promising option for the future fabrication of high-performance coated conductors. In the investigated B - T range, however, their J c values are still lower than those of other, medium-entropy REBCO films, which shows that an optimization of the composition of the HE REBCO films is needed to maximize their performance., Competing Interests: The authors declare no competing interests., (This journal is © The Royal Society of Chemistry.)

The recent realisations of hydrogen doped LnFeAsO (Ln = Nd and Sm) superconducting epitaxial thin films call for further investigation of their structural and electrical transport properties. Here, we report on the microstructure of a NdFeAs(O,H) epitaxial thin film and its temperature, field, and orientation dependencies of the resistivity and the critical current density J c . The superconducting transition temperature T c is comparable to NdFeAs(O,F). Transmission electron microscopy investigation supported that hydrogen is homogenously substituted for oxygen. A high self-field J c of over 10 MA/cm 2 was recorded at 5 K, which is likely to be caused by a short London penetration depth. The anisotropic Ginzburg-Landau scaling for the angle dependence of J c yielded temperature-dependent scaling parameters γ J that decreased from 1.6 at 30 K to 1.3 at 5 K. This is opposite to the behaviour of NdFeAs(O,F). Additionally, γ J of NdFeAs(O,H) is smaller than that of NdFeAs(O,F). Our results indicate that heavily electron doping by means of hydrogen substitution for oxygen in LnFeAsO is highly beneficial for achieving high J c with low anisotropy without compromising T c , which is favourable for high-field magnet applications.

A low-cost chemical solution deposition technique was employed to prepare YBa 2 Cu 3 O 7-δ (YBCO) nanocomposite films starting from a colloidal solution containing preformed ZrO 2 nanocrystals. As previous publications revealed, an increase in the amount of nanocrystals results in a progressive deterioration of the film properties. The parameters that control this process and their interplay are still unknown in detail. Using definitive screening design (DSD), a design-of-experiments approach, allowed determining which of the multiple growth parameters play a key role for improving the superconducting properties of YBCO nanocomposite films even with a large concentration of nanocrystals. In order to show the potential of DSD, it has been applied for the optimization of two different properties: the critical temperature T c and the full width at half-maximum of the (005) YBCO reflection. This work shows that DSD is a powerful and efficient method that allows optimizing certain processes with a minimal number of experiments.

The main objective of this work was to study the superconducting properties of RE BCO films with a mixture of rare-earth ( RE ) ions with large difference in ion size, in particular Sm 3+ and Yb 3+ . These Yb 1- x Sm x Ba 2 Cu 3 O 7- δ films have been successfully prepared for the first time by chemical solution deposition following the extremely low-fluorine route, which allows reducing the fluorine content by 93% with respect to standard full trifluoroacetate solutions. On the one hand, critical temperature T c remains stable at approximately 90 K with Sm content up to x = 0.5 where T c starts to increase towards the values of pure SmBCO films of approximately 95 K. On the other hand, the critical current densities J c of the pure SmBCO films are the largest at 77 K, where the influence of a higher T c is very relevant, while at lower temperatures and low fields, the mixed films reach larger values. This demonstrates that mixing rare-earth elements RE in RE Ba 2 Cu 3 O 7- δ causes a change in the pinning properties of the films and reveals the importance of selecting adequate RE BCO compounds according to the temperature and magnetic field region of a desired application., Competing Interests: We declare we have no competing interests., (© 2020 The Authors.)

REBa 2 Cu 3 O 7-δ (REBCO, RE: rare earth, such as Y and Gd) compounds have been extensively studied as a superconducting layer in coated conductors. Although ErBCO potentially has better superconducting properties than YBCO and GdBCO, little research has been made on it, especially in chemical solution deposition (CSD). In this work, ErBCO films were deposited on IBAD (ion-beam-assisted-deposition) substrates by CSD with low-fluorine solutions. The crystallization process was optimized to achieve the highest self-field critical current density (J c ) at 77 K. Commonly, for the investigation of a CSD process involving numerous process factors, one factor is changed keeping the others constant, requiring much time and cost. For more efficient investigation, this study adopted a novel design-of-experiment technique, definitive screening design (DSD), for the first time in CSD process. Two different types of solutions containing Er-propionate or Er-acetate were used to make two types of samples, Er-P and Er-A, respectively. Within the investigated range, we found that crystallization temperature, dew point, and oxygen partial pressure play a key role in Er-P, while the former two factors are significant for Er-A. DSD revealed these significant factors among six process factors with only 14 trials. Moreover, the DSD approach allowed us to create models that predict J c accurately. These models revealed the optimum conditions giving the highest J c values of 3.6 MA/cm 2 for Er-P and 3.0 MA/cm 2 for Er-A. These results indicate that DSD is an attractive approach to optimize CSD process.

For the first time, GdBa 2 Cu 3 O 7-x nanocomposites were prepared by chemical solution deposition following the ex-situ approach. In particular, ~ 220 nm GdBa 2 Cu 3 O 7-x -HfO 2 (GdBCO-HfO 2 ) nanocomposite films were fabricated starting from a colloidal solution of 5 mol% HfO 2 nanoparticles. Hereby, one of the main challenges is to avoid the accumulation of the nanoparticles at the substrate interface during the pyrolysis, which would later prevent the epitaxial nucleation of the GdBCO grains. Therefore, the effect of pyrolysis processing parameters such as heating ramp and temperature on the homogeneity of the nanoparticle distribution has been investigated. By increasing the heating ramp to 300 °C/h and decreasing the final temperature to 300 °C, a more homogenous nanoparticle distribution was achieved. This translates into improved superconducting properties of the grown films reaching critical temperatures (T c ) of 94.5 K and self-field critical current densities ([Formula: see text]) at 77 K of 2.1 MA/cm 2 with respect to films pyrolyzed at higher temperatures or lower heating ramps.

Chemical solution deposition (CSD) was used to grow Y 1-x Gd x Ba 2 Cu 3 O 7-δ -BaHfO 3 (YGBCO-BHO) nanocomposite films containing 12 mol% BHO nanoparticles and various amounts of Gd, x , on two kinds of buffered metallic tapes: Ni5W and IBAD. The influence of the rare-earth stoichiometry on structure, morphology and superconducting properties of these films was studied. The growth process was carefully studied in order to find the most appropriate growth conditions for each composition and substrate. This led to a clear improvement in film quality, probably due to the reduction of BaCeO 3 formation. In general, the superconducting properties of the films on Ni5W are significantly better. For x > 0.5, epitaxial ~270 nm thick YGBCO-BHO films with T c > 93 K and self-field J c at 77 K ~2 MA/cm² were obtained on Ni5W. These results highlight the potential of this approach for the fabrication of high-quality coated conductors., Competing Interests: The authors declare no conflict of interest.

Usually hydroxyl groups present on top of oxidized silicon served as binding centers for a silanization reaction toward surface functionalization. In this study, we developed a novel surface functionalization strategy where hydroxyl functionalization on nonoxidized silicon surfaces are obtained. These surfaces were stable for several weeks even in ambient air at room temperature. This high stability indicates a strong spatial isolation of the hydroxyl groups because they keenly tend to undergo a condensation reaction, forming silicon oxide. To prove the applicability of the obtained hydroxylated silicon surface, we further modified the hydroxyl groups with a commonly used silane molecule, (3-aminopropyl)triethoxysilane (APTES). The functional amino groups of the APTES layer bonded to the surface were subsequently altered by N -maleoyl-β-alanin to generate a surface highly specific for the immobilization of thiol-containing biomolecules (like thiolated single-stranded DNA or cysteine-tagged proteins). All modification steps have been investigated by IR spectroscopic ellipsometry measurements.

Fe-based superconductors present a large variety of compounds whose physical properties strongly depend on the crystal structure and chemical composition. Among them, the so-called 1111 compounds show the highest critical temperature T c in the bulk form. Here we demonstrate the realization of excellent superconducting properties in NdFeAs(O 1- x F x ). We systematically investigated the correlation between the microstructure at the nanoscale and superconductivity in an epitaxial 22 nm NdFeAs(O 1- x F x ) thin film on a MgO single crystalline substrate ( T c = 44.7 K). Atomic resolution analysis of the microstructure by transmission electron microscopy and atom probe tomography identified several defects and other inhomogeneities at the nanoscale that can act as extrinsic pinning centers. X-Ray diffraction and transmission electron microscopy displayed a broad variation of the a -axis lattice parameter either due to a partially strained layer at the interface to the substrate, high local strain at dislocation arrays, mosaicity, or due to composition variation within the film. The electrical transport properties are substantially affected by intrinsic pinning and a matching field corresponding to the film thickness and associated with the Bean-Livingston surface barrier of the surfaces. The thin film showed a self-field critical current density J c (4.2 K) of ∼7.6 MA cm -2 and a record pinning force density of F p ≈ 1 TN m -3 near 35 T for H ‖ ab at 4.2 K. These investigations highlight the role of the microstructure in fine-tuning and possibly functionalizing the superconductivity of Fe-based superconductors., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A new state-of-the-art electrical transport measurement system was developed for the characterization of industrially produced coated conductors (CCs). The current leads are rated to a conduct current of up to 1000 A, which opens up the possibility of measuring the critical current I c of tapes at a wide range of temperatures. The setup operates in a He-gas flow cryostat that provides stable temperatures between 1.8 and 200 K. The setup is equipped with a split-coil magnet that can apply fields of up to 6 T. A continuous rotation of the sample with respect to the magnetic field with an angular resolution of 0.5° enables characterization of anisotropic I c of different tapes. In the measured voltage-current curves, weak sample heating mostly occurs from the dissipation in the tape during the I c transition. It is demonstrated that the system can provide reliable data on the properties of CCs at temperatures lower than 77 K for a magnet design and other applications. The results allow the study of vortex pinning for further prospects of engineering the microstructure of the superconducting layer as well as to assess the performance of various tapes with different architectures to achieve optimum performance at different operating temperatures and magnetic fields.

Y 1- x Gd x Ba 2 Cu 3 O 7- δ -BaHfO 3 (YGBCO-BHO) nanocomposite films containing 12 mol% BHO nanoparticles and different amounts of Gd were prepared by chemical solution deposition following the trifluoroacetic route on SrTiO 3 single crystals in order to study the influence of the rare earth stoichiometry on structure, morphology and superconducting properties of these films. We optimized the growth process for each of several Gd contents of the 220 nm thick YGBCO-BHO films by varying crystallization temperature and oxygen partial pressure. This optimization process led to the conclusion that mixing the rare earths in YGBCO-BHO films leads to wider growth parameter windows compared to YBCO-BHO and GdBCO-BHO films giving larger freedom for selecting the most convenient processing parameters in order to adapt to different substrates or applications which is very important for the industrial production of coated conductors. The optimized films show a continuous increase of T c with Gd content x from ∼90 K for the YBCO-BHO films to ∼94 K for the GdBCO-BHO films. Consequently, an increase of the 77 K self-field J c with Gd content is observed reaching values > 7 MA cm -2 for Gd contents x > 0.5. The transport properties of these films under applied magnetic fields are significantly improved with respect to the pristine YBCO films. All YGBCO-BHO nanocomposite films grew epitaxially with c -axis orientation and excellent out-of-plane and in-plane texture. The films are dense with a low amount of pores and only superficial indentations., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

An outstanding current carrying performance (namely critical current density, Jc) over a broad temperature range of 10-77 K for magnetic fields up to 12 T is reported for films of YBa2Cu3O7-x with Ba2Y(Nb,Ta)O6 inclusion pinning centres (YBCO-BYNTO) and thicknesses in the range of 220-500 nm. Jc values of 10 MA cm-2 were measured at 30 K - 5 T and 10 K - 9 T with a corresponding maximum of the pinning force density at 10 K close to 1 TN m-3. The system is very flexible regarding properties and microstructure tuning, and the growth window for achieving a particular microstructure is wide, which is very important for industrial processing. Hence, the dependence of Jc on the magnetic field angle was readily controlled by fine tuning the pinning microstructure. Transmission electron microscopy (TEM) analysis highlighted that higher growth rates induce more splayed and denser BYNTO nanocolumns with a matching field as high as 5.2 T. Correspondingly, a strong peak at the B||c-axis is noticed when the density of vortices is lower than the nanocolumn density. YBCO-BYNTO is a very robust and reproducible composite system for high-current coated conductors over an extended range of magnetic fields and temperatures.

A quantum critical point (QCP) is currently being conjectured for the BaFe 2 (As 1-x P x ) 2 system at the critical value x c  ≈ 0.3. In the proximity of a QCP, all thermodynamic and transport properties are expected to scale with a single characteristic energy, given by the quantum fluctuations. Such a universal behavior has not, however, been found in the superconducting upper critical field H c2 . Here we report H c2  data for epitaxial thin films extracted from the electrical resistance measured in very high magnetic fields up to 67 Tesla. Using a multi-band analysis we find that H c2 is sensitive to the QCP, implying a significant charge carrier effective mass enhancement at the doping-induced QCP that is essentially band-dependent. Our results point to two qualitatively different groups of electrons in BaFe 2 (As 1-x P x ) 2 . The first one (possibly associated to hot spots or whole Fermi sheets) has a strong mass enhancement at the QCP, and the second one is insensitive to the QCP. The observed duality could also be present in many other quantum critical systems.

High temperature (high-T c ) superconductors like cuprates have superior critical current properties in magnetic fields over other superconductors. However, superconducting wires for high-field-magnet applications are still dominated by low-T c Nb 3 Sn due probably to cost and processing issues. The recent discovery of a second class of high-T c materials, Fe-based superconductors, may provide another option for high-field-magnet wires. In particular, AEFe 2 As 2 (AE: Alkali earth elements, AE-122) is one of the best candidates for high-field-magnet applications because of its high upper critical field, H c2 , moderate H c2 anisotropy, and intermediate T c . Here we report on in-field transport properties of P-doped BaFe 2 As 2 (Ba-122) thin films grown on technical substrates by pulsed laser deposition. The P-doped Ba-122 coated conductor exceeds a transport J c of 10 5  A/cm 2 at 15 T for main crystallographic directions of the applied field, which is favourable for practical applications. Our P-doped Ba-122 coated conductors show a superior in-field J c over MgB 2 and NbTi, and a comparable level to Nb 3 Sn above 20 T. By analysing the E - J curves for determining J c , a non-Ohmic linear differential signature is observed at low field due to flux flow along the grain boundaries. However, grain boundaries work as flux pinning centres as demonstrated by the pinning force analysis.

Fe-based superconductors (FBS) present a large variety of compounds whose properties are affected to different extents by their crystal structures. Amongst them, the REFeAs(O,F) (RE1111, RE being a rare-earth element) is the family with the highest critical temperature T c but also with a large anisotropy and Josephson vortices as demonstrated in the flux-flow regime in Sm1111 (T c  ∼ 55 K). Here we focus on the pinning properties of the lower-T c Nd1111 in the flux-creep regime. We demonstrate that for H//c critical current density J c at high temperatures is dominated by point-defect pinning centres, whereas at low temperatures surface pinning by planar defects parallel to the c-axis and vortex shearing prevail. When the field approaches the ab-planes, two different regimes are observed at low temperatures as a consequence of the transition between 3D Abrikosov and 2D Josephson vortices: one is determined by the formation of a vortex-staircase structure and one by lock-in of vortices parallel to the layers. This is the first study on FBS showing this behaviour in the full temperature, field, and angular range and demonstrating that, despite the lower T c and anisotropy of Nd1111 with respect to Sm1111, this compound is substantially affected by intrinsic pinning generating a strong ab-peak in J c .

The Hall effect is a powerful tool for investigating carrier type and density. For single-band materials, the Hall coefficient is traditionally expressed simply by , where e is the charge of the carrier, and n is the concentration. However, it is well known that in the critical region near a quantum phase transition, as it was demonstrated for cuprates and heavy fermions, the Hall coefficient exhibits strong temperature and doping dependencies, which can not be described by such a simple expression, and the interpretation of the Hall coefficient for Fe-based superconductors is also problematic. Here, we investigate thin films of Ba(Fe1-xCox)2As2 with compressive and tensile in-plane strain in a wide range of Co doping. Such in-plane strain changes the band structure of the compounds, resulting in various shifts of the whole phase diagram as a function of Co doping. We show that the resultant phase diagrams for different strain states can be mapped onto a single phase diagram with the Hall number. This universal plot is attributed to the critical fluctuations in multiband systems near the antiferromagnetic transition, which may suggest a direct link between magnetic and superconducting properties in the BaFe2As2 system.

The addition of mixed double perovskite Ba2Y(Nb/Ta)O6 (BYNTO) to YBa2Cu3O(7-δ) (YBCO) thin films leads to a large improvement of the in-field current carrying capability. For low deposition rates, BYNTO grows as well-oriented, densely distributed nanocolumns. We achieved a pinning force density of 25 GN/m(3) at 77 K at a matching field of 2.3 T, which is among the highest values reported for YBCO. The anisotropy of the critical current density shows a complex behavior whereby additional maxima are developed at field dependent angles. This is caused by a matching effect of the magnetic fields c-axis component. The exponent N of the current-voltage characteristics (inversely proportional to the creep rate S) allows the depinning mechanism to be determined. It changes from a double-kink excitation below the matching field to pinning-potential-determined creep above it.

In general, the critical current density, Jc, of type II superconductors and its anisotropy with respect to magnetic field orientation is determined by intrinsic and extrinsic properties. The Fe-based superconductors of the '122' family with their moderate electronic anisotropies and high yet accessible critical fields (Hc2 and Hirr) are a good model system to study this interplay. In this paper, we explore the vortex matter of optimally Co-doped BaFe2As2 thin films with extended planar and c-axis correlated defects. The temperature and angular dependence of the upper critical field is well explained by a two-band model in the clean limit. The dirty band scenario, however, cannot be ruled out completely. Above the irreversibility field, the flux motion is thermally activated, where the activation energy U0 is going to zero at the extrapolated zero-kelvin Hirr value. The anisotropy of the critical current density Jc is both influenced by the Hc2 anisotropy (and therefore by multi-band effects) as well as the extended planar and columnar defects present in the sample.

The assessment of quantification results of the alcohol abuse marker ethyl glucuronide (EtG) in hair in comparison to the cut-off values for the drinking behavior may be complicated by cosmetic hair bleaching. Thus, the impact of increasing exposure to hydrogen peroxide on the EtG content of hair was investigated. Simultaneously, the change of absorbance in the range of 1000-1100 cm(-1) indicative for the oxidation of cystine was investigated non-destructively by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) using pulverized portions of the respective hair samples. Hair samples treated with hydrogen peroxide consistently displayed a significantly increased absorbance at 1040 cm(-1) associated with the formation of cysteic acid. The EtG content decreased significantly if the hair was treated with alkaline hydrogen peroxide as during cosmetic bleaching. It could be shown that ATR-FTIR is capable of detecting an exposure to hydrogen peroxide when still no brightening was visible and already before the EtG content deteriorated significantly. Thus, hair samples suspected of having been exposed to oxidative treatment may be checked non-destructively by a readily available technique. This assay is also possible retrospectively after EtG extraction and using archived samples., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Junction-mediating and regulatory protein (JMY) was originally identified as a transcriptional co-factor in the p53-response to DNA damage. Aside from this nuclear function, recent years have uncovered an additional function of JMY, namely in cytoskeleton remodelling and actin assembly. The C-terminus of JMY comprises a canonical VCA-module, the sequence signature of Arp2/3 complex activators. Furthermore, tandem repeats of 3 WH2 (V, or more recently also W) domains render JMY capable of Arp2/3 independent actin assembly. The motility promoting cytoplasmic function of JMY is abrogated upon DNA-damage and nuclear translocation of JMY. To address the precise cellular function of JMY in cellular actin rearrangements, we have searched for potential new interaction partners by mass spectrometry. We identified several candidates and correlated their localization with the subcellular dynamics of JMY. JMY is localized to dynamic vesiculo-tubular structures throughout the cytoplasm, which are decorated with actin and Arp2/3 complex. Moreover, JMY partially colocalizes and interacts with VAP-A, which is involved in vesicle-based transport processes. Finally, overexpression of JMY results in Golgi dispersal by loss from the trans-site and affects VSV-G transport. These analyses, together with biochemical experiments, indicate that JMY drives vesicular trafficking in the trans-Golgi region and at ER-membrane contact sites (MCS), distinct from other Arp2/3 activators involved in vesicle transport processes such as the related WHAMM or WASH., (Copyright © 2014 The Authors. Published by Elsevier GmbH.. All rights reserved.)

The discovery of superconductivity with a transition temperature, Tc, up to 65 K in single-layer FeSe (bulk Tc=8 K) films grown on SrTiO3 substrates has attracted special attention to Fe-based thin films. The high Tc is a consequence of the combined effect of electron transfer from the oxygen-vacant substrate to the FeSe thin film and lattice tensile strain. Here we demonstrate the realization of superconductivity in the parent compound BaFe2As2 (no bulk Tc) just by tensile lattice strain without charge doping. We investigate the interplay between strain and superconductivity in epitaxial BaFe2As2 thin films on Fe-buffered MgAl2O4 single crystalline substrates. The strong interfacial bonding between Fe and the FeAs sublattice increases the Fe-Fe distance due to the lattice misfit, which leads to a suppression of the antiferromagnetic spin density wave and induces superconductivity with bulk Tc≈10 K. These results highlight the role of structural changes in controlling the phase diagram of Fe-based superconductors.

The recently discovered oxypnictide superconductor SmFeAs(O,F) is the most attractive material among the Fe-based superconductors due to its highest transition temperature of 56 K and potential for high-field performance. In order to exploit this new material for superconducting applications, the knowledge and understanding of its electro-magnetic properties are needed. Recent success in fabricating epitaxial SmFeAs(O,F) thin films opens a great opportunity to explore their transport properties. Here we report on a high critical current density of over 10(5) A/cm(2) at 45 T and 4.2 K for both main field orientations, feature favourable for high-field magnet applications. Additionally, by investigating the pinning properties, we observed a dimensional crossover between the superconducting coherence length and the FeAs interlayer distance at 30-40 K, indicative of a possible intrinsic Josephson junction in SmFeAs(O,F) at low temperatures that can be employed in electronics applications such as a terahertz radiation source and a superconducting Qubit.

S. typhimurium can infect host cells not only by the well-established "trigger"-mode of invasion, inducing the formation of prominent membrane ruffles e.g., as during macropinocytosis, but also independently of these processes. Recently, we have found that the novel, ruffling-independent entry mechanism usurps the host cell contraction machinery. This mode of entry involves formation of myosin II-rich stress fiber-like structures at invasion sites, likely through stimulation of a RhoA/Rho-kinase signaling pathway and mostly downstream of the Salmonella virulence factor SopB. Importantly, this pathway operates independently of Arp2/3 complex, a central regulator of the macropinocytic entry mode. Here, we will describe our current thinking of how the contraction-dependent uptake mechanism operates to promote Salmonella invasion, and which additional cellular or bacterial factors might get engaged in the process. Finally, we will speculate on the implications of these findings for invasion by other bacterial pathogens, and discuss their impact on the canonical trigger-vs.-zipper classification of entry mechanisms employed by distinct bacterial pathogens.

Salmonella stimulates host cell invasion using virulence effectors translocated by the pathogen's type-three secretion system (T3SS). These factors manipulate host signaling pathways, primarily driven by Rho family GTPases, which culminates in Arp2/3 complex-dependent activation of host actin nucleation to mediate the uptake of Salmonella into host cells. However, recent data argue for the existence of additional mechanisms that cooperate in T3SS-dependent Salmonella invasion. We identify a myosin II-mediated mechanism, operating independent of but complementary to the Arp2/3-dependent pathway, as contributing to Salmonella invasion into nonphagocytic cells. We also establish that the T3SS effector SopB constitutes an important regulator of this Rho/Rho kinase and myosin II-dependent invasion pathway. Thus, Salmonella enters nonphagocytic cells by manipulating the two core machineries of actin-based motility in the host: Arp2/3 complex-driven actin polymerization and actomyosin-mediated contractility., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Having succeeded in the fabrication of epitaxial superconducting LaFeAsO(1-x)F(x) thin films we performed an extensive study of electrical transport properties. In the face of multiband superconductivity we can demonstrate that an anisotropic Ginzburg-Landau scaling of the angular dependent critical current densities can be adopted, although being originally developed for single band superconductors. In contrast with single band superconductors the mass anisotropy of LaFeAsO(1-x)F(x) is temperature dependent. A very steep increase of the upper critical field and the irreversibility field can be observed at temperatures below 6 K, indicating that the band with the smaller gap is in the dirty limit. This temperature dependence can be theoretically described by two dominating bands responsible for superconductivity. A pinning force scaling provides insight into the prevalent pinning mechanism and can be specified in terms of the Kramer model., (© 2011 American Physical Society)

Arp2/3 complex mediates the nucleation of actin filaments in multiple subcellular processes, and is activated by nucleation-promoting factors (NPFs) from the Wiskott-Aldrich Syndrome family. In exciting new developments, this family has grown by three members: WASH, WHAMM and JMY, which extend the repertoire of dynamic membrane structures that are remodeled following Arp2/3 activation in vivo. These novel NPFs share an actin- and Arp2/3-interacting WCA module, and combine Arp2/3 activation with additional biochemical functions, including capping protein inhibition, microtubule engagement or Arp2/3-independent actin nucleation, none of which had been previously associated with canonical WCA-harboring proteins. Uncovering the physiological relevance of these unique activities will require concerted efforts from multiple disciplines, and is sure to impact our understanding of how the cytoskeleton controls so many dynamic subcellular events., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Rutile single crystals treated with ion-beam preferential etching (IBPE) are investigated with electrical transport and transmission electron microscopy. The initially insulating single crystals show the formation of an oxygen vacancy-rich, highly ordered, thin conducting layer, below a crystalline rutile TiO(2) surface layer. Carrier concentrations of 10(19) cm(-3) and very high mobilities of the order of 300 cm(2) V(-1) s(-1) are observed in the nanolayers. The observations indicate that rutile single crystals can be effectively transformed into controlled conducting material using IBPE for creating a new breakthrough in transparent conducting media.

Superconducting LaFeAsO1-xFx thin films were grown on single crystalline LaAlO3 substrates with critical temperatures (onset) up to 28 K. Resistive measurements in high magnetic fields up to 40 T reveal a paramagnetically limited upper critical field mu{0}H{c2}(0) around 77 T and a remarkable steep slope of -6.2 T K-1 near T{c}. From transport measurements we observed weak-link behavior in low magnetic fields and evidence for a broad reversible regime.

Type III secretion system-mediated injection of a cocktail of bacterial proteins drives actin rearrangements, frequently adopting the shape of prominent protuberances of ruffling membrane, and culminating in host cell invasion of Gram-negative pathogens like Salmonella typhimurium. Different Salmonella effectors are able to bind actin and activate Rho-family GTPases, which have previously been implicated in mediating actin-dependent Salmonella entry by interacting with N-WASP or WAVE-complex, well-established activators of the actin nucleation machine Arp2/3-complex. Using genetic deletion and RNA interference studies, we show here that neither individual nor collective removal of these Arp2/3- complex activators affected host cell invasion as efficiently as Arp2/3-complex knock-down, although the latter was also not essential. However, interference with WAVE-complex function abrogated Salmonella-induced membrane ruffling without significantly affecting entry efficiency, actin or Arp2/3-complex accumulation. In addition, scanning electron microscopy images captured entry events in the absence of prominent membrane ruffles. Finally, localization and RNA interference studies indicated a relevant function in Salmonella entry for the novel Arp2/3-complex regulator WASH. These data establish for the first time that Salmonella invasion is separable from bacteria-induced membrane ruffling, and uncover an additional Arp2/3-complex activator as well as an Arp2/3-complex-independent actin assembly activity that contribute to Salmonella invasion.