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Swirling spin textures, including topologically nontrivial states, such as skyrmions, chiral domain walls, and magnetic vortices, have garnered significant attention within the scientific community due to their appeal from both fundamental and applied points of view. However, their creation, controlled manipulation, and stability are typically constrained to certain systems with specific crystallographic symmetries, bulk or interface interactions, and/or a precise stacking sequence of materials. Recently, a new approach has shown potential for the imprint of magnetic radial vortices in soft ferromagnetic compounds making use of the stray field of YBa2Cu3O7-delta superconducting microstructures in ferromagnet/superconductor (FM/SC) hybrids at temperatures below the superconducting transition temperature (T-C). Here, we explore the lower size limit for the imprint of magnetic radial vortices in square and disc shaped structures as well as the persistence of these spin textures above T-C, with magnetic domains retaining partial memory. Structures with circular geometry and with FM patterned to smaller radius than the superconductor island facilitate the imprinting of magnetic radial vortices and improve their stability above T-C, in contrast to square structures where the presence of magnetic domains increases the dipolar energy. Micromagnetic modeling coupled with a SC field model reveals that the stabilization mechanism above T-C is mediated by microstructural defects. Superconducting control of swirling spin textures, and their stabilization above the superconducting transition temperature by means of defect engineering holds promising prospects for shaping superconducting spintronics based on magnetic textures, Helmholtz Zentrum Berlin fur Materialen und Energie, European Commission, MInisterio de Economía y Competitividad (España), Agence Nationale de la Recherche (France), Alexander von Humboldt Foundation, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub, Pagado por el autor

EuroConference on Interfaces in Nanostructured Materials (2004. Kloster Irsee, Germany) JUN 06-11, 2004 Zeitschrift fuer Metallkunde/Materials Research and Advanced Techniques, Experimental tests for zirconia/nickel composites determined lower toughness than expected. In this regard, the combination of ab initio density functional theory calculations and high-resolution transmission electron microscopy observations allowed to describe the nature of the zirconia/nickel interface and to justify the absence of any toughening mechanism by grain bridging of the metal particles. In the particular case of nanocomposites, enhanced values of hardness were found. Hardness increases have been justified by a novel model which takes into account the Hall-Petch effect and mean particle size according to the percolation theory. It has been found that this model is not exclusive to zirconia/nickel but can be extended to several other superhard composites., Ministerio de Ciencia y Tecnología (España), Consejo Superior de Investigaciones Cientificas (España), European Social Fund, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, unpub

Rare earth elements (REEs) as Dysprosium (Dy) are critical elements for the fabrication of components in many green energy technologies, from electric vehicles to wind turbines. Consequently, there is an increasing interest in creating sustainable and effective materials for the recovery and recycling of these elements. Zeolite materials have demonstrated a high affinity and selectivity for REEs. Thus, this paper aims to study the use of a synthetic LTA zeolite functionalized with nanomagnetite for Dy absorption, including a complete characterization of the synthetic zeolite, the kinetics and the factors affecting the adsorption efficiency. The maximum adsorption capacity reaches a value around 35 mg of Dy per gram of zeolite. The results from the adsorption isotherms and kinetic study revealed a good agreement with both Langmuir and Temkin models and pseudo-second-order kinetics. Furthermore, the thermodynamic analysis suggests that the adsorption of Dy onto the zeolite is a spontaneous and favorable process. The findings from this work could provide insights into the design and optimization of zeolite-based processes for REE recovery and recycling, contributing to the development of a more sustainable and circular economy., Ministerio para la Transición Ecológica y el Reto Demográfico (MITECO), Comunidad de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Se realiza una revisión detallada de los conceptos de astromineralogía y mineralogía espacial, concretando sus ámbitos actuales de aplicación de acuerdo con su evolución histórica y científica. Se propone que los minerales constituyen los «ladrillos clave» de la materia en el universo; unidades básicas que nos ayudan a entender su funcionamiento a distintas escalas. Se describen los tipos principales de astrominerales y se evalúa la importancia de los minerales presentes en los meteoritos para entender los procesos desarrollados en el sistema solar. Por último, se plantea que la consolidación de la astromineralogía y mineralogía espacial se produce mediante la relación de la geología planetaria, la astrofísica y la astroquímica, sin olvidar el importantísimo papel que juegan las nuevas técnicas espectroscópicas, sobre todo para la realización de análisis de manera remota e «in situ»., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The interplay between ferromagnetism and superconductivity has attracted substantial interest due to its potential for exotic quantum phenomena and advanced electronic devices. Although ferromagnetism and superconductivity are antagonistic phenomena, ferromagnets (F) can host spin-triplet superconductivity induced via proximity with superconductors (S). To date, most of the experimental effort has been focused on single S/F/S junctions. Here, we have found the fingerprints of long-range superconducting proximity effect in micrometric weaklink arrays, formed by embedding YBa2Cu3O7 superconducting islands in a half-metallic ferromagnet La0.7Ca0.3MnO3 film. These arrays show magnetoresistance oscillations that appear at temperatures below the critical temperature of YBa2Cu3O7 for currents below a threshold, indicating their superconducting origin. This realization paves the way for device architectures displaying macroscopic quantum interference effects, which are of interest for field sensing applications, among others., Agencia Estatal de Investigación (España), Ministerio de Ciencia e Innovación (España), Comunidad de Madrid, Helmholtz Zentrum Berlin, European Commission, Agence Nationale de la Recherche (France), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub, Pagado por el autor

Advance Article 20 Jul 2024 NT-09-618999 DIMAG project from 2019 FLAG-ERA call CT82/20–CT83/ 20 1/ SOL/2021/2 FI2023-2-0022 FI-2023-1-0016, The basal plane of MoS2 has been considered a potential source of active catalytic sites in hydrogen absorption. Sulfur vacancies can activate the inert basal plane of MoS2; however, achieving sufficient catalytic efficiency requires a high defect concentration of about 12%. We investigated the effect of defects on the hydrogen adsorption on the basal plane of MoS2 using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations. Mild annealing in terms of temperature and time effectively introduces single sulfur vacancy (VS) defects, as observed from the electronic structural changes that are in excellent agreement with DFT calculations for a VS concentration of ∼4%. Subsequent exposure to molecular hydrogen showed that the higher hydrogen pressure facilitates hydrogen adsorption, as predicted by theoretical calculations. Interestingly, hydrogen exposure restores the electronic structure to a state similar to that of pristine MoS2. These results suggest that the controlled introduction of VS defects via annealing is a promising strategy for enhancing hydrogen adsorption on MoS2, paving the way for its potential use in future catalytic applications., Ministerio de Ciencia e Innovación (España), Comunidad de Madrid, Agence Nationale de la Recherche (France), Universidad Complutense de Madrid, Banco de Santander, Ministry of Science and Higher Education (Poland), Red Española de Supercomputación, Ministerio de Ciencia, Innovación y Universidades (España), Depto. de Física de Materiales, Fac. de Ciencias Físicas, Instituto de Magnetismo Aplicado (IMA), TRUE, pub

2023 Descuentos MDPI, The aim of this study is to prove that resistive heating enables the synthesis of metal/metal oxide composites in the form of core-shell structures. The thickness and morphology of the oxide layer depends strongly on the nature of the metal, but the influences of parameters such as the time and current profiles and the presence of an external field have also been investigated. The systems chosen for the present study are Zn/ZnO, Ti/TiO2, and Ni/NiO. The characterization of the samples was performed using techniques based on scanning electron microscopy (SEM). The thicknesses of the oxide layers varied from 10 mu m (Zn/ZnO) to 50 mu m (Ni/NiO). In the case of Zn- and Ti-based composites, the growth of nanostructures on the oxide layer was observed. Micro- and nanoneedles formed on the ZnO layer while prism-like structures appeared on the TiO2. In the case of the NiO layer, micro- and nanocrystals were observed. Applying an external electric field seemed to align the ZnO needles, whereas its effect on TiO2 and NiO was less appreciable, principally affecting the shape of their grain boundaries. The chemical compositions were analysed using X-ray spectroscopy (EDX), which confirmed the existence of an oxide layer. Structural information was obtained by means of X-ray diffraction (XRD) and was later checked using Raman spectroscopy. The oxide layers seemed to be crystalline and, although some non-stoichiometric phases appeared, the stoichiometric phases were predominant; these were wurtzite, rutile, and cubic for Zn, Ti, and Ni oxides, respectively. The photoluminescence technique was used to study the distribution of defects on the shell, and mainly visible bands (2-2.5 eV), attributed to oxygen vacancies, were present. The near-band edges of ZnO and TiO2 were also observed around 3.2-3.3 eV., Comunidad de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Review 2023 Descuentos MDPI, Four decades have elapsed since the first quasiperiodic crystal was discovered in the Al-Mn alloy system, and much progress has been made during this time on the science of quasicrystals (QCs). Notwithstanding this, a significant number of open questions still remain regarding both fundamental and technological aspects. For instance: What are QCs good for? How can we improve the current provisional QC definition? What is the role of the underlying quasiperiodic order and the characteristic inflation symmetry of these compounds in the emergence of their unusual physicochemical properties? What is the nature of chemical bonding in QCs formed in different sorts of materials such as alloys, oxides, or organic polymers? Herein these and other closely related issues are discussed from an interdisciplinary perspective as well as prospective future work in the field in the years to come., Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Event: SPIE Optical Engineering + Applications, 2009, San Diego, California, United States. © (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE)., Many applications involve the use of a compound parabolic concentrator (CPC) like, natural lighting, thermal applications, optics for illuminators, optical fibre coupling and solar energy. The use of a CPC in reverse mode for natural lighting gives the chance to use it as a lighting skylight in ceilings because light output is controlled inside the design angle, on the contrary having a low flux transfer ratio because of the reduced area of the entrance pupil regarding exit pupil. The authors propose an innovative 3D hollow prismatic CPC (HPCPC) made of a dielectric material, which has a high efficiency comparing it with aluminium CPC. The basic idea is to use a hollow prismatic light guide with CPC shape. This paper reports 2D, 3D design and numerical analysis by raytracing software, also experimental results are shown. The system works almost like a true CPC when light enters through standard entrance pupil and also collect light that enters outside entrance pupil. Performance and efficiency of the prismatic CPC is in average 300% higher than standard aluminium CPC for collimated light in a range from 0º to 85º. A prototype has been developed and tested., Depto. de Óptica, Fac. de Óptica y Optometría, TRUE, pub

El texto completo de este trabajo no se encuentra disponible por no haber sido facilitado aún por su autor, por restricciones de copyright, o por no existir una versión digital, Superconductivity can be induced in a normal material via the ‘leakage’ of superconducting pairs of charge carriers from an adjacent superconductor. This so-called proximity e ect is markedly influenced by graphene’s unique electronic structure, both in fundamental and technologically relevant ways. These include an unconventional form1,2 of the ‘leakage’ mechanism— the Andreev reflection3—and the potential of supercurrent modulation through electrical gating4 . Despite the interest of high-temperature superconductors in that context5,6 , realizations have been exclusively based on low-temperature ones. Here we demonstrate a gate-tunable, high-temperature superconducting proximity e ect in graphene. Notably, gating e ects result from the perfect transmission of superconducting pairs across an energy barrier—a form of Klein tunnelling7,8 , up to now observed only for non-superconducting carriers9,10— and quantum interferences controlled by graphene doping. Interestingly, we find that this type of interference becomes dominant without the need of ultraclean graphene, in stark contrast to the case of low-temperature superconductors11. These results pave the way to a new class of tunable, high-temperature Josephson devices based on large-scale graphene., Agence Nationale de la Recherche (ANR), EU Work Programme, European Union (EU) Marie Curie Actions, UK Research & Innovation (UKRI), Engineering & Physical Sciences Research Council (EPSRC), Institut Universitaire de France, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

2023 Descuentos MDPI, Emission Fe-57 Mossbauer spectroscopy (eMS), following the implantation of radioactive Mn-57(+) ions, has been used to study the temperature dependence of the hyperfine magnetic field at Fe sites in Ba-doped BiFeO3 (BFO) thin films. 57Mn fi decays (t(1/ 2) = 90 s) to the 14.4 keV Mossbauer state of Fe-57, thus allowing online eMS measurements at a selection of sample temperatures during Mn implantation. The eMS measurements were performed on two thin film BFO samples, 88 nm and 300 nm thick, and doped to 15% with Ba ions. The samples were prepared by pulsed laser deposition on SrTiO_3 substrates. X-ray diffraction analyses of the samples showed that the films grew in a tetragonal distorted structure. The Mossbauer spectra of the two films, measured at absorber temperatures in the range 301 K-700 K, comprised a central pair of paramagnetic doublets and a magnetic sextet feature in the wings. The magnetic component was resolved into (i) a component attributed to hyperfine interactions at Fe^(3+) ions located in octahedral sites (B_(hf)); and (ii) to Fe^(3+) ions in implantation induced lattice defects, which were characterized by a distribution of the magnetic field B_(Distr). The hyperfine magnetic field at the Fe probes in the octahedral site has a room temperature value of B_(hf) = 44.5(9) T. At higher sample temperatures, the Bhf becomes much weaker, with the Fe3+ hyperfine magnetic contribution disappearing above 700 K. Simultaneous analysis of the Ba-BFO eMS spectra shows that the variation of the hyperfine field with temperature follows the Brillouin curve for S = 5/2., Federal Ministry of Education and Research (German), Unión Europea. H2020, Ministerio de Economía y Competitividad (España), Banco de Santander, Universidad Complutense de Madrid, Austrian Science Fund, Icelandic University Research Fund, National Research Foundation (South Africa), Fondo Europeo de Desarrollo Regional, Gobierno Vasco, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

El texto completo de este trabajo no se encuentra disponible por no haber sido facilitado aún por su autor, por restricciones de copyright, o por no existir una versión digital, An unusual conducting surface state can be produced in SrTiO3 substrates by irradiation with Argon ions from a plasma source, at low energy and high doses. The effects of irradiation are analyzed here by atomic force microscopy (AFM) and aberration corrected scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). Depth sensitive studies demonstrate the existence of a heavily damaged surface layer and an oxygen vacancy rich layer immediately underneath, both induced during the irradiation process. We find a clear dependence of the Ti oxidation state with the depth, with a very intense Ti3+ component near the surface. Oxygen vacancies act as n-type doping by releasing electrons into the lattice and producing an insulator-to-metal transition, which explains the unusual metallic behavior of these samples., Materials Sciences and Engineering Division of the US Department of Energy (DOE), ORNL’s Shared Research Equipment (ShaRE) User Program, ERC starting Investigator Award, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Acquiring the temperature of a single living cell is not a trivial task. In this paper, we devise a novel nanothermometer, capable of accurately determining the temperature of solutions as well as biological systems such as HeLa cancer cells. The nanothermometer is based on the temperature-sensitive fluorescence of NaYF4:Er3+,Yb3+ nanoparticles, where the intensity ratio of the green fluorescence bands of the Er3+ dopant ions (H-2(11/2) -> I-4(15/2) and S-4(3/2) -> I-4(15/2)) changes with temperature. The nanothermometers were first used to obtain thermal profiles created when heating a colloidal solution of NaYF4:Er3+,Yb3+ nanoparticles in water using a pump-probe experiment. Following incubation of the nanoparticles with HeLa cervical cancer cells and their subsequent uptake, the fluorescent nanothermometers measured the internal temperature of the living cell from 25 degrees C to its thermally induced death at 45 degrees C., Universidad Autonoma de Madrid, Banco Santander-CEAL-UAM, Natural Sciences and Engineering Research Council of Canada (NSERC), Gouvernement du Quebec, Ministere du Developpement economique, de l'Innovation et de l'Exportation, Comunidad de Madrid, Ministerio de Educación y Ciencia (España), Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Transient homogeneous nucleation is studied in the limit of large critical sizes. Starting from pure monomers, three eras of transient nucleation are characterized in the classic Becker-Döring kinetic equations with two different models of discrete diffusivity: the classic Turnbull-Fisher formula and an expression describing thermally driven growth of the nucleus. The latter diffusivity yields time lags for nucleation which are much closer to values measured in experiments with disilicate glasses. After an initial stage in which the number of monomers decreases, many clusters of small size are produced and a continuous size distribution is created. During the second era, nucleii are increasing steadily in size in such a way that their distribution appears as a wave front advancing towards the critical size for steady nucleation. The nucleation rate at critical size is negligible during this era. After the wave front reaches critical size, it ignites the creation of supercritical clusters at a rate that increases monotonically until its steady value is reached. Analytical formulas for the transient nucleation rate and the time lag are obtained that improve classical ones and compare very well with direct numerical solutions., Unión Europea, Ministerio de Ciencia y Tecnología, Depto. de Análisis Matemático y Matemática Aplicada, Fac. de Ciencias Matemáticas, TRUE, pub

2023 Otros acuerdos transformativos de la UCM, Oxide-based 2D electron gases (2DEGs) have generated significant interest due to their potential for discovering novel physical properties. Among these, 2DEGs formed in KTaO_3 stand out due to the recently discovered crystal face-dependent superconductivity and large Rashba splitting, both of which hold potential for future oxide electronics devices. In this work, angle-resolved photoemission spectroscopy is used to study the electronic structure of the 2DEG formed at the (110) surface of KTaO_3 after deposition of a thin Al layer. The experiments reveal a remarkable anisotropy in the orbital character of the electron-like dispersive bands, which form a Fermi surface consisting of two elliptical contours with their major axes perpendicular to each other. The measured electronic structure is used to constrain the modeling parameters of self-consistent tight-binding slab calculations of the band structure. In these calculations, an anisotropic Rashba splitting is found with a value as large as 4 meV at the Fermi level along the [−110] crystallographic direction. This large unconventional and anisotropic Rashba splitting is rationalized based on the orbital angular momentum formulation. These findings provide insights into the interpretation of spin-orbitronics experiments and help to constrain models for superconductivity in the KTO(110)-2DEG system., Comunidad de Madrid, Ministerio de Ciencia e Innovación (España), Agencia Estatal de Investigación (España), Fondo Europeo de Desarrollo Regional (Unión Europea), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Electrodeposited nanowires are an excellent scenario to study and control magnetic domain wall motion in nanostructures. In particular, the introduction of local changes in composition during the growth procedure has been proven to be very efficient for controlling the magnetization dynamics. In this work, we show the possibility of introducing compositional gradients in FeNi electrodeposited nanowires by gradually changing the Fe/Ni ratio along their axis. These compositional gradients produce an asymmetrical landscape for domain wall motion which is reflected in asymmetrical magnetization processes under an applied magnetic field. By studying nanowires with different compositional gradients we were able to correlate composition and magnetic asymmetry. Our results pave the way towards full control of the movement of domain walls along the nanowires., Agencia Estatal de Investigación, Comunidad de Madrid, Unión Europea, Fundación Alexander von Humboldt, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

The full rare-earth (RE) chromites series (RE)CrO3 with an orthorhombic distorted (Pnma) perovskite structure and the isostructural compound YCrO3 can be synthesized through a simple microwave-assisted technique, yielding high-quality materials. Magnetization measurements evidence that the Néel temperature for antiferromagnetic Cr3+–Cr3+ ordering strongly depends on the RE3+ ionic radius (IOR), and a rich variety of different magnetic spin interactions exists. Dielectric spectroscopy on sintered pellets indicates electronic inhomogeneity in all samples as manifested by the presence of at least two dielectric relaxation processes associated with grain boundary and grain interior bulk contributions. X-ray diffraction, Raman spectroscopy, and temperature-dependent dielectric permittivity data do not indicate potential noncentrosymmetry in the crystal or concomitant ferroelectricity. Strong correlations between the magnetic and dielectric properties were not encountered, and microwave-synthesized (RE)CrO3 may not be classified as magnetoelectric or multiferroic materials., Comunidad de Madrid, MICINN, MICINN, Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

2023 Descuentos MDPI, This study focuses on the fabrication of polymer nanocomposite films using polyvinyl alcohol (PVA)/graphene quantum dots (GQDs). We investigate the relationship between the structural, thermal, and nanoscale morphological properties of these films and their photoluminescent response. Although according to X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and differential thermal analysis (DTA), the incorporation of GQDs does not significantly affect the percentage crystallinity of the PVA matrix, for a range of added GQD concentrations, atomic force microscopy (AFM) showed the formation of islands with apparent crystalline morphology on the surface of the PVA/GQD films. This observation suggests that GQDs presumably act as nucleating agents for island growth. The incorporation of GQDs also led to the formation of characteristic surface pores with increased stiffness and frictional contrast, as indicated by ultrasonic force microscopy (UFM) and frictional force microscopy (FFM) data. The photoluminescence (PL) spectra of the films were found to depend both on the amount of GQDs incorporated and on the film morphology. For GQD loads >1.2%wt, a GQD-related band was observed at similar to 1650 cm(-1) in FT-IR, along with an increase in the PL band at lower energy. For a load of similar to 2%wt GQDs, the surface morphology was characterized by extended cluster aggregates with lower stiffness and friction than the surrounding matrix, and the PL signal decreased., Universidad de Castilla La Mancha, Fondo Europeo de Desarrollo Regional (Unión Europea), Ministerio de Ciencia e Innovación (España), Unión Europea, Comunidad de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Electron microscopy has revealed time-resolved glide and climb motion of dislocations in graphene and imaged their strain and rotation fields., Depto. de Análisis Matemático y Matemática Aplicada, Fac. de Ciencias Matemáticas, TRUE, pub

We propose a model of ripples in suspended graphene sheets based on plate equations that are made discrete with the periodicity of the honeycomb lattice and then periodized. In addition, the equation for the displacements with respect to the planar configuration contains a double-well site potential, a nonlinear friction, and a multiplicative white-noise term satisfying the fluctuation-dissipation theorem. The nonlinear friction terms agree with those proposed by Eichler et al.[Nature Nanotech. 6, 339 (2011)] to explain their experiments with a graphene resonator. The site double-well potential indicates that the carbon atoms at each lattice point have equal probability to move upward or downward off plane. For the considered parameter values, the relaxation time due to friction is much larger than the periods of membrane vibrations and the noise is quite small. Then ripples with no preferred orientation appear as long-lived metastable states for any temperature. Numerical solutions confirm this picture., Ministerio de Economía y Competitividad, Depto. de Análisis Matemático y Matemática Aplicada, Fac. de Ciencias Matemáticas, TRUE, pub

Defective few-layered graphene mesostructures (DFLGMs) are produced from graphite flakes by high-energy milling processes. We obtain an accurate control of the generated mesostructures, as well as of the amount and classification of the structural defects formed, providing a functional material for microwave absorption purposes. Working under far-field conditions, competitive values of minimum reflection loss coefficient (RL_(min)) = −21.76 dB and EAB = 4.77 dB are achieved when DFLGMs are immersed in paints at a low volume fraction (1.95%). One step forward is developed by combining them with the excellent absorption behavior that offers amorphous Fe_(73.5)Si_(13.5)B_(9)Cu_(1)Nb microwires (MWs), varying their filling contents, which are below 3%. We obtain a RLmin improvement of 47% (−53.08 dB) and an EAB enhancement of 137% (4 dB) compared to those obtained by MW-based paints. Furthermore, a f_(min) tunability is demonstrated, maintaining similar RL_(min) and EAB values, irrespective of an ideal matching thickness. In this scenario, the Maxwell-Garnet standard model is valid, and dielectric losses mainly come from multiple reflections, interfacial and dielectric polarizations, which greatly boost the microwave attenuation of MWs. The present concept can remarkably enhance not only the MW attenuation but can also apply to other microwave absorption architectures of technological interest by adding low quantities of DFLGMs., Ministerio de Ciencia e Innovación (España), Ministerio de Asuntos Economicos y Transformacion Digital (España), Comunidad de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, Instituto de Magnetismo Aplicado (IMA), TRUE, pub

©2023 By the author(s) Licensee MDPI This research was funded by the Ministerio de Ciencia e Innovación (MCINN), grant number PID2021-123112OB-C21, and Comunidad Autónoma de Madrid by S2018/NMT-4321 NANOMAGCOST. The authors also acknowledge the Sistema Nacional de Garantía Juvenil through the Comunidad Autónoma de Madrid for providing a pre-doctoral contract, PEJ-2020-AI/IND-17711., A systematic study on laser-induced heating carried out in two biological windows (800 nm and 1053 nm) for Fe_(3)O_(4) nanoparticles in water suspension showed evidence of the strong dependence of the specific absorption rate (SAR) on extrinsic parameters such as the vessel volume or laser spot size. The results show that a minimum of 100 mu L must be used in order to obtain vessel-size-independent SARs. In addition, at a constant intensity but different laser powers and spot size ratios, the SARs can differ by a three-fold factor, showing that the laser power and irradiated area strongly affect the heating curves for both wavelengths. The infrared molecular absorber IRA 980B was characterized under the same experimental conditions, and the results confirm the universality of the SARs' dependence on these extrinsic parameters. Based on these results, we propose using solutions of IRA 980B as a standard probe for SAR measurements and employing the ratio SAR(iron oxide)/SAR(IRA 980B) to compare different measurements performed in different laboratories. This measurement standardization allows us to extract more accurate information about the heating performance of different nanoparticles., Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Depto. de Física de Materiales, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2023 by the authors. Licensee MDPI This work was supported by MICINN projects (RTI2018-097195-B-I00, RTI2018-096918-B-C41, PID2021-122562NB-I00 and PID2021-123190OB-I00/AEI/10.13039/501100011033/FEDER, UE). The authors acknowledge the financial support of the excellence research network RED2018-102609-T by MINECO. The authors acknowledge the support from the Air Force Office of Scientific Research under Award No. FA8655-20-1-7013 (Program Manager: Ali Sayir). M.A.-O. acknowledges financial support from MICINN (FPU contract No. FPU15/01982) and thanks the Central Research Development Fund (CRDF) of the University of Bremen for funding (ZF04/2021). J.S.M. and J.J. were supported by the Air Force Office of Scientific Research under award number FA9550-21-1-0507, monitored by Dr. Ali Sayir. Any opinions, finding, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the United States Air Force., An accurate knowledge of the optical properties of beta-Ga_(2)O_(3) is key to developing the full potential of this oxide for photonics applications. In particular, the dependence of these properties on temperature is still being studied. Optical micro- and nanocavities are promising for a wide range of applications. They can be created within microwires and nanowires via distributed Bragg reflectors (DBR), i.e., periodic patterns of the refractive index in dielectric materials, acting as tunable mirrors. In this work, the effect of temperature on the anisotropic refractive index of beta-Ga_(2)O_(3) n(lambda,T) was analyzed with ellipsometry in a bulk crystal, and temperature-dependent dispersion relations were obtained, with them being fitted to Sellmeier formalism in the visible range. Micro-photoluminescence (mu-PL) spectroscopy of microcavities that developed within Cr-doped beta-Ga_(2)O_(3) nanowires shows the characteristic thermal shift of red-infrared Fabry-Perot optical resonances when excited with different laser powers. The origin of this shift is mainly related to the variation in the temperature of the refractive index. A comparison of these two experimental results was performed by finite-difference time-domain (FDTD) simulations, considering the exact morphology of the wires and the temperature-dependent, anisotropic refractive index. The shifts caused by temperature variations observed by mu-PL are similar, though slightly larger than those obtained with FDTD when implementing the n(lambda,T) obtained with ellipsometry. The thermo-optic coefficient was calculated., Ministerio de Ciencia e Innovación (MICINN) / FEDER, Ministerio de Ciencia e Innovación (MICINN), Universidad de Bremen, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2023 The Author(s). Published by Elsevier Ltd. We thank Gloria Platero for generously sharing her computational resources and Sergio Bravo for helpful discussions. We also thank the Centro de Supercomputación de Galicia, CESGA, (www.cesga.es, Santiago de Compostela, Spain) for providing access to their supercomputing facilities. This work was supported by grant PID2019-106820RB-C21 funded by MCIN/AEI/ 10.13039/501100011033/ and by ‘‘ERDF A way of making Europe’’, by grant TED2021-129457B-I0 funded by MCIN/AEI/10.13039/501100011033/ and by the ‘‘European Union NextGenerationEU/PRTR’’ and by grant PRE2019-088874 funded by MCIN/AEI/10.13039/501100011033 and by ‘‘ESF Investing in your future’’. ESM acknowledges financial support from FONDECYT Regular, Chile 1221301, and LC gratefully acknowledges the support from Comunidad de Madrid (Spain) under the Multiannual Agreement with Universidad Complutense de Madrid, Program of Excellence of University Professors, in the context of the V Plan Regional de Investigación Científica e Innovación Tecnológica (PRICIT)., We report the existence of moiré patterns and magic angle physics in all families of chiral collapsed carbon nanotubes. A detailed study of the electronic structure of all types of chiral nanotubes, previously collapsed via molecular dynamics, has been performed. We find that each family possesses a unique geometry and moire disposition, as well as a characteristic number of flat bands. Remarkably, all kinds of nanotubes behave the same with respect to magic angle tuning, showing a monotonic behavior that gives rise to magic angles in full agreement with those of twisted bilayer graphene. Therefore, magic angle behavior is universally found in chiral collapsed nanotubes with a small chiral angle, giving rise to moiré patterns. Our approach comprises first-principles and semi-empirical calculations of the band structure, density of states and spatial distribution of the localized states signaled by flat bands., Ministerio de Ciencia e Innovación (MICINN) / NextGenerationEU, Ministerio de Ciencia e Innovación (MICINN) / FSE, Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid / Universidad Complutense (UCM), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2023 by the authors. Licensee MDPI This research was funded by the Tunisian Ministry of Higher Education and Scientific Research and by the Ministerio de Ciencia e Innovación (MCINN), grant number PID2021-123112OBC21., We have investigated the structural, magnetic, and electrical transport properties of Pr_(0.7)Sr_(0.3)Mn_(1-x)Co_(x) O_(3) nanopowders (x = 0, 0.05, 0.10 and 0.15). The Pechini Sol-gel method was used to synthesize these nanopowders. X-ray diffraction at room temperature shows that all the nano powders have an orthorhombic structure of Pnma space group crystallography. The average crystallite size of samples x = 0, 0.05, 0.10, and 0.15 are 33.78 nm, 29 nm, 33.61 nm, and 24.27 nm, respectively. Semi-quantitative chemical analysis by energy dispersive spectroscopy (EDS) confirms the expected stoichiometry of the sample. Magnetic measurements indicate that all samples show a ferromagnetic (FM) to paramagnetic (PM) transition with increasing temperature. The Curie temperature T-C gradually decreases (300 K, 270 K, 250 K, and 235 K for x = 0, 0.05, 0.10, and 0.15, respectively) with increasing Co concentrations. The M-H curves for all compounds reveal the PM behavior at 300 K, while the FM behavior characterizes the magnetic hysteresis at low temperature (5 K). The electrical resistivity measurements show that all compounds exhibit metallic behavior at low temperature (T < T rho) well fitted by the relation rho = rho_(0) + rho_(2)T^(2) + rho_(4.5) T^(4.5) and semiconductor behavior above T rho (T > T rho), for which the electronic transport can be explained by the variable range hopping model and the adiabatic small polaron hopping model. All samples have significant magnetoresistance (MR) values, even at room temperature. This presented research provides an innovative and practical approach to develop materials in several technological areas, such as ultra-high density magnetic recording and magneto resistive sensors., Ministerio de Ciencia e Innovación (MICINN), Tunisian Ministry of Higher Education and Scientific Research, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2022 by the authors. Licensee MDPI This research was funded by the Ministerio de Ciencia e Innovacion (MCIN/AEI/10.13039/501100011033) through grant numbers PID2021-122477OB-I00 and TED2021-129254B-C22, by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior-Brazil (CAPES) under grant number 88887.603800/2021-00, and by the Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS) (21/2551-0000695-1)., Among chalcogenide thermoelectric materials, SnTe is an excellent candidate for intermediate temperature applications, in replacement of toxic PbTe. We have prepared pure polycrystalline SnTe by arc melting, and investigated the structural evolution by temperature-dependent neutron powder diffraction (NPD) from room temperature up to 973 K. In this temperature range, the sample is cubic (space group Fm-3m) and shows considerably larger displacement parameters for Te than for Sn. The structural analysis allowed the determination of the Debye model parameters and provided information on the Sn-Te chemical bonds. SEM images show a conspicuous nanostructuration in layers below 30 nm thick, which contributes to the reduction of the thermal conductivity down to 2.5 W/m center dot K at 800 K. The SPS treatment seems to reduce the number of Sn vacancies, thus diminishing the carrier density and increasing the Seebeck coefficient, which reaches 60 mu V K^(-1) at 700 K, as well as the weighted mobility, almost doubled compared with that of the as-grown sample., Ministerio de Ciencia e Innovación (MICINN) / AEI, Ministerio de Ciencia e Innovación (MICINN)/NextGenerationEU, Ministerio de Ciencia e Innovación (MICINN)/FSE, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Received 19 October 2022, Revised 11 December 2022, Accepted 27 December 2022, Available online 13 January 2023, Version of Record 13 January 2023, The aim is to provide an assessment of radiation damage in coated films on refractive substrates that could be used as relevant information to protect the field lenses in optical diagnostics for ITER. Radiation-resistant optical materials with transparent properties should transfer light from plasma to detectors through the interspace until the port cell area where they are located (more than 10 m from the vacuum window). These optical coatings and substrates should have resilience enough to withstand neutron and gamma irradiation without significant degradation of their transmittance. Coated sapphire (Al2O3 windows), YAG with Broad Band Anti-Reflective (BBAR) and substrates of BaF2/CaF2 protected with anti-humidity coating (Parylene-C) were extensively tested. After testing, transmission mea- surements and analysis of optical surfaces yield significant discoveries. All substrates showed good refractive performance under gamma radiation. On the contrary, Parylene-C did not resist temperatures above 100 degrees Celsius as expected, according to manufacturing specifications. In addition, it was observed that with an energy dose of 332 kGy of gamma rays and a significantly lower temperature of 50 degrees Celsius, the Parylene-C protection is also damaged. Coated sapphire had the best overall performance with respect to the neutron irradiation tests. Nevertheless, the decrease in transmission observed in the YAG and BaF2 coated samples is not significant for the expected cumulative neutron dose that these samples will receive at their location within the diagnostic. This information was considered for the selection of the best candidates as refractive lenses and optical coatings for the Preliminary Design Review (PDR) of ex-vessel components that will integrate the Wide-Angle Viewing System (WAVS) for ITER Equatorial Port 12., Fusion for Energy, Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, pub

© 2023 The Author(s). Work supported by Spanish AEI through Grant PID2020-118078RB-I00 and by Regional Government of Madrid CAM through SINERGICO Project Y2020/NMT-6661 CAIRO-CM. Work at CNRS/Thales lab supported by ERC Grant No. 647100 SUSPINTRONICS', French ANR Grant ANR-15-CE24-0008-01 SUPERTRONICS' and COST action Nanocohybri'. We acknowledge funding from Flag ERA ERA-NET To2Dox Project. J E V thanks C Ulysse and L Vila for collaboration in related projects., The proximity effect between superconductors and ferromagnets may become long range due to the generation of triplet pairs. The recent finding of a long, one micron-range unconventional Josephson effect between YBa_2Cu_3O_7 high Tc cuprates separated by a half metallic La_0.7Sr_0.3MnO_3 manganite ferromagnet has uncovered a novel unconventional triplet proximity effect. In this paper, we examine the temperature dependence of the critical current in planar Josephson junctions. We find that the critical current-normal resistance product follows the predictions of traditional superconductor-normal metal-superconductor junctions, which implies that triplet pairs in a ferromagnet are transported in the diffusive limit similarly to singlet pairs in a normal metal. This result calls for theoretical studies of the new triplet Josephson effect and underlines its potential in future superconducting spintronics., Unión Europea. H2020, Ministerio de Ciencia, Innovación (MICINN), Comunidad de Madrid, Agence nationale de la recherche (ANR), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2023 by the authors. Licensee MDPI, This work was supported by MICINN projects (RTI2018-097195-B-I00, PIE 2021-60-E-030, PIE 2010-6-OE-013 and PID2021-122562NB-I00). B.R. acknowledges financial support from MICINN (contract No. PRE2019-088162)., Polymorphous WO_(3) micro- and nanostructures have been synthesized by the controlled Joule heating of tungsten wires under ambient conditions in a few seconds. The growth on the wire surface is assisted by the electromigration process and it is further enhanced by the application of an external electric field through a pair of biased parallel copper plates. In this case, a high amount of WO_(3) material is also deposited on the copper electrodes, consisting of a few cm^(2) area. The temperature measurements of the W wire agrees with the values calculated by a finite element model, which has allowed us to establish the threshold density current to trigger the WO_(3) growth. The structural characterization of the produced microstructures accounts for the gamma-WO_(3) (monoclinic I), which is the common stable phase at room temperature, along with low temperature phases, known as delta-WO_(3) (triclinic) on structures formed on the wire surface and e-WO_(3) (monoclinic II) on material deposited on external electrodes. These phases allow for a high oxygen vacancies concentration, which is interesting in photocatalysis and sensing applications. The results could help to design experiments to produce oxide nanomaterials from other metal wires by this resistive heating method with scaling-up potential., Ministerio de Ciencia e Innovación (MICINN) / FEDER, Ministerio de Ciencia e Innovación (MICINN) / FSE, Ministerio de Ciencia e Innovación (MICINN), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

2023 Descuento MDPI, Chitosan (CS) composite membranes were prepared using different biocompatible metal oxide nanoparticles (NPs): titanium dioxide (TiO2); iron oxide (Fe3O4); and aluminum oxide (Al2O3). For each nanoparticle, the CS-based composite membranes were prepared with two NPs contents in the CS solution, high (H) and low (L) NPs concentrations. To establish both concentrations, the NPs saturation point in the CS polymeric matrix was determined. The influence of NP concentrations on the physicochemical properties of the CS films was assessed. The prepared CS membranes were characterized with different techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and zeta potential. It was found that the addition of NPs in the CS matrix improved both swelling and mechanical properties. Nanocomposite CS membranes could be prepared using Al2O3 NPs. Swelling experiments revealed different pH-sensitive mechanisms, which might be beneficial in biomedical applications since solute permeation through CS-based composite membranes could be controlled by adjusting environmental conditions. When aspirin transport (ASA) through the prepared membranes was carried out in different release media, SGF (simulating gastric fluid) and SIF (simulating intestinal fluid without enzymes), it was observed that the Fickian diffusion coefficient (D) was conditioned by the pH of the release solution. In SGIT (simulating gastrointestinal transit) medium, a transition time (ttrans) was detected due to the shrinkage of the CS polymeric chains, and the drug release depended not only on the Fickian’s diffusion but also on the shrinkage of the biopolymer, obeying Peppas and Sahlin equation., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub, Descuento UCM

El texto completo de este trabajo no se encuentra disponible por no haber sido facilitado aún por su autor, por restricciones de copyright, o por no existir una versión digital, Novel transparent semiconducting oxides have emerged as key materials for a variety of optoelectronic applications due to their ultra-wide band gap. Owing to the critical role of native defects and impurities in the optoelectronical properties, investigation in detail of the electronic structure of these oxides has become a challenge, being luminescence technique a powerful way to gain insight into the electronic levels. Here, the photoluminescence temperature dependence of Li doped Zn2GeO4 microrods is analysed and discussed in the framework of the electronic levels structure related to native defects and Li impurities. Unlike the undoped material, the blue emission (2.8 eV) of Li-doped germanate exhibits a negative thermal quenching as its photoluminescence intensity increases with increasing temperature. The mechanisms underlying this anomalous behaviour are discussed with the aid of X-ray photoemission spectroscopy and first principles calculations. This study has helped us to understand the role of Li in the electronic structure and optical response of Zn2GeO4. Our results highlight the versatility of Zn2GeO4 luminescence through Li doping, which could be exploited in optoelectronic devices with bespoke properties., Ministerio de Ciencia e Innovación (España), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2022 by the authors. Licensee MDPI We thank the Spanish Ministry of Science and Innovation for granting the project numbers: PID2021-122477OB-I00, TED2021-129254B-C22, and PRE2018-083398, funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, by the “European Union”. Grants PIE: 2021-60-E-030 and PIE: 2010-6-OE-013 are also acknowledged., In this work, Gd-filled skutterudite Gd_(x)Co_(4)Sb_(12) was prepared using one step method under high pressure in a piston-cylinder-based press at 3.5 GPa and moderate temperature of 800 degrees C. A detailed structural characterization was performed using synchrotron X-ray diffraction (SXRD), revealing a filling fraction of x = 0.033(2) and an average bond length of 3.3499(3) angstrom. The lattice thermal expansion accessed via temperature-dependent SXRD led to a precise determination of a Debye temperature of 322(3) K, from the fitting of the unit-cell volume expansion using the second order Gruneisen approximation. This parameter, when evaluated through the mean square displacements of Co and Sb, displayed a value of 265(2) K, meaning that the application of the harmonic Debye theory underestimates the Debye temperature in skutterudites. Regarding the Gd atom, its intrinsic disorder value was similar to 5x and similar to 25x higher than those of the Co and Sb, respectively, denoting that Gd has a strong rattling behavior with an Einstein temperature of theta(E) = 67(2) K. As a result, an ultra-low thermal conductivity of 0.89 W/m center dot K at 773 K was obtained, leading to a thermoelectric efficiency zT of 0.5 at 673 K., Ministerio de Ciencia e Innovación (MICINN) /FEDER, Ministerio de Ciencia e Innovación (MICINN) /NextGenerationEU, Ministerio de Ciencia e Innovación (MICINN) /FSE, Ministerio de Ciencia e Innovación (MICINN), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

2023 Acuerdos transformativos CRUE, Temperature plays a critical role in regulating body mechanisms and indicating inflammatory processes. Local temperature increments above 42 °C are shown to kill cancer cells in tumorous tissue, leading to the development of nanoparticle-mediated thermo-therapeutic strategies for fighting oncological diseases. Remarkably, these therapeutic effects can occur without macroscopic temperature rise, suggesting localized nanoparticle heating, and minimizing side effects on healthy tissues. Nanothermometry has received considerable attention as a means of developing nanothermosensing approaches to monitor the temperature at the core of nanoparticle atoms inside cells. In this study, a label-free, direct, and universal nanoscale thermometry is proposed to monitor the thermal processes of nanoparticles under photoexcitation in the tumor environment. Gold-iron oxide nanohybrids are utilized as multifunctional photothermal agents internalized in a 3D tumor model of glioblastoma that mimics the in vivo scenario. The local temperature under near-infrared photo-excitation is monitored by X-ray absorption spectroscopy (XAS) at the Au L3-edge (11 919 eV) to obtain their temperature in cells, deepening the knowledge of nanothermal tumor treatments. This nanothermometric approach demonstrates its potential in detecting high nanothermal changes in tumor-mimicking tissues. It offers a notable advantage by enabling thermal sensing of any element, effectively transforming any material into a nanothermometer within biological environments., Comunidad de Madrid, Ministerio de Ciencia e Innovación (España), Fondo Europeo de Desarrollo Regional (Unión Europea), Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

2023 Acuerdos transformativos CRUE, Topological superconductors are foreseen as good candidates for the search of Majorana zero modes, where they appear as edge states and can be used for quantum computation. In this context, it becomes necessary to study the robustness and behavior of electron states in topological superconductors when a magnetic or non-magnetic impurity is present. The focus is on scattering resonances in the bands and on spin texture to know what the spin behavior of the electrons in the system will be. It is found that the scattering resonances appear outside the superconducting gap, thus providing evidence of topological robustness. Non-trivial and anisotropic spin textures related to the Dzyaloshinskii–Moriya interaction are also found. The spin textures show a Ruderman–Kittel–Kasuya–Yosida interaction governed by Friedel oscillations. It is believed that the results are useful for further studies which consider many-point-impurity scattering or a more structured impurity potential with a finite range., Ministerio de Ciencia e Innovación (España), Unión Europea-NextGeneration, Fondo Nacional de Desarrollo Científico y Tecnológico (Chile), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Lattice-melting transition; Disorder; Glass; Superconductors; Line; NiBi_(3); Vortex dynamics; Critical current; Pinning force, We investigate the vortex phase diagram of needle shaped high quality NiBi3 single crystals by transport measurements. The current is applied along the crystalline b-axis of this intermetallic quasi-1D BCS superconductor. The single crystals show a Ginzburg-Levanyuk (G (i)) parameter of about 10(-7), larger by two orders of magnitude than G _(i) in elemental low T_(c) BCS superconductors. Vortex phase diagram, critical currents and pinning forces have been extracted from the experimental data. We observe (i) an enhancement of the vortex liquid phase, (ii) a reentrance of the liquid phase at low fields and (iii) an unusual magnetic field dependence of the pinning force. We suggest that these phenomena result from the interplay between pinning due to quenched disorder and the quasi-1D character of the material which could lead, for instance, to more complex pinning mechanisms at play., Unión Europea. H2020, Ministerio de Ciencia e Innovación (MICINN)/ FEDER, Ministerio de Ciencia e Innovación (MICINN)/ FSE, Ministerio de Ciencia e Innovación (MICINN), Ministerio de Educación, Ciencia, Investigación y Deporte de la República Eslovaca / Ministerio de Economía de la República Eslovaca / FEDER, Comunidad de Madrid, Pavol Jozef Šafárik University, Institute of Experimental Physics Slovak Academy of Sciences, Centros de Excelencia Severo Ochoa (MICINN), Unidad de Excelencia María de Maeztu (MICINN), Programa Ramón y Cajal, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

2023 Acuerdos transformativos CRUE, The identification of the active phase of a catalyst under operando conditions is probably the most relevant task in basic catalysis research. In this respect, the Ru(0001) surface during CO oxidation is a traditional studied model, for both its importance in applied catalysis and for its peculiar behavior. In this work, we study the CO catalytic oxidation reaction on flat and defective Ru(0001) surfaces, concluding that the highest activity is achieved in oxidizing conditions when a disordered and thin Ru oxide is formed at the surface. Also, we find that in defective surfaces, with a high density of surface steps, this reaction is enhanced, related to the facile sub-surface incorporation of atomic oxygen and to the easier formation of the oxide. Thus, the CO catalytic oxidation on Ru(0001) is a structure-sensitive reaction, being active on the surface of the oxide formed in reaction conditions., Ministerio de Economía y Competitividad (España), Ministerio de Ciencia e Innovación (España), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2023 American Physical Society This work was supported by the French Agence Nationale de la Recherche (ANR), project SurMott, Ref. No. NT-09-618999. We acknowledge financial support from the Spanish Ministry of Science and Innovation through Projects No. MAT2017-88258-R, No. PID2021-123295NB-I00, No. PID2020-117024GB-C43, No. PID2021-125604NB-I00, and No. CEX2018-000805-M (María de Maeztu Programme for Units of Excellence in R&D). We also acknowledge the technical support provided by the Centro de Computación Científica-UAM (CCC-UAM), Project No. BIOFAST. We thank Professor D. Farías for many helpful discussions., We report an experimental and theoretical study of the electron-phonon coupling for alpha-Sn/Ge(111), a prototypical triangular lattice surface, closely related to Sn/Si(111)-( √3 x √3), where recent experimental evidence has found superconductivity [X. Wu et al., Phys. Rev. Lett. 125, 117001 (2020)]. We concentrate our study on the (3 x 3) phase of alpha-Sn/Ge(111) that appears between 150 and 120 K and has a well-known geometry with a half-filled electronic band around the Fermi energy. We show that this surface presents a giant electron-phonon interaction that can be considered at least partially responsible for the different phases that this system shows at very low temperature. Our theoretical results indicate that indeed the electron-phonon interaction in alpha-Sn/Ge(111)-(3 x 3) is unusually large, since we find that lambda, the electron mass enhancement for the half-filled band, is lambda = 1.3. This result is in good agreement with the experimental value obtained from high-resolution angle-resolved photoemission spectroscopy measurements, which yield lambda = 1.45 +/- 0.1, Ministerio de Ciencia e Innovación (MICINN), Unidades de Excelencia María de Maeztu (MICINN), French Agence Nationale de la Recherche (ANR), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2023 American Physical Society This work was supported by the Universidad Complutense de Madrid through Grant No. FEI-EU-19-12, We study a gas of interacting ultracold bosons held in a parabolic trap in the presence of an optical lattice potential. Treating the system as a discretized Gross-Pitaevskii model, we show how Floquet engineering, by rapidly "shaking" the lattice, allows the ground state of the system to be converted into a train of bright solitons by inverting the sign of the hopping energy. We study how the number of solitons produced depends on the system's nonlinearity and the curvature of the trap, show how the technique can be applied in both the high-and low-driving-frequency regimes, and demonstrate the phenomenon's stability against noise. We conclude that the Floquet approach is a useful and stable method of preparing solitons in cold-atom systems, Universidad Complutense de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2023 by the authors. Licensee MDPI, This work has been funded by the Complutense University—Comunidad de Madrid via project PR65/19-22464., This research has been conducted to characterize and validate resistive heating as a synthesis method for zirconium oxides (ZrO_(2)). A wire of Zr has been oxidized to form a core-shell structure, in which the core is a metal wire, and the shell is an oxide layer that is around 10 mu m thick. The characterization of the samples has been performed by means of several techniques based on Scanning Electron Microscopy (SEM). The topography images show that thermal gradient appears to have little influence on morphology, unlike time, which plays an important role. The chemical composition was analyzed by X-ray spectroscopy (EDX) and X-ray diffraction (XRD), and Raman spectroscopy has been used to assess crystallinity and crystal structure. The oxide layer is mainly formed by monoclinic ZrO_(2), alongside other, less significant, phases. Photoluminescence (PL) and cathodoluminescence (CL) measurements have allowed us to study the distribution of defects along the shell and to confirm the degree of uniformity. The oxygen vacancies, either as isolated defects or forming complexes with impurities, play a determinant role in the luminescent processes. Color centers, mainly electron centers such as F, F-A and F-AA, give rise to several visible emissions extending from blue to green, with main components at around 2 eV, 2.4-2.5 eV and 2.7 eV. The differences between PL and CL in relation to distinct recombination paths are also discussed., Comunidad de Madrid / Universidad Complutense de Madrid (UCM), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Today’s environmental needs require the reduction of the weight of vehicles, thus reducing fuel consumption and associated emissions. For this reason, the use of light alloys is being studied, which, due to their reactivity, must be protected before use. In this work, the effectiveness of a hybrid sol-gel coating doped with various organic environmentally friendly corrosion inhibitors applied to an AA2024 lightweight aluminium alloy is evaluated. Some of the inhibitors tested are pH indicators, acting as both corrosion inhibitors and optical sensors for the surface of the alloy. Samples are subjected to a corrosion test in a simulated saline environment and characterised before and after the test. The experimental results regarding their best inhibitor performance for their potential application in the transport industry are evaluated., Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía, Comercio y Empresa (España), Depto. de Física de Materiales, Fac. de Ciencias Físicas, Instituto de Magnetismo Aplicado (IMA), TRUE, pub

© 2001 The American Physical Society. A. Mu., F. J. G. de A., and J. E. O. are supported by the Universidad del País Vasco (1/UPV/EHU/00057.240-EA-8078/2000) and the Max Planck Research Award Program. V. R. and S. R. are supported by the CNRS-ULTIMATECH program, the CRIF, and the Université de Paris 7. A. Ma. is supported by a Marie Curie Fellowship of the European Union, under Contract No. HPMF-CT-2000-00565. V. P.-D. is supported by the Comunidad Autónoma de Madrid (Project No. 07N/0042/98) and the DEFICIT (Spain) (Grant No. PB-97-1199). The experiments performed at LURE were funded by the Large Scale Facilities program of the European Union. Critical reading of the manuscript by F. J. Himpsel is acknowledged. Technical support from the Spanish-French beam line staff is gratefully acknowledged., STM images show that vicinal Au(788) surfaces are made up or a uniform array of (111)-oriented terraces of similar width (similar to3.8 nm). This uniformity makes it possible to study the electronic Structure of the resulting step superlattice by angle-resolved photoemission. We show that for this terrace array the surface state appears to be broken up into one-dimensional quantum-well levels, indicating total electron confinement within the terraces. The angular resolution allows the probability density of the terrace quantum well state to be mapped in reciprocal space, complementing nicely the wave function measured in real space by STM., Universidad del País Vasco, CNRS-ULTIMATECH, CRIF, Université de Paris 7, Marie Curie Fellowship of the European Union, Comunidad Autónoma de Madrid, DEFICIT (Spain), Max Planck Research Award Program, Large Scale Facilities program of the European Union, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© Institute of Physics This research was supported by the U.S. Department of Energy under contracts No. DEAC04-94AL85000 and DE-AC02-05CH11231 and by the Spanish Ministry of Science and Innovation under Projects No. MAT2009-14578-C03-01 and No. FIS2007-64982., For the non-magnetic system of Ag films on Ru(0001), we have measured the circular dichroism of photoelectrons emitted along the surface normal, the geometry typically used in photoemission electron microscopy. Photoemission spectra were acquired from micrometer-sized regions having uniformly thick Ag films on a single, atomically flat Ru terrace. For a single Ag layer, we find a circular dichroism that exceeds 6% at the d-derived band region around 4.5 eV binding energy. The dichroism decreases as the Ag film thickness increases to three atomic layers. We discuss the origin of the circular dichroism in terms of the symmetry lowering that can occur even in normal emission., US Department of Energy, Spanish Ministry of Science and Innovation, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 1996 - Elsevier Science S.A.. International Workshop on Beam Injection Assessment of Defects in Semiconductors (BIADS 96) (4. 1996. El Escorial, España). A. Cremades thanks the Universidad Complutense for a predoctoral grant. This work has been partially supported by DGICYT Projects No. HP95-98B and PB93- 1256., GaN epitaxial layers have been investigated by cathodoluminescence (CL) in the scanning electron microscope (SEM). The most prominent feature of the spectra is a complex band at 2.2 eV, whose evolution with temperature and excitation density suggests emission mechanisms involving a deep center and donor-donor or donor-acceptor pairs. Time resolved photoluminescence (TRPL) measurements confirm the involvement of a deep center in the emission. CL images reveal that the centers responsible for this emission decorate grain boundaries. Emission bands al 2.87 eV and 1.31 eV have been also detected in the films., DGICYT (Spain), Universidad Complutense, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© EDP Sciences. International Conference on Defects - Recognition, Imaging and Physics in Semiconductors (DRIP 10). (10.2003.Batz sur Mer, FRANCE ). This work has been supported by MCYT (Project MAT 2000- 2119). R. Plugaru acknowledges MECD for the research grant SB2000-0164., The luminescence of amorphous silicon layers either implanted with Er or co-implanted with Er and O has been studied by photoluminescence (PL) and cathodoluminescence (CL) in the scanning electron microscope. Annealing in nitrogen causes the formation of oxide species and Er-Si complexes or precipitates as well a spectral changes in the visible and infrared ranges. The main CL emission takes place in the visible range while PL spectra reveal intense visible and infrared emission. CL spectra show blue-violet, or green, emission bands whose relative intensities depend on the post-implantation annealing temperature. The PL spectra show a blue-violet band with a series of lines in the violet region related to phonon assisted transitions as well as different emission bands in the range 1200-1500 nm. The influence of the annealing-induced structural changes on the observed spectra is discussed., MCYT, MECD, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2002 American Institute of Physics. This work was supported by MCYT /Project MAT2000-2119)., Near-field cathodoluminescence (NFCL) has been used to characterize hydride vapor phase epitaxy grown n-GaN films. This technique can obtain high resolution luminescence images and perform local measurements of the diffusion length for minority carriers in different parts of the sample. NFCL contrast observed in round growth hillocks at the sample surface, with a diameter of less than 10 mum, is compared with that observed by conventional cathodoluminescence in scanning electron microscope (CLSEM) techniques. In particular NFCL images reveal features not detected by CLSEM which is explained by the fact that under near field conditions the signal arises from a depth of only several tens of nanometers and is then directly related to the surface hillocks. Diffusion lengths of about 0.4 and 4 mum have been found for the holes in different regions of the samples at room temperature. The order of magnitude of these minority carriers diffusion lengths is in good agreement with previous measurements performed at different GaN samples with other techniques. The NFCL contrast and the differences in the measured diffusion lengths are discussed and explained by variations in local trap concentrations., MCYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2003 Elsevier Science B.V. All rights reserved. The authors want to thank V. A. Malyshev for the critical reading of the manuscript. Work in Madrid was supported by DGI-MCyT (Project MAT2000-0734) and CAM (Project 07N/0075/2001). P. Orellana would like to thank Milenio ICM P99-135-F and Cátedra Presidencial de Ciencias for financial support., We present a novel model to calculate vertical transport properties such as conductance and current in unintentionally disordered double-barrier GaAs-AlxGa1-xAs heterostructures. The source of disorder comes from interface roughness at the heterojunctions (lateral disorder) as well as spatial inhomogeneities of the Al mole fraction in the barriers (compositional disorder). Both lateral and compositional disorder break translational symmetry along the lateral direction and therefore electrons can be scattered off the growth direction. The model correctly describes channel mixing due to these elastic scattering events. In particular, for realistic degree of disorder, we have found that the effects of compositional disorder on transport properties are negligible as compared to the effects due to lateral disorder., DGI-MCyT, CAM, Milenio ICM, Cátedra Presidencial de Ciencias, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2010 The American Physical Society. Travel between Bayreuth and Madrid was supported by the joint program Acciones Integradas of Deutscher Akademscher Auslandsdienst (DAAD) and Ministerio de Educación y Ciencia (MEC). C.G. and C.A.M acknowledge financial support from Deutsche Forschungsgemeinschaft (DFG), and thank H.-C. Nägerl and his group for hospitality and helpful discussions. Work at Madrid was supported by MEC (Project MOSAICO). Work at Maceio was partially supported by the Brazilian research agencies Conselho Nacional de Desenvolvimento Científico e Tecnologico (CNPq) and Coordenac ión de Aperfecionamiento de Pessoal de Nível Superior (CAPES)., Bloch oscillations of Bose-Einstein condensates realize sensitive matter-wave interferometers. We investigate the dynamics and stability of bright-soliton wave packets in one-dimensional tilted optical lattices with a modulated mean-field interaction g(t). By means of a time-reversal argument, we prove the stability of Bloch oscillations of breathing solitons that would be quasistatically unstable. Floquet theory shows that these breathing solitons can be more stable against certain experimental perturbations than rigid solitons or even noninteracting wave packets., Deutscher Akademischer Auslandsdienst (DAAD), Ministerio de Educacion y Ciencia (MEC), Deutsche Forschungsgemeinschaft (DFG), MEC, Brazilian research agencies Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Institute of Physics. The authors wish to thank D. C. Look, H. Morkoc¸ and J. van Nostrand for providing the investigated material. C. D.-G. acknowledges M. E. C. D. for a postdoctoral research grant. This work has been partially supported by MCYT through Project No. MAT2000-2119., Time-resolved cathodoluminescence (TRCL) and photocurrent (PC) spectroscopies have been applied to the study of the yellow band of Si-doped GaN. Measurements carried out combining both techniques unambiguously reveal the complex nature of this broad emission and confirm that different deep defect levels are involved in the observed luminescence. Five emission bands centered at 1.89, 2.03, 2.16, 2.29, and 2.38 eV were found by steady state and time-resolved CL investigations, while PC spectra showed four transitions at about 2.01, 2.14, 2.28, and 2.43 eV. The behavior of the deep-level emissions intensity as a function of the excitation pulse width as well as their decay times were investigated by TRCL. A decay time of 245 mus was measured for the 2.29 eV emission band, while longer decay times of 315 and 340 mus were found, respectively, for the 2.16 and 2.38 eV bands, in agreement with TRCL spectra. The appearance of the 2.03, 2.16, 2.29 eV and 2.38-2.43 eV peaks both in PC and CL spectra suggests that these bands are related to deep acceptor to band transitions, as supported by the single exponential character of the corresponding decay transients., MCYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub