Identit\ue0, stampa e regimi: un trinomio indivisibile. Percorsi di lettura

Introduzione al volume: C. Prestigiacomo (a cura di), Identit\ue0, totalitarismi e stampa. Ricodifica linguistico-culturale dei media di regime, Palermo, UniPapress, 2016. Si espone lo stretto rapporto che intercorre tra potere (soprattutto totalitario), stampa e costituzione dell'identit\ue0 del cittadino e di gruppo. SI illustrano i saggi che compongono il volum

Patente de corso y La zona fantasma: estrategias argumentativas y (des)cortes\ueda instrumental

This study deals with the pragmatic-linguistic strategies used by enunciators (or enunciators-locutors), Javier Mar\uedas (La zona fantasma) and Arturo P\ue9rez Reverte (Patente de corso). After a brief introduction on argumentative discourse and the opinion columns, the role of the enunciator and their attitude toward the direct and indirect addressee is analysed in detail. More precisely, the article will demonstrate how elements, including mode; neologisms; imperative; interrogative sentences and also the \u2018instrumental (im)politeness\u2019 (or ironic tone) support persuasive objective that this kind of discourse pursues.En este trabajo proponemos una reflexi\uf3n sobre las estrategias pragm\ue1tico-ling\ufc\uedsticas a las que recurren constantemente los enunciadores (o enunciadores-locutores) J. Mar\uedas (La zona fantasma) y A. P\ue9rez Reverte (Patente de corso). En concreto, despu\ue9s de una breve introducci\uf3n sobre el discurso argumentativo y las columnas de autor, se analizar\ue1n la figura del enunciador y la actitud que este demuestra con respecto al destinatario, directo e indirecto. Cada elemento (modalidad, formaciones neol\uf3gicas, enunciados imperativos e interrogativos), incluso la descortes\ueda instrumental (o el tono ir\uf3nico), se ver\ue1 como recurso estrat\ue9gico al servicio del objetivo persuasivo que genera este tipo de discurso

Asymmetric Avalanches in the Condensate of a Zeeman-limited Superconductor

We report the non-equilibrium behavior of disordered superconducting Al films in high Zeeman fields. We have measured the tunneling density of states of the films through the first-order Zeeman critical field transition. We find that films with sheet resistances of a few hundred ohms exhibit large avalanche-like collapses of the condensate on the superheating branch of the critical field hysteresis loop. In contrast, the transition back into the superconducting phase (i.e., along the supercooling branch) is always continuous. The fact that the condensate follows an unstable trajectory to the normal state suggests that the order parameter in the hysteretic regime is not homogeneous.Comment: 5 pages, 5 figures, to appear in PR

Spin-Mediated Transport in Superconducting and Spin-Polarized Systems

The effects of spin-imbalance on the electronic transport properties of spin-polarized and superconducting systems have been studied in detail. The transport properties of the quaternary Heusler alloys Co2MnSi1-xAlx (0≤x≤1), which have been theoretically predicted to develop a half-metallic band structure as x→0, were investigated. Resistivity versus temperature measurements as a function of Al concentration (x) revealed a systematic reduction in the residual resistivity ratio as well as a transition from weakly-localized to half-metallic conduction as x→0. From measurements of the ordinary and anomalous Hall effects, the charge carrier concentration was found to increase, while the anomalous Hall coefficient decreased by nearly an order of magnitude with each sample as x→0 (∆x=0.25). Scaling of the anomalous Hall effect with longitudinal resistivity reveals that both the skew-scattering and intrinsic contributions grow quickly as x→1, indicating that disorder and band-structure effects cause the large anomalous Hall effect magnitudes observed for Co2MnAl. The non-equilibrium behavior of disordered superconducting Al films in high Zeeman fields has also been investigated. The tunneling density-of-states of the films were measured through the first-order Zeeman critical field transition. It is found that films with sheet resistances of a few hundred ohms exhibit large avalanche-like collapses of the condensate on the super-heating branch of the critical field hysteresis loop. In contrast, the transition back into the superconducting phase (i.e., along the super-cooling branch) is always continuous. These avalanches are suppressed by tilting the field as little as 1.5° and disappear above T = 300 mK, although the transition remains hysteretic. The fact that the condensate follows an unstable trajectory to the normal state suggests that the order-parameter in the hysteretic regime is not homogeneous. It is argued that this unusual behavior is a manifestation of the disordered Larkin-Ovchinnikov phase, which is a disordered remnant of the elusive, spin-imbalanced superconducting state known as the Fulde-Ferrell-Larkin-Ovchinnikov phase

Exchange Field-Mediated Magnetoresistance in the Correlated Insulator Phase of Be Films

We present a study of the proximity effect between a ferromagnet and a paramagnetic metal of varying disorder. Thin beryllium films are deposited onto a 5 nm-thick layer of the ferromagnetic insulator EuS. This bilayer arrangement induces an exchange field, $H_{ex}$, of a few tesla in low resistance Be films with sheet resistance $R\ll R_Q$, where $R_Q=h/e^2$ is the quantum resistance. We show that $H_{ex}$ survives in very high resistance films and, in fact, appears to be relatively insensitive to the Be disorder. We exploit this fact to produce a giant low-field magnetoresistance in the correlated insulator phase of Be films with $R\gg R_Q$.Comment: To be published in Physical Review Letter

Asymmetric avalanche behavior in a zeeman-limited superconductor

We have performed transport and tunneling density of states measurements of ultra-thin Al films through The first-order parallel critical field transition. The transition is intrinsically hysteretic and exhibits avalanche-like jumps in both resistivity and tunneling density states. Tunneling measurements on films with sheet resistances of a few hundred ohms show large avalanche-like collapses of The condensate on The superheating branch of The critical field hysteresis loop. In contrast, The transition back into The superconducting phase (i.e., along The supercooling branch) is always continuous

Electrostatic tuning of the proximity-induced exchange field in EuS/Al bilayers

We demonstrate that the proximity-induced exchange field Hex in ferromagnetic-paramagnetic bilayers can be modulated with an electric field. An electrostatic gate arrangement is used to tune the magnitude of Hex in the Al component of EuS/Al bilayers. In samples with Hex∼2 T, we were able to produce modulations of ±10 mT with the application of perpendicular electric fields of the order of ±106 V/cm. We discuss several possible mechanisms accounting for the electric field\u27s influence on the interfacial coupling between the Al layer and the ferromagnetic insulator EuS, along with the prospects of producing a superconducting field-effect transistor. © 2013 American Physical Society

Magnetic, thermodynamic, and electrical transport properties of the noncentrosymmetric B20 germanides MnGe and CoGe

We present magnetization, specific heat, resistivity, and Hall effect measurements on the cubic B20 phase of MnGe and CoGe and compare to measurements of isostructural FeGe and electronic structure calculations. In MnGe, we observe a transition to a magnetic state at $T_c=275$ K as identified by a sharp peak in the ac magnetic susceptibility, as well as second phase transition at lower temperature that becomes apparent only at finite magnetic field. We discover two phase transitions in the specific heat at temperatures much below the Curie temperature one of which we associate with changes to the magnetic structure. A magnetic field reduces the temperature of this transition which corresponds closely to the sharp peak observed in the ac susceptibility at fields above 5 kOe. The second of these transitions is not affected by the application of field and has no signature in the magnetic properties or our crystal structure parameters. Transport measurements indicate that MnGe is metal with a negative magnetoresistance similar to that seen in isostructural FeGe and MnSi. Hall effect measurements reveal a carrier concentration of about 0.5 carriers per formula unit also similar to that found in FeGe and MnSi. CoGe is shown to be a low carrier density metal with a very small, nearly temperature independent diamagnetic susceptibility.Comment: 16 pages 23 figure