Creation of equal-spin triplet superconductivity at the Al/EuS interface

In conventional superconductors, electrons of opposite spins are bound into Cooper pairs. However, when the superconductor is in contact with a non-uniformly ordered ferromagnet, an exotic type of superconductivity can appear at the interface, with electrons bound into three possible spin-triplet states. Triplet pairs with equal spin play a vital role in low-dissipation spintronics. Despite the observation of supercurrents through ferromagnets, spectroscopic evidence for the existence of equal-spin triplet pairs is still missing. Here we show a theoretical model that reveals a characteristic gap structure in the quasiparticle density of states which provides a unique signature for the presence of equal-spin triplet pairs. By scanning tunnelling spectroscopy we measure the local density of states to reveal the spin configuration of triplet pairs. We demonstrate that the Al/EuS interface causes strong and tunable spin-mixing by virtue of its spin-dependent transmission.Comment: 10 pages, 4 figures, 17 pages supplementary information, 14 supplementary figure

Kehlkopfveränderungen und plötzlicher Tod

Mehrere in letzter Zeit beobachtete Fälle eines ldquoplötzlichen Todesrdquo durch Kehlkopfveränderungen gaben Anlaß zur eingehenden Erörterung dieser Problematik, zumal im Institut für Rechtsmedizin der Universität München unter 10 747 Obduktionen in den Jahren 1949 bis 1970 nur 6 Fälle gefunden wurden. Nach einer kurzen Beschreibung des anatomischen Aufbaues vom Kehlkopf werden entsprechend der in der allgemeinen Pathologie benutzten Gliederung die 4 Faktoren angeführt, die ätiologisch Ursache eines Kehlkopfverschlusses sein können: 1. Fehlbildungen 2. Kreislaufstörungen 3. Entzündungen 4. Geschwulstbildungen. Jeder der genannten Faktoren wird gesondert erörtert und die Fälle aus unserem Beobachtungsgut ihnen entsprechend zugeordnet. Neben der Frage nach der rechtsmedizinischen Bedeutung derartiger Todesfälle wird die Schwierigkeit der Beurteilung mancher pathomorphologischer und feingeweblicher Befunde diskutiert. Gleichzeitig wird auf die oft leere Anamnese hingewiesen, so daß lebensrettende Maßnahmen, wie zum Beispiel die Notfalltracheotomie und anderes, gar nicht oder sehr spät einsetzen können. Abschließend wird die Problematik der forensischen Begutachtung diskutiert, die sich bei der Abgrenzung der Larynxzysten hinsichtlich ihrer Ätiologie ergibt. Hier ist die Abklärung eines Kausalzusammenhanges zu eventuell vorangegangenen Intubationen von besonderer Bedeutung

Andreev and normal reflections in gapped bilayer graphene-superconductor junctions

We study the Andreev and normal reflection processes -- retro as well as specular -- in a bilayer graphene-superconductor junction where equal and opposite displacement fields are applied for the top and bottom layers to induce a band gap. By employing the Dirac-Bogoliubov-de Gennes equation for the gapped bilayer graphene-superconductor junction, we calculate the reflections probabilities within the scattering theory approach. The subgap conductance, calculated in the framework of Blonder-Tinkham-Klapwijk formalism, shows the contribution from the Andreev retro-reflection (specular-reflection) when the applied bias voltage is below (above) the Fermi energy. Notably, both retro and specular reflections are modified in the presence of the displacement field, and the retro-to-specular crossover gets amplified when the displacement field is relatively small. They can be further tuned to either specular or retro Andreev reflection by adjusting the Fermi energy. Furthermore, our study reveals the simultaneous existence of double Andreev reflections and double normal reflections when the displacement field becomes comparable to the interlayer coupling strength. The existence of the normal retro-reflection process in a bilayer graphene-superconductor junction is a new finding which shows a distinctive feature in the conductance that can be experimentally verified.Comment: 11 pages, 9 figure

Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

Background: Thermoelectric effects result from the coupling of charge and heat transport and can be used for thermometry, cooling and harvesting of thermal energy. The microscopic origin of thermoelectric effects is a broken electron-hole symmetry, which is usually quite small in metal structures. In addition, thermoelectric effects decrease towards low temperatures, which usually makes them vanishingly small in metal nanostructures in the sub-Kelvin regime. Results: We report on a combined experimental and theoretical investigation of thermoelectric effects in superconductor/ferromagnet hybrid structures. We investigate the dependence of thermoelectric currents on the thermal excitation, as well as on the presence of a dc bias voltage across the junction. Conclusion: Large thermoelectric effects are observed in superconductor/ferromagnet and superconductor/normal-metal hybrid structures. The spin-independent signals observed under finite voltage bias are shown to be reciprocal to the physics of superconductor/normal-metal microrefrigerators. The spin-dependent thermoelectric signals in the linear regime are due to the coupling of spin and heat transport, and can be used to design more efficient refrigerators

The bivalve Anopaea (Inoceramidae) from the Upper Jurassic-lowermost Cretaceous of Mexico

In Mexico, the Upper Jurassic to lowermost Cretaceous La Casita and coeval La Caja and La Pimienta formations are well-known for their abundant and well-preserved marine vertebrates and invertebrates. The latter include conspicuous inoceramid bivalves of the genus Anopaea not formally described previously from Mexico. Anopaea bassei (Lecolle de Cantú, 1967), Anopaea cf. stoliczkai (Holdhaus, 1913), Anopaea cf. callistoensis Crame and Kelly, 1995 and Anopaea sp. are rare constituents in distinctive Tithonian–lower Berriasian levels of the La Caja Formation and one Tithonian horizon of the La Pimienta Formation. Anopaea bassei was previously documented from the Tithonian of central Mexico and Cuba, while most other members of Anopaea described here are only known from southern high latitudes. The Mexican assemblage also includes taxa which closely resemble Anopaea stoliczkai from the Tithonian of India, Indonesia and the Antarctic Peninsula, and Anopaea callistoensis from the late Tithonian to ?early Berriasian of the Antarctic Peninsula. Our new data expand the palaeogeographical distribution of the high latitude Anopaea to the Gulf of Mexico region and substantiate faunal exchange, in the Late Jurassic–earliest Cretaceous, between Mexico and the Antarctic Realm