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La0·8Ba0·2MnO3, Ba0·25Sr0·75TiO3 and BaTiO3 superlattices were grown to study the influence of structural disorder on the physical properties of multiferroic multilayers. Controlling the lattice mismatch of the superlattices allowed growing structures with different growth mechanisms. The manganite layers in the samples were used as “sensor layers”, that respond to the structural changes in the superlattices, induced by changing the thickness and nature of the ferroelectric layers. Stress has a weak influence on the magnetic properties of these systems. Transport properties are characterized by a high temperature thermally activated regime and a low temperature variable hopping one. The strain and structural disorder in the samples increases the localization energy of the current carriers for both regimes. Important interface effects can be achieved controlling the strain and disorder in the interfaces, allowing tuning the metal-insulator transition temperature. These results help to further understand the role of interface effects in the development of manganite based ferromagnetic/ferroelectric multilayered systems.

Silicon photomultipliers (SiPMs) are novel optoelectronic devices of solid-state technology. They have several advantages with respect to the traditional photomultiplier tubes, such as a superior Photon Detection Efficiency and time resolution. They are compact, mechanically robust, insensitive to magnetic fields and require a relatively low bias voltage, which are attractive characteristics for space-borne applications. In this work, we present the design of an Analog Front-End (AFE) Electronics for SiPMs, optimized for ultra low-light space-borne applications. The system is composed by a transimpedance amplifier and a high speed comparator with differential LVDS output for data transmission. Design considerations are discussed and the fabrication of a prototype is presented, along with analog and digital characterization measurements performed on it.

Artificially engineered superlattices were designed and fabricated to induce different growth mechanisms and structural characteristics. DC sputtering was used to grow ferromagnetic (La0.8Ba0.2MnO3)/ferroelectric (Ba0.25Sr0.75TiO3 or BaTiO3) superlattices. We systematically modified the thickness of the ferromagnetic layer to analyze dimensional and structural disorder effects on the superlattices with different structural characteristics. The crystalline structure was characterized by X-ray diffraction and transmission electron microscopy. The magnetic and electronic properties were investigated by SQUID magnetometry and resistance measurements. The results show that both strain and structural disorder can significantly affect the physical properties of the systems. Ba0.25Sr0.75TiO3 based superlattices with a low thickness of the ferromagnetic layers (4 nm) present compressive strain that decreases the ferromagnetic transition temperature from 250 K corresponding to the unstressed samples to 230 K. In these samples, the localization energy of the charge carrier through the electron-phonon interaction decreases at low temperatures (∼100 meV). Ba0.25Sr0.75TiO3 based superlattices with thicknesses of the ferromagnetic layers higher than 12 nm present tensile strain that reduces the charge carrier localization energy at low temperatures (∼1 meV), increasing the ferromagnetic transition temperature (Tc∼265 K). Structural defects in BaTiO3 based superlattices have a stronger influence on the magnetic properties than on the transport properties. Nevertheless, disorder blocks the ferromagnetic transition for highly disordered samples (thickness of the ferromagnetic layer

We report on the growth and characterization of non-epitaxial but (100)-highly textured BaBiO3 thin films on silicon substrates. We have found the deposition conditions that optimize the texture, and show that the textured growth is favoured by the formation of a BaO layer at the first growth stages. X-ray diffraction Φ-scans, together with the observation that the same textured growth is found on films grown on Pt and SiO2 buffered Si, demonstrate the absence of epitaxy. Finally, we have shown that our (100)-oriented BaBiO3 films can be used as suitable buffers for the growth of textured heterostructures on silicon, which could facilitate the integration of potential devices with standard electronics.

The demand for electronic memories with increasing storage capabilities is always on the rise. Increasing the information density in the same silicon area is a desirable feature, making fast multilevel resistive switching devices a promising candidate. It is thus necessary to design writing and readout circuits that are able to take advantage of the technology's features. In this work, two multibit readout circuits based on non-balanced inverter are presented. The first one is a simple and size reduced flash-type ADC made of inverters, while the second one is a counter-type ADC circuit. Simulations were performed in 0.18 μm CMOS technology using a memristor model extracted from bibliography in order to analyze and compare functionality, power consumption and speed access. The resulting reading time is lower than 1.5 ns for the flash-type ADC and 12 ns for the counter-type ADC. Regarding layout area, the core circuit of the first architecture was implemented in 165 μm2 and the second in 798 μm2.

The LabOSat collaboration (acronym for “Laboratory On a Satellite”) aims to increase the Technology Readiness Level (TRL) of electronic devices and components for space-borne applications. We have developed a single-board electronic platform which is able to operate in space conditions. This board harbors Devices Under Test and performs electric experiments on them. Since 2014, we have participated in six satellite missions (Satellogic small satellites) in Low Earth Orbits, in which we studied the performance of electronic devices such as resistive switching memories and dosimeters based on field-effect transistors. In this work we present our efforts to increase the TRL of Silicon Photomultipliers (SiPMs). In early 2019 we have integrated four 6-mm SiPMs into a 40-kg satellite to study their performance in space. Each SiPM was encapsulated into individual light-tight aluminum housings, which included LEDs for excitation. The SiPMs and the LEDs are operated in DC current mode. Besides the SiPMs current and voltage measurements, the experiment also collects telemetry parameters like temperature, timestamp and orbital position. Fil: Barella, Mariano. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina Fil: Burroni, Tomás Ignacio. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Carsen, Irina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Far, Mónica. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Ferreira Chase, Tomás Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Finazzi, Lucas. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Golmar, Federico. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gomez Marlasca, Fernando. Comisión Nacional de Energía Atómica; Argentina Fil: Izraelevitch, Federico Hernán. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Levy, Pablo. Comisión Nacional de Energía Atómica; Argentina Fil: Sanca, Gabriel. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina

Understanding the effect of fabrication conditions on domain wall (DW) motion in thin films with perpendicular magnetization is a mandatory issue in order to tune their properties aiming to design spintronics devices based on such phenomenon. In this context, the present work intends to show how different growth conditions may affect DW motion in the prototypical system Pt/Co/Pt. The trilayers were deposited by dc sputtering, and the parameters varied in this study were the Co thickness, the substrate roughness and the base pressure in the deposition chamber. Magneto-optical Kerr effect-based magnetometry and microscopy combined with x-ray reflectometry, atomic force microscopy and transmission electron microscopy were adopted as experimental techniques. This permitted us to elucidate the impact on the hysteresis loops and on the DW dynamics, produced by different growth conditions. As other authors, we found that Co thickness is strongly determinant for both the coercive field and the DW velocity. On the contrary, the topographic roughness of the substrate and the base pressure of the deposition chamber evidence a selective impact on the nucleation of magnetic domains and on DW propagation, respectively, providing a tool to tune these properties.

In this paper a CMOS reading circuit for memristor-based RRAM (Resistive Random Access Memory) cell is described. Simulations for one cell, 4 by 4 nMOS-accessed-array and extension to N by N nMOS-accessed-array are presented. The proposed circuit is based on CMOS inverters, which result in a simple low area architecture and in a non-destructive operation. Resistive switching memristor is used as reading reference. Simulations were performed in $0.5\ \mu \text{m}$ and 180 nm CMOS technology and using memristor model available in bibliography.

Microfluidic devices are a new platform for Enhanced Oil Recovery (EOR) assays. A successful oil recoveryin a reservoir can be different in another, hence the importance of a methodology for assessment prior toinjection. In the current study, micro and nanotechnology techniques were applied to develop EOR assays.The EOR chips simulated the phenomena occurred in micro-nano scale reservoirs. In general, the first step ofthe experiments corresponded to fill the microchannels with oil, then was injected water at constant flow rateuntil oil recovery ceases and finally was injected polymer or CDG. The recovery behaviors of the fluids werestudied by digital image analysis. Results allowed obtaining oil recovery for each evaluated fluid. Theoptimum configuration of the microchannels showed 80% of oil residual saturation after water injection.Keywords: EOR, poral volume, microgels and polymers, microfuidic devices. Fil: Rosero Yánez, Gustavo Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina Fil: Peñaherrera Pazmiño, Ana Belén. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Olmos Carreno, Carol Maritza. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina Fil: Boschan, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina Fil: Granell, Pablo Nicolás. Instituto Nacional de Tecnología Industrial; Argentina Fil: Golmar, Federico. Instituto Nacional de Tecnología Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lasorsa, Carlos Alberto. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina Fil: Lerner, Betiana. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Perez, Maximiliano Sebastian. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina

We report on the fabrication and characterization of La2/3Ca1/3MnO3 manganite-based memristive devices. Polycrystalline manganite thin films were grown by Pulsed Laser Deposition, while metallic electrodes were deposited by sputtering. We show that, depending on the polarity of the initial electroforming, both clockwise and anti-clockwise current-voltage curves can be obtained. We attribute this behavior to the coexistence of different resistive switchingmechanisms.We finally evaluate the electrical behavior of our devices after irradiation with high energy oxygen ions. We find no significant difference in the dielectric breakdown voltages between irradiated and non-irradiated devices, indicating that they may present radiation hardness and could be therefore appropriate for space or nuclear applications. Fil: Rubi, Diego. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Kalstein, Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Roman Acevedo, Wilson Stibens. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Ghenzi, Néstor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Quinteros, Cynthia Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Mangano, E.. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario. Unidad Técnica de Micro y Nano Sistemas; Argentina Fil: Granell, Pablo Nicolás. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario. Unidad Técnica de Micro y Nano Sistemas; Argentina Fil: Golmar, Federico. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario. Unidad Técnica de Micro y Nano Sistemas; Argentina Fil: Marlasca, F. G.. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Suarez, Sergio Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Bernardi, Guillermo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Albornoz, C.. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Leyva de Guglielmino, Ana Gabriela. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina Fil: Levy, Pablo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina

Phone: þ34 943 574012, Fax: 34 943 574001We present performance characteristics of nanoscaled cobaltphthalocyanine (CoPc)-based organic field-effect transistors(OFETs) as a function of channel length. We found a channellength range which maximizes the field effect mobility in atrade-off between the decrease in the number of organic grainboundaries and the increase of the electrode–organic contactregion. Further reduction of channel length is limited by fringecurrents, which lead to an increased off current and to adegradation of the sub-threshold slope. From this, we definean optimal channel length of 280nm to 1mm for applicationsin submicrometric CoPc-based OFETs. Our results are particu-larly relevant for the miniaturization of chemical sensingOFETs, where metal phthalocyanines have proven to beexcellentcandidatesforthefabricationofthetransistorchannel.

In this work the characteristics and performance of LabOSat platform to carry out experiments over electronic devices in aggressive environments are described. Configurable, portable, low weight and low cost are the main features. First measurements made in our laboratory are presented before testing in space.

We study micrometer-sized organic field-effect transistors with either Pd or NiFe metallic electrodes. Neither of these materials is commonly used in organic electronics applications, but they could prove to be particularly advantageous in certain niche applications such as organic spintronics. Using organic semiconductors with different carrier transport characteristics as active layer, namely n-type C60 fullerene and p-type Pentacene, we prove that Pd (NiFe) is a very suitable electrode for p- (n-) type semiconductors. In particular, we characterized devices with channel lengths in the order of the micrometer, a distance which has allowed us to evaluate the electronic behavior in a regime where the interfacial problems become predominant and it is possible to reach elevated longitudinal electric fields. Our experimental results agree well with a simple model based on rigid energy levels.

We study the propagation of mid-infrared surface plasmons on non-tapered and tapered two-wire transmission lines on Si and CaF2 substrates, the two materials representing substrates with large and small refractive index, respectively. A comparative numerical study predicts a larger effective wavelength and an increased propagation length (i.e. weaker damping) for the CaF2 substrate. By near-field microscopy we image the near-field distribution along the transmission lines and experimentally verify surface plasmon propagation. Amplitude- and phase-resolved near-field images of a non-tapered transmission line on CaF2 reveal a standing wave pattern caused by back-reflection of the surface plasmons at the open-ended transmission line. Calculated and experimental near-field images of tapered transmission lines on Si and CaF2 demonstrate that for both substrates the mid-IR surface plasmons are compressed when propagating along the taper. Importantly, the nanofocus at the taper apex yields a stronger local field enhancement for the low-refractive index substrate CaF2. We assign the more efficient nanofocusing on CaF2 to the weaker damping of the surface plasmons.

Spintronics based on ferromagnetic metals and organic semiconductors has attracted great interest in recent years. Molecular-based spintronic devices, such as magnetic tunnel junctions, have been demonstrated with performances competing with those of conventional inorganic devices. Still, there is huge margin for improvement, as many details about the injection of spin-polarized electrons into the molecular layer remain not completely understood. In order to achieve better understanding and control of the physical mechanisms, it is necessary to explore various combinations of ferromagnetic metals and organic semiconductors. In this letter, we study the properties of the combination between the ferromagnetic metal NiFe (commonly known as Permalloy or Py) and the molecular system C 60 . We produced C 60 /Py bilayers and characterized them structurally, electrically and magnetically. The C 60 films grow smoothly on both Py and SiO 2 substrates, and we estimate that a 5-nm-thick C 60 film covers completely the surface underneath without leaving pinholes and can be therefore used in a vertical device, as confirmed by electrical characterization. Furthermore, the C 60 film is robust against the deposition of the top metal electrode, being the intermixing layer of only 1–2 nm at the C 60 /Py interface. Finally, we show that the magnetic properties of Py are not affected by the deposition sequence, and that a 5-nm-thick Py layer on top of a C 60 layer keeps its magnetic properties intact. These results show that the combination between Py and C 60 provides a robust template platform for the development of molecular spintronics, and can be used later on for more sophisticated investigations, such as the role of the interfaces in the spin injection.

We have studied the influence of intrinsic and extrinsic defects in the magnetic and electrical transport properties of Co-doped ZnO thin films. X ray absorption measurements show that Co substitute Zn in the ZnO structure and it is in the 2+ oxidation state. Magnetization (M) measurements show that doped samples are mainly paramagnetic. From M vs. H loops measured at 5 K we found that the values of the orbital L and spin S numbers are between 1 and 1.3 for L and S = 3/2, in agreement with the representative values for isolated Co 2+. The obtained negative values of the Curie-Weiss temperatures indicate the existence of antiferromagnetic interactions between transition metal atoms., Comment: To be published in Journal of Materials Science

Transparent pure and Fe-doped SnO 2 thin films were grown by pulsed laser deposition technique on LaAlO 3 substrates. X-ray diffraction shows that the films are polycrystalline and have the rutile structure. Surprisingly, the pure film presents magnetic-like behavior at room temperature with a saturated magnetization of almost one-third of the doped film (∼3.6 and 11.3 emu/g, respectively) and its magnetization could not be attributed to any impurity phase. Taking into account the magnetic moment measured in the pure film, the effective contribution of the impurity in the doped one can be inferred to be ∼2 μ B per Fe atom. A large magnetic moment was also predicted by an ab initio calculation in the doped system, which increases if an oxygen vacancy is present near the Fe impurity.

In this work, we investigate the polarity-dependent Electric Pulses Induced Resistive (EPIR) switching phenomenon in thin films driven by electric pulses. Thin films of 0.5Ca0.5MnO3 (manganite) were deposited by PLD on Si substrate. The transport properties at the interface between the film and metallic electrode are characterized in order to study the resistance switching. Sample thermal treatment and electrical field history are important to be considered for get reproducible EPIR effect. Carriers trapping at the interfaces are considered as a possible explanation of our results.

Transition-Metal-doped TiO2 thin films, with nominal composition Ti₀.₉TM₀₁O₂-δ (TM = Mn, Fe, Co, Ni, Cu), were grown by pulsed laser deposition (PLD), in order to study the role of dopants in the origin and significance of room temperature ferromagnetism in these systems. The crystallographic structures and their magnetic properties were characterized and the experimental results are compared to ab-initio calculations previously reported. The films are ferromagnetic at room temperature in the cases of Fe, Co, Ni and even Cu impurities, but not in the case of Mn doping. Our results support the hypothesis that oxygen vacancies play a key role in the origin of magnetism in doped TiO2 films, and can explain the diversity of magnetic moments observed experimentally for films grown under different conditions., Instituto de Física La Plata

We report on magnetotransport properties on La_(0.7)Sr_(0.3)MnO_(3)/MgO/Fe tunnel junctions grown epitaxially on top of (001)-oriented SrTiO_(3) substrates by sputtering. It is shown that the magnetoresistive response depends critically on the MgO/Fe interfacial properties. The appearance of an FeOX layer by the interface destroys the 1 symmetry filtering effect of the MgO/Fe system and only a small negative tunneling magnetoresistance (TMR) (∼ −3 %) is measured. However, in annealed samples a switchover from positive TMR (∼ +25% at 70 K) to negative TMR (∼ −1 %) is observed around 120 K. This change is associated with the transition from semiconducting at high T to insulating at low T taking place at the Verwey transition (TV ∼ 120 K) in Fe3O4, thus suggesting the formation of a very thin slab of magnetite at the MgO/Fe interface during annealing treatments. These results highlight the relevance of interfacial properties on the tunneling conduction process and how it can be substantially modified through appropriate interface engineering.

The distribution of boron in tissue samples coming from boron neutron capture therapy protocols can be determined through the analysis of its autoradiography image on a nuclear track detector. A more precise knowledge of boron atom location on the microscopic scale can be attained by the observation of nuclear tracks superimposed on the sample image on the detector. A method to produce an “imprint” of cells cultivated on a polycarbonate detector was developed, based on the photodegradation properties of UV-C radiation on this material. Optimal conditions to generate an appropriate monolayer of Mel-J cells incubated with boronophenylalanine were found. The best images of both cells and nuclear tracks were obtained for a neutron fluence of 1013cm−2, 6 h UV-C (254 nm) exposure, and 4 min etching time with a KOH solution. The imprint morphology was analyzed by both light and scanning electron microscopy. Similar samples, exposed to UV-A (360 nm) revealed no cellular imprinting. Etch pits were present only inside the cell imprints, indicating a preferential boron uptake (about threefold the incubation concentration). Comparative studies of boron absorption in different cell lines andin vitroevaluation of the effect of diverse boron compounds are feasible with this methodology.

We report the electrical transport properties of conducting/insulator/conducting heterostructures by studying current-voltage IV curves at room temperature. The measurements were obtained on tunnel junctions with different areas (900, 400 and 100 μm2) using a conducting atomic force microscope. Trilayers with GdBa2Cu3O7 (GBCO) as the bottom electrode, SrTiO3 or BaTiO3 (thicknesses between 1.6 and 4 nm) as the insulator barrier, and GBCO or Nb as the top electrode were grown by DC sputtering on (100) SrTiO3 substrates For SrTiO3 and BaTiO3 barriers, asymmetric IV curves at positive and negative polarization can be obtained using electrodes with different work function. In addition, hysteretic IV curves are obtained for BaTiO3 barriers, which can be ascribed to a combined effect of the FE reversal switching polarization and an oxygen vacancy migration. For GBCO/BaTiO3/GBCO heterostructures, the IV curves correspond to that expected for asymmetric interfaces, which indicates that the disorder affects differently the properties at the bottom and top interfaces. Our results show the role of the interface disorder on the electrical transport of conducting/insulator/conduction heterostructures, which is relevant for different applications, going from resistive switching memories (at room temperature) to Josephson junctions (at low temperatures). Fil: Navarro Fernández, Henry Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina Fil: Sirena, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina Fil: Gonzalez Sutter, Jesus Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina Fil: Troiani, Horacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina Fil: del Corro, Pablo Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina Fil: Granell, Pablo Nicolás. Instituto Nacional de Tecnología Industrial; Argentina Fil: Golmar, Federico. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Haberkorn, Nestor Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina

We report on the influence of oxygen stoichiometry on the vortex creep mechanism of GdBa2Cu3O x -coated conductors produced by co-evaporation. The oxygen stoichiometry of the films, x, was modified in a controlled way between 6.85 and 7, which resulted in systematic and reversible control of the superconducting critical temperature between about 78 and 93 K. The change in the oxygen stoichiometry produces a strong reduction in the self-field critical current densities J c without significantly modifying the power-law dependence at intermediate magnetic fields, which indicates a negligible contribution of oxygen vacancies to the pinning. In addition, the characteristic glassy exponent ? shows a systematic diminution from about 1.63 at x?=?7 to about 1.12 at x?=?6.85. The results are compared with those obtained for proton- and oxygen-irradiated films, in which the vortex dynamics is determined by a balance between the improved pinning, originating from nanocluster inclusion, and the suppressed superconducting properties due to disorder in the nanoscale.

This work probes the relevance of oxygen vacancies in the formation of local ferromagnetic coupling between Fe ions at octahedral sites in zinc ferrites. This coupling gives rise to a ferrimagnetic ordering with the Curie temperatures above room temperature in an otherwise antiferromagnetic compound. This conclusion is based on experimental results from x-raymagnetic circular dichroismmeasurements at the Fe L2,3 edges and magnetization measurements performed on zinc ferrites, nanoparticles, and films, with different cation distributions and oxygen vacancy concentrations. Our observations are confirmed by density-functional-theory calculations and indicate that the enhanced ferrimagnetic response observed in some nominally nonmagnetic or antiferromagnetic ferrites can be taken as a further example of the defect-induced magnetism phenomenon. Fil: RodrÍguez Torres, Claudia Elena. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina Fil: Pasquevich, Gustavo Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina Fil: Mendoza Zélis, Pedro. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina Fil: Golmar, Federico. CIC Nanogune; España. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pérez, Silvia Inés. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Sólido; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Nayak, Sanjeev K.. Martin Luther University Halle-Wittenberg; Alemania Fil: Adeagbo, Waheed A.. Martin Luther University Halle-Wittenberg; Alemania Fil: Hergebert, Wolfram. Martin Luther University Halle-Wittenberg; Alemania Fil: Hoffmann, Martin. Martin Luther University Halle-Wittenberg; Alemania. Institut Max Planck of Microstructure Physics; Alemania Fil: Ernst, Arthur. Institut Max Planck of Microstructure Physics; Alemania Fil: Esquinazi, P.. University of Leipzig; Alemania Fil: Stewart, Silvana Jacqueline. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina

Transparent pure and Cu-doped (2.5, 5 and 10 at.%) anatase TiO 2 thin films were grown by pulsed laser deposition technique on LaAlO 3 substrates. The samples were structurally characterized by X-ray absorption spectroscopy and X-ray diffraction. The magnetic properties were measured using a SQUID. All films have a FM-like behaviour. In the case of the Cu-doped samples, the magnetic cycles are almost independent of the Cu concentration. Cu atoms are forming CuO and/or substituting Ti in TiO 2 . The thermal treatment in air promotes the CuO segregation. Since CuO is antiferromagnetic, the magnetic signals present in the films could be assigned to Cu substitutionally replacing cations in TiO 2 .

Resistance random access memory (ReRAM) is considered a promising candidate for the next generation of non-volatile memory. In this work, we fabricate Co/HfO2/Ti devices incorporating atomic-layer-deposited HfO 2 thin films as the active material grown under different atomic layer deposition (ALD) conditions. We focus on analyzing the effect of ALD conditions on the resistive switching behaviour of the devices. Electrical characterization reveals a particular non-crossing current-voltage curve and bipolar resistive switching behaviour. Device memory properties were confirmed by stability and retention measurements as well as voltage pulses, by which logical computational processes were conducted. X-ray photoelectron spectroscopy combined with electrical measurements demonstrates that the presence of Hf sub-oxides at the interface with the underlying Ti layer is required in order to achieve a stable switching device. The ability of Ti to scavenge oxygen from the HfO2 is shown to be affected by the ALD conditions. This journal is © the Partner Organisations 2014., We also acknowledge funding support from Juan de la Cierva Program JCI-2010-07837 and by projects MAT2009-08494, MAT2010-21156-C03-03 and MAT2012-37638 from the Spanish Ministry of Science, by the Basque Government through Project nos PI2011-1 and IT-621-13 as well as a Marie Curie Reintegration Grant (ITAMOSCINOM) from the European Commission.

Theory predicts a distinct spectral shift between the near- and far-field optical response of plasmonic antennas. Here we combine near-field optical microscopy and far-field spectroscopy of individual infrared-resonant nanoantennas to verify experimentally this spectral shift. Numerical calculations corroborate our experimental results. We furthermore discuss the implications of this effect in surface-enhanced infrared spectroscopy. © 2013 American Physical Society., This work was supported by the European FP7 Project ‘‘Nanoantenna’’ (No. FP7-HEALTH-F5-2009-241818-NANOANTENNA), the Spanish National Projects No. MAT2009-08398 and No. FIS2010-19609-C02-01, and the Basque Government Projects ETORTEK (nanoIKER) and excellence program IT756-13.

We report the critical current densities Jc and flux creep rates in a 2 mm thick SmBa2Cu3O7-dcoated conductor produced by co-evaporation. The sample presents strong pinning produced by correlated disorder (boundaries between growth islands, dislocations and twin boundaries) as well as random nanoparticles. Correlated pinning along the c- axis was evidenced due to the appearance of a large peak in the angular critical current, centred at H ║ c. The analysis of the critical current density Jc (with the magnetic field applied parallel (H║c) and at 45° of the c-axis (H║45°)) indicates that correlated disorder assists pinning throughout the temperature range. For all temperatures and at both angles the in-field dependence of Jc exhibits a power-law behavior. The contribution of correlated disorder drops when the field is rotated to intermediate angles between the c axis and a-b axis (i. e. H║45°), which derives in a reduction of the absolute Jc value and poorer in-field dependences. The flux creep rate depends on the angle and its values remain approximately constant within 2 the power-law regime. For H║c and H║45° and for magnetic fields lower than 20 kOe, the flux relaxation presents characterizing glassy exponents u = 1.70 and u =1.32, respectively. Fil: Haberkorn, Nestor Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Coulter, Y.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Condo, Adriana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Granell, Pablo Nicolás. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario; Argentina Fil: Golmar, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Ha, H. S.. Korea Electrotechnology Research Institute; Corea del Norte Fil: Moon, S. H.. SuNAM Co; Corea del Norte

Sketch of the configuration of a light-controlled resistive switching memory. Light enters through the Al(2) O(3) uncovered surface and reaches the optically active p-Si substrate, where carriers are photogenerated and subsequently injected in the Al(2) O(3) layer when a suitable voltage pulse is applied. The resistance of the Al(2) O(3) can be switched between different non-volatile states, depending on the applied voltage pulse and on the illumination conditions.

X-ray absorption near-edge and grazing incidence x-ray fluorescence spectroscopy are employed to investigate the electronic structure of ZnFe${}_{2}$O${}_{4}$ thin films. The spectroscopy techniques are used to determine the nonequilibrium cation site occupancy as a function of depth and oxygen pressure during deposition and its effects on the magnetic properties. It is found that low deposition pressures below 10${}^{\ensuremath{-}3}$ mbar cause iron superoccupation of tetrahedral sites without Zn${}^{2+}$ inversion, resulting in an ordered magnetic phase with high room-temperature magnetic moment.

N-doped ZnO thin films were deposited by pulsed laser deposition on SiO2/Si substrates. X-ray diffraction analysis revealed that the films had the wurtzite structure, and were highly oriented along the c-axis direction. Au and Al electrical contacts were deposited by sputtering on the top surface of the samples, forming a two-terminal structure in each case. The current-voltage characteristics of the two terminal structure, and the temperature dependence of the resistance switching effect, were studied in the 125-300 K temperature range. The results of these measurements are presented and discussed in terms of the different Schottky barrier heights, as well as in terms of interfacial defect-induced gap states.

We report here the unexpected observation of significant room-temperature ferromagnetism in a semiconductor doped with nonmagnetic impurities, Cu-doped TiO₂ thin films grown by pulsed laser deposition. The magnetic moment, calculated from the magnetization curves, resulted surprisingly large, about 1.5 μB per Cu atom. A large magnetic moment was also obtained from ab initio calculations, but only if an oxygen vacancy in the nearest-neighbor shell of Cu was present. This result suggests that the role of oxygen vacancies is crucial for the appearance of ferromagnetism. The calculations also predict that Cu doping favors the formation of oxygen vacancies., Facultad de Ciencias Exactas, Instituto de Física La Plata

We report magnetoresistance measurements on thin Pt bars grown on epitaxial (001) and (111) CoFe2O4 (CFO) ferrimagnetic insulating films. The results can be described in terms of the recently discovered spin Hall magnetoresistance (SMR). The magnitude of the SMR depends on the interface preparation conditions, being optimal when Pt/CFO samples are prepared in situ, in a single process. The spin-mixing interface conductance, the key parameter governing SMR and other relevant spin-dependent phenomena such as spin pumping or spin Seebeck effect, is found to be different depending on the crystallographic orientation of CFO, highlighting the role of the composition and density of magnetic ions at the interface on spin mixing., Comment: 13 pages, 5 figures

Scaling down organic field effect transistors to channel areas well below the micron square could improve positively its speed and integration capabilities. Here, we report a careful study of the electronic carrier transport for such nanoscale devices. In particular, we explore the validity of standard analysis for parameters extraction in this size regime. We also study the effect of the large longitudinal electric field and fringe currents, especially their influence on the ON/OFF ratio.

Commercial LaAlO3 substrates were thermally cycled simulating a procedure similar to those followed during TiO2 and SnO2 dilute magnetic semiconductors’ film pulsed laser deposition. Ferromagneticlike behavior was found in some substrates, in which metallic iron impurities were detected by x-ray photoelectron spectroscopy and total reflection x-ray fluorescence measurements. A thorough experimental investigation, using high resolution techniques, showed that these impurities were introduced by the procedure used to fix the substrates to the oven silicon holders. It is suggested that magnetism observed previously in nominally pure SnO2 films is of extrinsic origin.