Resistive switching effects on the spatial distribution of phases in metal-complex oxide interfaces

In order to determine the key parameters that control the resistive switching mechanism in metal-complex oxides interfaces, we have studied the electrical properties of metal / YBa2Cu3O7-d (YBCO) interfaces using metals with different oxidation energy and work function (Au, Pt, Ag) deposited by sputtering on the surface of a YBCO ceramic sample. By analyzing the IV characteristics of the contact interfaces and the temperature dependence of their resistance, we inferred that ion migration may generate or cancel conducting filaments, which modify the resistance near the interface, in accordance with the predictions of a recent model.Comment: 3 pages, 5 figures, to be published in Physica B. Corresponding author: C. Acha ([email protected]

Cyclic electric field stress on bipolar resistive switching devices

We have studied the effects of accumulating cyclic electrical pulses of increasing amplitude on the non-volatile resistance state of interfaces made by sputtering a metal (Au, Pt) on top of the surface of a cuprate superconductor YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO). We have analyzed the influence of the number of applied pulses $N$ on the relative amplitude of the remnant resistance change between the high ($R_H$) and the low ($R_L$) state [$\alpha=(R_{H}-R_{L})/R_{L}$] at different temperatures ($T$). We show that the critical voltage ($V_c$) needed to produce a resistive switching (RS, i.e. $\alpha >0$) decreases with increasing $N$ or $T$. We also find a power law relation between the voltage of the pulses and the number of pulses $N_{\alpha_0}$ required to produce a RS of $\alpha=\alpha_0$. This relation remains very similar to the Basquin equation used to describe the stress-fatigue lifetime curves in mechanical tests. This points out to the similarity between the physics of the RS, associated with the diffusion of oxygen vacancies induced by electrical pulses, and the propagation of defects in materials subjected to repeated mechanical stress.Comment: 5 pages, 5 figures. To be published in JAP. Corresponding author: [email protected]

Technology Frames: The Art of Perspective and Interpretation in Strategy

In this paper, I bring together the literatures of the economics of innovation, corporate strategy and managerial and organizational cognition to explore how and why companies come to different conclusions and strategies for technology when presented with essentially very similar situations and information. Building on the work of Orlikowski and Gash (1994) on technological frames, I seek to explore the role of the technology frame of key senior managers in defining corporate strategy with respect to technology. To provide an empirical basis for the study, I take the case of the 6 leading US vertically integrated oil companies involved in the exploration and production of petroleum during the period 1984 to 1997. The analysis considers two key salients for the technology frame which are operationalised for the six companies based on their R&D expenditures, patents, publications and contrasted with their operational performance measures. These salients reflect respectively adaptational mapping (whereby signals in the environment prompt adaptation) and formational mapping (whereby experience and path-dependency influence interpretation) within the technology frame. The findings indicate support for the proposed approach to proxying technology frames on the two key points of salience for the upstream petroleum industry, and the paper concludes with a short discussion of future lines of research.technology frames, upstream petroleum, technology strategy, adaptational mapping, formational mapping

Francisco Valsecchi and the Adventures of a Catholic Economic Axiology in 20th Century Argentina

El recorrido intelectual de Francisco Valsecchi (1907-1992) en la historia de las ideas económicas católicas muestra las inflexiones teóricas de una axiología derivada de la Doctrina Social de la Iglesia. Sin embargo, las condiciones históricas del desarrollo de una economía católica en la Argentina y las transformaciones sociales, económicas y políticas del periodo 1930-1970 incidieron sobre las tendencias conceptuales de esa axiología en apariencia perenne. Para explicar los cambios operados se sigue la trayectoria de Valsecchi. Se muestran las fases principales de sus posiciones, destacando tres momentos fundamentales coincidentes con los tres momentos de la economía católica en la Argentina. Al mismo tiempo se muestra la curva teórica de los economistas católicos, que los aleja de una propuesta propiamente católica de una economía política para concentrar su punto de vista en la dimensión ética de las prácticas empresariales. El recorrido intelectual de Valsecchi revela el pasaje de una visión crítica de la economía predominante en 1930 a una funcionalidad con la propuesta en clave antipopulista por las clases propietarias en 1970.The intellectual trajectory of Francisco Valsecchi (1907-1992) in the history of Catholic economic ideas shows the theoretical turns of an axiology derived from the Social Doctrine of the Church. Both the historical circumstances of a Catholic economic thought in Argentina and the social, economic, and political changes of the 1930-1970 period had an impact on the conceptual trends of this apparently perennial axiology. To explain the changes in the economic perspectives the main stages of his theoretical positions are studied, emphasizing the three key moments of Catholic economy. At the same time the article shows the theoretical path followed by Catholic economists from their original proposal of a political economy towards a view orientated to the construction of an axiology of business practices. Valsecchi’s intellectual trajectory reveals the passage from a critical perspective of economy prevailing in the 1930’s to an antipopulist point of view strongly related to the proprietor class in the 1970’s.Fil: Acha, Omar. Universidad de Buenos Aire

Impacts of plug-in hybrid vehicles and combined heat and power technologies on electric and gas distribution network losses

Distribution network operators (DNOs) require strategies that can offset the tradeoffs new embedded technologies have on their assets. This paper employs modelling to show that through control device manipulation, gas and electric (G&E) network operators can influence savings in energy losses under the presence of plug-in hybrid vehicles (PHEVs) and combined heat and power technologies (CHPs). An integrated gas and electric optimal power flow (OPF) tool is introduced to undertake various case studies. The OPF tool evaluates the technical impacts experienced in the networks when DNOs apply a "plug and forget" operation strategy and then compares the results against a "loss minimisation" strategy. Results show the benefits in applying different strategies are more considerable in electric networks than in gas networks. The study corroborates that an integrated G&E analysis offers a fresh perspective for stakeholders in evaluating energy service networks performance under different operation strategies

Transport mechanism through metal-cobaltite interfaces

The resistive switching (RS) properties as a function of temperature were studied for Ag/La$_{1-x}$Sr$_x$CoO$_3$ (LSCO) interfaces. The LSCO is a fully-relaxed 100 nm film grown by metal organic deposition on a LaAlO$_3$ substrate. Both low and a high resistance states were set at room temperature and the temperature dependence of their current-voltage (IV) characteristics was mea- sured taking care to avoid a significant change of the resistance state. The obtained non-trivial IV curves of each state were well reproduced by a circuit model which includes a Poole-Frenkel element and two ohmic resistances. A microscopic description of the changes produced by the RS is given, which enables to envision a picture of the interface as an area where conductive and insulating phases are mixed, producing Maxwell-Wagner contributions to the dielectric properties.Comment: 13 pages, 5 figures, to be published in APL. Corresponding author: C. Acha ([email protected]

Trabajo y delito en las empleadas domésticas durante el primer peronismo: repensar las nociones de lucha y conciencia de clase

Estudio de la conflictividad de clase en el sector de trabajadoras domésticas durante el primer peronismo.Fil: Acha, José Omar. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Saavedra 15. Instituto de Historia Argentina y Americana

Releer Pasado y Presente: ¿por qué, desde dónde y para qué?

Análisis de los esquemas interpretativos predominantes en la investigación sobre la revista Pasado y Presente.Fil: Acha, José Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto de Historia Argentina y Americana "Dr. Emilio Ravignani". Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Historia Argentina y Americana "Dr. Emilio Ravignani"; Argentin

Non-volatile resistive switching in dielectric superconductor YBCO

We report on the reversible, nonvolatile and polarity dependent resistive switching between superconductor and insulator states at the interfaces of a Au/YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO)/Au system. We show that the superconducting state of YBCO in regions near the electrodes can be reversibly removed and restored. The possible origin of the switching effect may be the migration of oxygen or metallic ions along the grain boundaries that control the intergrain superconducting coupling. Four-wire bulk resistance measurements reveal that the migration is not restricted to interfaces and produce significant bulk effects.Comment: 4 pages, 4 figures, corresponding author: C. Acha ([email protected]