Kondo effect and spin-active scattering in ferromagnet-superconductor junctions

We study the interplay of superconducting and ferromagnetic correlations on charge transport in different geometries with a focus on both a quantum point contact as well as a quantum dot in the even and the odd state with and without spin-active scattering at the interface. In order to obtain a complete picture of the charge transport we calculate the full counting statistics in all cases and compare the results with experimental data. We show that spin-active scattering is an essential ingredient in the description of quantum point contacts. This holds also for quantum dots in an even charge state whereas it is strongly suppressed in a typical Kondo situation. We explain this feature by the strong asymmetry of the hybridisations with the quantum dot and show how Kondo peak splitting in a magnetic field can be used for spin filtering. For the quantum dot in the even state spin-active scattering allows for an explanation of the experimentally observed mini-gap feature.Comment: 14 pages, 7 figures, accepted by PR

Magnetic field tuning and quantum interference in a Cooper pair splitter

Cooper pair splitting (CPS) is a process in which the electrons of naturally occurring spin-singlet pairs in a superconductor are spatially separated using two quantum dots. Here we investigate the evolution of the conductance correlations in an InAs CPS device in the presence of an external magnetic field. In our experiments the gate dependence of the signal that depends on both quantum dots continuously evolves from a slightly asymmetric Lorentzian to a strongly asymmetric Fano-type resonance with increasing field. These experiments can be understood in a simple three - site model, which shows that the nonlocal CPS leads to symmetric line shapes, while the local transport processes can exhibit an asymmetric shape due to quantum interference. These findings demonstrate that the electrons from a Cooper pair splitter can propagate coherently after their emission from the superconductor and how a magnetic field can be used to optimize the performance of a CPS device. In addition, the model calculations suggest that the estimate of the CPS efficiency in the experiments is a lower bound for the actual efficiency.Comment: 5 pages + 4 pages supplementary informatio

Pressure dependence of the spin gap in BaVS_3

We carried out magnetotransport experiments under hydrostatic pressure in order to study the nature of the metal-insulator transition in BaVS$_3$. Scaling relations for $\rho(T,H,p)$ are established and the pressure dependence of the spin gap is determined. Our new results, in conjunction with a re-analysis of earlier specific heat and susceptibility data, demonstrate that the transition is weakly second order. The nature of the phase diagram in the $T$--$p$--$H$ space is discussed.Comment: 5 pages, 5 figures, submitted to PRB Rap. Co

Tree-level (pi, K)-amplitude and analyticity

We consider the tree-level amplitude, describing all 3 channels of the binary (pi ,K)-reaction, as a meromorphic polynomially bounded function of 3 dependent complex variables. Relying systematically on the Mittag-Leffler theorem, we construct 3 convergent partial fraction expansions, each one being applied in the corresponding domain. Noting, that the mutual intersections of those domains are nonempty, we realize the analytical continuation. It is shown that the necessary conditions to make such a continuation feasible, are the following: 1) The only parameters completely determining the amplitude are the on-shell couplings and masses; 2) These parameters are restricted by a certain (infinite) system of bootstrap equations; 3) The full cross-symmetric amplitude takes the typically dual form, the Pomeron contribution being taken into account; 4)This latter contribution corresponds to a nonresonant background, which, in turn, is expressed in terms of cross-channel resonances parameters. It is demonstrated also, that the Chiral Symmetry provides a unique scale for the mentioned parameters, the resonance saturation effect appearing as a direct consequence of the above results

Electrically Controlled Spin Injection from Giant Rashba Spin-Orbit Conductor BiTeBr

Ferromagnetic materials are the widely used source of spin-polarized electrons in spintronic devices, which are controlled by external magnetic fields or spin-transfer torque methods. However, with increasing demand for smaller and faster spintronic components utilization of spin-orbit phenomena provides promising alternatives. New materials with unique spin textures are highly desirable since all-electric creation and control of spin polarization is expected where the strength, as well as an arbitrary orientation of the polarization, can be defined without the use of a magnetic field. In this work, we use a novel spin-orbit crystal BiTeBr for this purpose. Because of its giant Rashba spin splitting, bulk spin polarization is created at room temperature by an electric current. Integrating BiTeBr crystal into graphene-based spin valve devices, we demonstrate for the first time that it acts as a current-controlled spin injector, opening new avenues for future spintronic applications in integrated circuits

The European Legal Framework on Cybercrime

This article analyzes the European legal framework on cybercrime. Initially, it argues the challenges of cybercrime to traditional criminal justice systems. Subsequently, it focuses on the criminal law framework on cybercrime with a mainly European perspective. The European legal framework provides a three-path solution: the reduction of frictions among national legislations, the introduction of new investigative powers and the facilitation of international cooperation. The article presents and discusses each solution. Further, it argues that the effective implementation of the main legal instruments does not seem to depend on the legal enforceability of these international measures. Contrarily, other, non legal, factors such as national security, politics, the economy and the public opinion appear to stimulate the spontaneous implementation of the European legal framework. In this context, the added value of the EU action is rather low, although the Treaty of Lisbon and the Stockholm Programme may improve this situation in the long ter

Three dose levels of a maternal respiratory syncytial virus vaccine candidate are well tolerated and immunogenic in a randomized trial in non-pregnant women

BACKGROUND: Respiratory syncytial virus (RSV) causes respiratory tract infections, which may require hospitalization especially in early infancy. Transplacental transfer of RSV antibodies could confer protection to infants in their first months of life. METHODS: In this first-in-human, placebo-controlled study, 502 healthy non-pregnant women were randomized 1:1:1:1 to receive a single dose of unadjuvanted vaccine containing 30/60/120 µg of RSV fusion (F) protein stabilized in the prefusion conformation (RSVPreF3), or placebo. RESULTS: Solicited local adverse events (AEs) were more frequently reported in the RSVPreF3 groups (4-53.2%) vs placebo (0-15.9%); most were mild/moderate. Unsolicited AEs were comparably reported among groups. Three serious AEs were reported; none was vaccination-related. Compared with pre-vaccination values, anti-RSV A neutralizing antibody geometric mean titers and anti-RSVPreF3 immunoglobulin G geometric mean concentrations increased 8-14-fold and 12-21-fold at day (D)8 and persisted 5-6-fold and 6-8-fold higher until D91 in the RSVPreF3 groups vs 1-fold in placebo. Comparisons at D8 and D31 showed that the higher dose levels were significantly more immunogenic than the lowest one. CONCLUSIONS: The RSVPreF3 vaccine was well tolerated and immunogenic. The 60 and 120 µg dose levels were selected for further investigation in pregnant women.publishedVersionPeer reviewe

Serum albumin and osmolality inhibit Bdellovibrio bacteriovorus predation in human serum

We evaluated the bactericidal activity of Bdellovibrio bacteriovorus, strain HD100, within blood sera against bacterial strains commonly associated with bacteremic infections, including E. coli, Klebsiella pneumoniae and Salmonella enterica. Tests show that B. bacteriovorus HD100 is not susceptible to serum complement or its bactericidal activity. After a two hour exposure to human sera, the prey populations decreased 15- to 7,300-fold due to the serum complement activity while, in contrast, the B. bacteriovorus HD100 population showed a loss of only 33%. Dot blot analyses showed that this is not due to the absence of antibodies against this predator. Predation in human serum was inhibited, though, by both the osmolality and serum albumin. The activity of B. bacteriovorus HD100 showed a sharp transition between 200 and 250 mOsm/kg, and was progressively reduced as the osmolality increased. Serum albumin also acted to inhibit predation by binding to and coating the predatory cells. This was confirmed via dot blot analyses and confocal microscopy. The results from both the osmolality and serum albumin tests were incorporated into a numerical model describing bacterial predation of pathogens. In conclusion, both of these factors inhibit predation and, as such, they limit its effectiveness against pathogenic prey located within sera