Thermodynamic phase diagram of the competition between superconductivity and charge order in cuprates

We argue that there is a special doping point in the phase diagram of cuprates, such that the condensation of holes into a charge-ordered and into a superconducting phase are degenerate in energy but with an energy barrier in between. We present a Monte Carlo simulation of this problem without and with quenched disorder. While in the clean case charge order and superconductivity are separated by a first-order line which is nearly independent of temperature, in the presence of quenched disorder, charge order is fragmented into domains separated by superconducting filaments reminiscent of the supersolid behavior in $^4$He. The resulting phase diagram is in good agreement with the experiments.Comment: 30 pages, 17 figure

Aspectos fundamentales de la suspensión de pagos

La presente tesis está compuesta por ocho capítulos enfocados en dar una visión doctrinaria y jurídica de la institución de la suspensión de pagos, para lo cual y en cuanto al aspecto doctrinario se hizo acopio de varios tratadistas, en donde la bibliografía más precisa y abundante es de autores españoles y mexicanos, mientras que para él aspectos jurídico se utilizó la siguiente legislación salvadoreña: el Código de Comercio, la Ley de Procedimientos Mercantiles en cuanto a su tramitación procesal, así como también el Código de Procedimientos Civiles

Generalized Rashba Electron-Phonon Coupling and Superconductivity in Strontium Titanate

SrTiO3 is known for its proximity to a ferroelectric phase and for showing an 'optimal' doping for superconductivity with a characteristic dome-like behaviour resembling systems close to a quantum critical point. Several mechanisms have been proposed to link these phenomena, but the abundance of undetermined parameters prevents a definite assessment. Here, we use ab initio computations supplemented with a microscopic model to study the linear coupling between conduction electrons and the ferroelectric soft transverse modes allowed in the presence of spin-orbit coupling. We find a robust Rashba-like coupling, which can become surprisingly strong for particular forms of the polar eigenvector. We characterize this sensitivity for general eigenvectors and, for the particular form deduced by hyper-Raman scattering experiments, we find a BCS pairing coupling constant of the right order of magnitude to support superconductivity. The ab initio computations enable us to go beyond the linear-in-momentum conventional Rashba-like interaction and naturally explain the dome behaviour including a characteristic asymmetry. The dome is attributed to a momentum dependent quenching of the angular momentum due to a competition between spin-orbit and hopping energies. The optimum density for having maximum Tc results in rather good agreement with experiments without free parameters. These results make the generalized Rashba dynamic coupling to the ferroelectric soft mode a compelling pairing mechanism to understand bulk superconductivity in doped SrTiO3.Comment: 18 pages, 8 figure

Enhanced Critical Field of Superconductivity at an Oxide Interface

The nature of superconductivity and its interplay with strong spin-orbit coupling at the KTaO3(111) interfaces remains a subject of debate. To address this problem, we grew epitaxial LaMnO3/KTaO3(111) heterostructures. We show that superconductivity is robust against the in-plane magnetic field, with the critical field of superconductivity reaching 25 T in optimally doped heterostructures. The superconducting order parameter is highly sensitive to carrier density. We argue that spin-orbit coupling drives the formation of anomalous quasiparticles with vanishing magnetic moment, providing the condensate significant immunity against magnetic fields beyond the Pauli paramagnetic limit. These results offer design opportunities for superconductors with extreme resilience against magnetic field

Assessment of pavement deflection under vehicle loads using a 3D-DIC system in the field

This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing of pavements and to support the development of techniques for a rapid evaluation of the conservation status of existing roads. Little research was found on this topic. The passage of a car wheel on an asphalt pavement was adopted as a case study. The DIC measurements were compared to those gathered by contact sensors. From a qualitative point of view, the DIC measurements captured the realistic shape of a deflection basin. From a quantitative point of view, the deflection values provided by the DIC system had a mean error of 0.015 mm and a standard deviation of 0.011 mm. At the moment of highest load, these errors had a mean value and standard deviation of − 0.016 mm and 0.021 mm, respectively. Thus, to improve the accuracy of the system, we propose modifying the camera support, speckle pattern, and control of natural lightWe thank Extraco S.A. for allowing us to perform the test on their company facilities. This work was supported by the Strategic Researcher Cluster BioReDes funded by the Xunta de Galicia (Regional Government of Galicia) under project ref. ED431E 2018/09 and by the Xunta de Galicia under the grant “Financial aid for the consolidation and structure of competitive units of investigation in the universities of the University Galician System (2020-22)” under project ref. ED341B 2016/30. This work was also made possible due to the Spanish Agencia Estatal de Investigación (AEI), since Dr. Bastos was contracted in the frame of the postdoctoral grant Juan de la Cierva – Formación (FJC2019-039743-I/AEI/10.13039/501100011033)S