Superconducting density of states at the border of an amorphous thin film grown by focused-ion-beam

We present very low temperature Scanning Tunneling Microscopy and Spectroscopy (STM/S) measurements of a W based amorphous thin film grown with focused-ion-beam. In particular, we address the superconducting properties close to the border, where the thickness of the superconducting film decreases, and the Au substrate emerges. When approaching the Au substrate, the superconducting tunneling conductance strongly increases around the Fermi level, and the quasiparticle peaks do not significantly change its position. Under magnetic fields, the vortex lattice is observed, with vortices positioned very close to the Au substrate.Comment: To appear in Journal of Physics: Conference serie

Las barreras y los obstáculos en el acceso de las profesoras universitarias a los cargos de gestión académica

Las instituciones universitarias no son pioneras en tener la mejor proporción posible de mujeres en cargos de gestión académica. Todo lo contrario, en el mundo empresarial se ha avanzado más. Las profesoras universitarias que ocupan cargos de gestión académica permanecen durante más tiempo ocupando cargos dentro de un mismo nivel en la estructura vertical de la organización que sus compañeros y muestran escaso interés por acceder a cargos de nivel superior en la escala jerárquica de la gestión universitaria. El estudio de las razones por las cuáles ocurre esto es el principal objetivo de este artículo. A través de un cuestionario suministrado a 150 profesores y profesoras pertenecientes a cuatro universidades catalanas, cuyos departamentos eran dirigidos por mujeres, así como 18 entrevistas realizadas a personas expertas en temas de gestión, liderazgo y género se obtiene una serie de razones y percepciones sobre las barreras y dificultades que encuentran las mujeres para acceder a cargos académicos en la universidad y ejercerlos. Entre las barreras que impiden a las profesoras universitarias ejercer cargos de gestión encontramos que algunas de tipología interna y otras de tipología externa. Entre las internas se pueden citar las propias de los procesos de socialización: diferencias en la educación de niños y niñas, miedo a defraudar las expectativas del papel femenino, falta de modelos donde mirarse poco interés por el estilo de liderazgo tradicional o baja autoestima. Entre las externas podemos citar la cooptación, la dificultad de conciliación entre vida profesional y familiar, la cultura sexuada de las universidades y los estereotipos ligados al género femenino y el liderazgo.Universities are not pioneering in having the best proportion of women in the academic management positions. All the opposite, business enterprise has moved forward faster. Furthermore, it seems that female professors who have an academic management charge remain during more time occupying charges in the same vertical structure level of the organization than do their male colleagues, showing a scarce interest in accessing to superior charges in the hierarchical scale of the university management. The main objective of this article is to study the reasons by which it happens. Applying a survey to 150 professors of four Catalan Universities, whose departments were leaded by women, and interviewing 18 experts in management, leadership and gender issues, several of the reasons and perceptions about the barriers and difficulties that female professors find in order to accede and develop academic management positions have been obtained. Barriers which make female professors unlikely to access to academic management positions are divided up into two groups: internal and external. Among those of an internal nature, we could mention the internalization of sex-specific behavioral models that correspond to a socialization process based on boy's and girl's differences, the fear of deceiving female role expectations, the absence of female mentors, the scarce interest of women in the traditional way of leadership or their poor self-esteem. Among the external barriers we can include cooptation, difficulties in balancing professional and familiar life, the gendered university culture and stereotypes related to feminine gender and leadership

Las bases de la mejora: la detección del problema y estrategia a aplicar

Publishe

Magnetic and superconducting phase diagrams in ErNi2B2C

We present measurements of the superconducting upper critical field Hc2(T) and the magnetic phase diagram of the superconductor ErNi2B2C made with a scanning tunneling microscope (STM). The magnetic field was applied in the basal plane of the tetragonal crystal structure. We have found large gapless regions in the superconducting phase diagram of ErNi2B2C, extending between different magnetic transitions. A close correlation between magnetic transitions and Hc2(T) is found, showing that superconductivity is strongly linked to magnetism.Comment: 5 pages, 4 figure

La implicación de las profesoras en la gestión universitaria

En este artículo se exponen los principales resultados obtenidos al investigar como ejercen la participación las mujeres en los órganos de gobierno de la universidad. Partiendo de la aplicación de dos estrategias metodológicas, la observación sistemática categorial y la entrevista grupal, se concluye que existen ciertas diferencias de comportamiento entre géneros en las reuniones de toma de decisiones. Además, se constatan otros aspectos relacionados con la calidad de la decisión, con el llamado 'estilo femenino' de participación y con otros factores, además del género, que parecen influir en la forma de gestionar de las profesoras universitariasThis article highlights the main results obtained from research into the manner in which women participate in the university's governing bodies. Starting from the application of two methodological strategies, systematic categoric observation and group-based interview, the article concludes that there are certain behavioural differences between genders in meetings of a decision-taking nature. Furthermore, other aspects are emphasised, relating to decision quality, to the so-called 'feminine mode' of participation as well as to other factors - in addition to gender - which appear to influence women university teachers' style of managemen

Scanning tunneling spectroscopy of layers of superconducting 2H-TaSe2_\textbf{2}: Evidence for a zero bias anomaly in single layers

We report a characterization of surfaces of the dichalcogenide TaSe$_2$ using scanning tunneling microscopy and spectroscopy (STM/S) at 150 mK. When the top layer has the 2H structure and the layer immediately below the 1T structure, we find a singular spatial dependence of the tunneling conductance below 1 K, changing from a zero bias peak on top of Se atoms to a gap in between Se atoms. The zero bias peak is additionally modulated by the commensurate $3a_0 \times 3a_0$ charge density wave of 2H-TaSe$_2$. Multilayers of 2H-TaSe$_2$ show a spatially homogeneous superconducting gap with a critical temperature also of 1 K. We discuss possible origins for the peculiar tunneling conductance in single layers.Comment: 10 pages, 10 figure

Enhancement of long-range correlations in a 2D vortex lattice by an incommensurate 1D disorder potential

arXiv:1410.7782v1Long-range correlations in two-dimensional (2D) systems are significantly altered by disorder potentials. Theory has predicted the existence of disorder-induced phenomena, such as Anderson localization or the emergence of a Bose glass. More recently, it has been shown that when disorder breaks 2D continuous symmetry, long-range correlations can be enhanced. Experimentally, developments in quantum gases have allowed the observation of the effects of competition between interaction and disorder. However, experiments exploring the effect of symmetry-breaking disorder are lacking. Here, we create a 2D vortex lattice at 0.1 K in a superconducting thin film with a well-defined 1D thickness modulation - the symmetry-breaking disorder - and track the field-induced modification using scanning tunnelling microscopy. We find that the 1D modulation becomes incommensurate with the vortex lattice and drives an order-disorder transition, behaving as a scale-invariant disorder potential. We show that the transition occurs in two steps and is mediated by the proliferation of topological defects. The resulting critical exponents determining the loss of positional and orientational order are far above theoretical expectations for scale-invariant disorder and follow instead the critical behaviour describing dislocation unbinding melting. Our data show that randomness disorders a 2D crystal, with enhanced long-range correlations due to the presence of a 1D modulation.This work was supported by the Spanish MINECO (FIS2011-23488, MAT2011-27553-C02, MAT 2012-38318-C03, Consolider Ingenio Molecular Nanoscience CSD2007-00010), the Comunidad de Madrid through program Nanobiomagnet (S2009/MAT-1726) and by the Marie Curie Actions under the project FP7-PEOPLE-2013-CIG-618321 and contract no. FP7-PEOPLE-2010-IEF-273105.Peer Reviewe

Updating the list of known opioids through identification and characterization of the new opioid derivative 3,4-dichloro-N- (2-(diethylamino)cyclohexyl)-N- methylbenzamide (U-49900)

New psychoactive substances have been rapidly growing in popularity in the drug market as non-illegal drugs. In the last few years, an increment has been reported on the use of synthetic alternatives to heroin, the synthetic opioids. Based on the information provided by the European Monitoring Centre for Drug and Drug Addiction, these synthetic opioids have been related to overdoses and deaths in Europe and North America. One of these opioids is the U-47700. A few months ago, U-47700 was scheduled in the U.S. and other countries, and other opioid derivatives have been appearing in order to replace it. One of these compounds is U-49900, an analog of U-47700. A white powder sample was obtained from an anonymous user in Spain. After an accurate characterization by gas chromatography-mass spectrometry, ultra-high performance liquid chromatography-high resolution mass spectrometry, nuclear magnetic resonance and single-crystal X-ray diffraction; and complemented by Fourier-transformed infrared spectroscopy, ultraviolet and circular dichroism spectrophotometry, the drug sample was unequivocally identified as U-49900. The information provided will be useful for the Early Warning System and forensic laboratories for future identifications of the U-49900, as well as in tentative identifications of other related opioids

Scanning microscopies of superconductors at very low temperatures

We discuss basics of scanning tunneling microscopy and spectroscopy (STM/S) of the superconducting state with normal and superconducting tips. We present a new method to measure the local variations in the Andreev reflection amplitude between a superconducting tip and the sample. This method is termed Scanning Andreev Reflection Spectroscopy (SAS). We also briefly discuss vortex imaging with STM/S under an applied current through the sample, and show the vortex lattice as a function of the angle between the magnetic field and sample's surface

1D charge density wave in the hidden order state of URu2Si2

Moir\'e patterns can lead to fundamentally new electronic behavior when formed between two atomic lattices slightly shifted with respect to each other. A solid is however not just characterized by the atomic lattice, but also by charge or magnetic excitations that do not need to be commensurate to the lattice. This raises the question if one can obtain a moir\'e by combining periodic electronic modulations and the atomic lattice. Here we report on the discovery of a one-dimensional charge density wave (1D-CDW) which is a moir\'e pattern between the atomic lattice and a hot spot for electronic scattering in the bandstructure of the hidden order (HO) state of URu$_2$Si$_2$. The moir\'e is produced by fracturing the crystal at low temperatures. Our results suggest that charge interactions are among the most relevant features competing with HO in URu$_2$Si$_2$