48 results on '"Muñoz-Noval, A."'
Search Results
2. Influence of the sputtering flow regime on the structural properties and magnetic behavior of Fe-Ga thin films (Ga ∼ 30 at.%)
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Muñoz Noval, Álvaro, Ordóñez Fontes, A., Ranchal Sánchez, Rocío, Muñoz Noval, Álvaro, Ordóñez Fontes, A., and Ranchal Sánchez, Rocío
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©2016 American Physical Society. This paper has been financially supported through of the Spanish Ministry of Economy and Competitiveness (MINECO), MAT2015-66888-C3-3-R. We thank “CAI Difracción de rayos-X” of Universidad Complutense de Madrid for the x-ray diffractometry measurements and Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM) for the use of some of its facilities. We also thank BM25-SpLine, the Spanish CRG at ESRF for providing beam time., In this paper we analyze the structure of Fe-Ga layers with a Ga content of ∼30 at.% deposited by the sputtering technique under two different regimes. We also studied the correlation between the structure and magnetic behavior of the samples. Keeping the Ar pressure fixed, we modified the flow regime from ballistic to diffusive by increasing the distance between the target and the substrate. X-ray diffraction measurements have shown a lower structural quality when growing in the diffusive flow. We investigated the impact of the growth regime by means of x-ray absorption fine structure (XAFS) measurements and obtained signs of its influence on the local atomic order. Full multiple scattering and finite difference calculations based on XAFS measurements point to a more relevant presence of a disordered A2 phase and of orthorhombic Ga clusters on the Fe-Ga alloy deposited under a diffusive regime; however, in the ballistic sample, a higher presence of D0_3/B2 phases is evidenced. Structural characteristics, from local to long range, seem to determine the magnetic behavior of the layers. Whereas a clear in-plane magnetic anisotropy is observed in the film deposited under ballistic flow, the diffusive sample is magnetically isotropic. Therefore, our experimental results provide evidence of a correlation between flow regime and structural properties and its impact on the magnetic behavior of a rather unexplored compositional region of Fe-Ga compounds., Ministerio de Economía y Competitividad (MINECO), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub
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- 2023
3. X-Ray Nanothermometry of Nanoparticles in Tumor-Mimicking Tissues under Photothermia
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Comunidad de Madrid, Ministerio de Ciencia e Innovación (España), Consejo Superior de Investigaciones Científicas (España), López-Méndez, Rosalía, Reguera, Javier, Fromain, Alexandre, Serea, Esraa Samy Abu, Céspedes, Eva, Teran, Francisco José, Zheng, Fangyuan, Parente, Ana, García García-Tuñón, Miguel Ángel, Fonda, Emiliano, Camarero, Julio, Wilhelm, Claire, Muñoz-Noval, Álvaro, Espinosa, Ana, Comunidad de Madrid, Ministerio de Ciencia e Innovación (España), Consejo Superior de Investigaciones Científicas (España), López-Méndez, Rosalía, Reguera, Javier, Fromain, Alexandre, Serea, Esraa Samy Abu, Céspedes, Eva, Teran, Francisco José, Zheng, Fangyuan, Parente, Ana, García García-Tuñón, Miguel Ángel, Fonda, Emiliano, Camarero, Julio, Wilhelm, Claire, Muñoz-Noval, Álvaro, and Espinosa, Ana
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[EN] 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 L-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.
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- 2023
4. Realization of macroscopic ratchet effect based on nonperiodic and uneven potentials
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Rollano V., Gomez A., Muñoz-Noval A., Velez M., de Ory M.C., Menghini, Mariela, Gonzalez E.M., Vicent, José Luis, Rollano V., Gomez A., Muñoz-Noval A., Velez M., de Ory M.C., Menghini, Mariela, Gonzalez E.M., and Vicent, José Luis
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- 2021
5. Photoactivated Nanoscale Temperature Gradient Detection Using X-ray Absorption Spectroscopy as a Direct Nanothermometry Method
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Espinosa, Ana, Castro G.R., Reguera J., Castellano C., Castillo J., Camarero, Julio, Wilhelm C., García M.A., Muñoz-Noval A., Espinosa, Ana, Castro G.R., Reguera J., Castellano C., Castillo J., Camarero, Julio, Wilhelm C., García M.A., and Muñoz-Noval A.
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- 2021
6. Realization of macroscopic ratchet effect based on nonperiodic and uneven potentials
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Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), European Commission, Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Rollano, Víctor, Gómez, Alicia, Muñoz-Noval, Alvaro, Vélez, María, Calero de Ory, Marina, Menghini, M., González, Elvira M., Vicent, J. L., Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), European Commission, Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Rollano, Víctor, Gómez, Alicia, Muñoz-Noval, Alvaro, Vélez, María, Calero de Ory, Marina, Menghini, M., González, Elvira M., and Vicent, J. L.
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Ratchet devices allow turning an ac input signal into a dc output signal. A ratchet device is set by moving particles driven by zero averages forces on asymmetric potentials. Hybrid nanostructures combining artificially fabricated spin ice nanomagnet arrays with superconducting films have been identified as a good choice to develop ratchet nanodevices. In the current device, the asymmetric potentials are provided by charged Néel walls located in the vertices of spin ice magnetic honeycomb array, whereas the role of moving particles is played by superconducting vortices. We have experimentally obtained ratchet effect for different spin ice I configurations and for vortex lattice moving parallel or perpendicular to magnetic easy axes. Remarkably, the ratchet magnitudes are similar in all the experimental runs; i. e. different spin ice I configurations and in both relevant directions of the vortex lattice motion. We have simulated the interplay between vortex motion directions and a single asymmetric potential. It turns out vortices interact with uneven asymmetric potentials, since they move with trajectories crossing charged Néel walls with different orientations. Moreover, we have found out the asymmetric pair potentials which generate the local ratchet effect. In this rocking ratchet the particles (vortices) on the move are interacting each other (vortex lattice); therefore, the ratchet local effect turns into a global macroscopic effect. In summary, this ratchet device benefits from interacting particles moving in robust and topological protected type I spin ice landscapes.
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- 2021
7. Little–Parks effect governed by magnetic nanostructures with out-of-plane magnetization
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de Ory M.C., Rollano V., Gomez A., Menghini, Mariela, Muñoz-Noval A., Gonzalez E.M., Vicent, José Luis, de Ory M.C., Rollano V., Gomez A., Menghini, Mariela, Muñoz-Noval A., Gonzalez E.M., and Vicent, José Luis
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- 2020
8. Janus Magnetic-Plasmonic Nanoparticles for Magnetically Guided and Thermally Activated Cancer Therapy
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Espinosa, Ana, Reguera J., Curcio A., Muñoz-Noval Á., Kuttner C., Van de Walle A., Liz-Marzán L.M., Wilhelm C., Espinosa, Ana, Reguera J., Curcio A., Muñoz-Noval Á., Kuttner C., Van de Walle A., Liz-Marzán L.M., and Wilhelm C.
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- 2020
9. Little–Parks effect governed by magnetic nanostructures with out-of-plane magnetization
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Calero de Ory, Marina, Rollano, V., Gómez, Alicia, Menghini, M., Muñoz-Noval, Alvaro, González, Elvira M., Vicent, J.L., Calero de Ory, Marina, Rollano, V., Gómez, Alicia, Menghini, M., Muñoz-Noval, Alvaro, González, Elvira M., and Vicent, J.L.
- Abstract
Little–Parks effect names the oscillations in the superconducting critical temperature as a function of the magnetic field. This effect is related to the geometry of the sample. In this work, we show that this effect can be enhanced and manipulated by the inclusion of magnetic nanostructures with perpendicular magnetization. These magnetic nanodots generate stray fields with enough strength to produce superconducting vortex–antivortex pairs. So that, the L–P effect deviation from the usual geometrical constrictions is due to the interplay between local magnetic stray fields and superconducting vortices. Moreover, we compare our results with a low-stray field sample (i.e. with the dots in magnetic vortex state) showing how the enhancement of the L–P effect can be explained by an increment of the effective size of the nanodots.
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- 2020
10. Crystal defects and optical emissions of pulse electrodeposited ZnO
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Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Comunidad de Madrid, European Commission, Consejo Superior de Investigaciones Científicas (España), Manzano, Cristina V., Serrano Rubio, Aída, Muñoz-Noval, Alvaro, Fernández Lozano, José Francisco, Martín-González, Marisol, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Comunidad de Madrid, European Commission, Consejo Superior de Investigaciones Científicas (España), Manzano, Cristina V., Serrano Rubio, Aída, Muñoz-Noval, Alvaro, Fernández Lozano, José Francisco, and Martín-González, Marisol
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ZnO has been widely studied in the last decades as an n-type semiconductor due to its wide application range, for example, in optoelectronics, solar cells, light-emitting diodes, thermoelectrics, amongst others. The material efficiency for certain applications is highly dependent on the presenting film morphology. Electrodeposition is well-known as a technique with precise control over the structural and morphological properties of the obtained materials. When the structural and morphological properties are tuned, it is possible to find a wide variety of defects in the ZnO structure. In this study, ZnO films were grown using pulsed electrodeposition with variation of the reduction potential. The crystal order, structural defects and optical emissions of the films have been analyzed by X-Ray Diffraction (XRD), X-ray Absorption Near-Edge Structure (XANES), Extended X-ray Absorption Fine Structure (EXAFS) and Photoluminescence (PL). ZnO film grown at less negative reduction potential presents a stronger texture along [0001] by XRD, higher crystalline order, and more zinc vacancies by XANES and EXAFS. The films obtained at less negative potential present less OH trapped in the ZnO structure and a relatively higher level of defects O, O, O and O than those grown at higher reduction potentials by PL. This will be related to the fact that at less negative potentials there is less concentration of OH at the film surface than at more negative potentials. The combination of X-ray absorption spectroscopy and photoluminescence reveals the complicated nature of the atomic defect in electrodeposited ZnO films. Allowing to evidence the preferential presence of atomic defect as a function of the reduction potential. In this work, we have also compared those defects with reference compounds such as a Zn foil and ZnO polycrystalline powder.
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- 2020
11. Unveiling the different physical origins of magnetic anisotropy and magnetoelasticity in Ga-Rich FeGa thin films
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Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Gobierno de Aragón, Comunidad de Madrid, European Commission, Universidad Complutense de Madrid, Bartolomé, P., Begué Gracia, Adrián, Muñoz-Noval, Alvaro, Ciria, Miguel, Ranchal, R., Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Gobierno de Aragón, Comunidad de Madrid, European Commission, Universidad Complutense de Madrid, Bartolomé, P., Begué Gracia, Adrián, Muñoz-Noval, Alvaro, Ciria, Miguel, and Ranchal, R.
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The aim of this work is to clarify how in-plane magnetic anisotropy and magnetoelasticity depend on the thickness of Ga-rich FeGa layers. Samples with an Fe72Ga28 composition were grown by sputtering in the ballistic regime in oblique incidence. Although for these growth conditions uniaxial magnetic anisotropy could be expected, in-plane anisotropy is only present when the sample thickness is above 100 nm. By means of differential X-ray absorption spectroscopy, we have determined the influence of both Ga pairs and tetragonal cell distortion on the evolution of the magnetic anisotropy with the increase of FeGa thickness. On the other hand, we have used the cantilever beam technique with capacitive detection to also determine the evolution of the magnetoelastic parameters with the thickness increase. In this case, experimental results can be understood considering the grain distribution. Therefore, the different physical origins for anisotropy and magnetoelasticity open up the possibility to independently tune these two characteristics in Ga-rich FeGa films.
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- 2020
12. Vortex dynamics controlled by local superconducting enhancement
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Rollano V., Gomez A., Muñoz-Noval A., Del Valle J., Menghini, Mariela, De Ory M.C., Prieto J.L., Navarro E., Gonzalez E.M., Vicent, José Luis, Rollano V., Gomez A., Muñoz-Noval A., Del Valle J., Menghini, Mariela, De Ory M.C., Prieto J.L., Navarro E., Gonzalez E.M., and Vicent, José Luis
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- 2019
13. Topologically protected superconducting ratchet effect generated by spin-ice nanomagnets
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Rollano V., Muñoz-Noval A., Gomez A., Valdes-Bango F., Martin J.I., Velez M., Osorio M.R., Granados, Daniel, Gonzalez E.M., Vicent, José Luis, Rollano V., Muñoz-Noval A., Gomez A., Valdes-Bango F., Martin J.I., Velez M., Osorio M.R., Granados, Daniel, Gonzalez E.M., and Vicent, José Luis
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- 2019
14. Frustrated spin ice nanomagnets probed by superconducting vortex dynamics
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Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Commission, Vicent, J. L., Rollano, Víctor, Muñoz-Noval, Alvaro, Gómez, Alicia, Martín, José Ignacio, Valdés-Bango, F., Vélez, María, Osorio, M. R., Granados, D., González, Elvira M., Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Commission, Vicent, J. L., Rollano, Víctor, Muñoz-Noval, Alvaro, Gómez, Alicia, Martín, José Ignacio, Valdés-Bango, F., Vélez, María, Osorio, M. R., Granados, D., and González, Elvira M.
- Abstract
Resumen del trabajo presentado al American Physical Society (APS) March Meeting, celebrado del 4 al 8 de 2019 en Boston, Massachusetts (USA).
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- 2019
15. Self-assembly of iron oxide precursor micelles driven by magnetic stirring time in sol-gel coatings
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López-Sánchez, Jesús, Serrano Rubio, Aída, del Campo, A., de la Figuera, Juan, Marco, J.F., Abuín, M., Muñoz-Noval, A., Carmona, N., Rodríguez de la Fuente, Óscar, Martín, Pilar, López-Sánchez, Jesús, Serrano Rubio, Aída, del Campo, A., de la Figuera, Juan, Marco, J.F., Abuín, M., Muñoz-Noval, A., Carmona, N., Rodríguez de la Fuente, Óscar, and Martín, Pilar
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- 2019
16. Magnetic multilayers with competing in plane and out of plane anisotropies
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Muñoz-Noval, Alvaro, Rollano, Víctor, Gómez, Alicia, García García-Tuñón, Miguel Ángel, Calero de Ory, Marina, Vélez, María, González, Elvira M., Vicent, J. L., Muñoz-Noval, Alvaro, Rollano, Víctor, Gómez, Alicia, García García-Tuñón, Miguel Ángel, Calero de Ory, Marina, Vélez, María, González, Elvira M., and Vicent, J. L.
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Multilayers formed by layers with different anisotropy conform one of the most interesting kinds of magnetic multi-layered systems. In particular, multilayers combining films with in plane and out of plane anisotropy provide a wide range of magnetic properties depending on the dominant anisotropy and the degree of coupling between the layers. When employed as spacers, some metals can induce a strong modulation in the coupling, which can be controlled using different spacer thicknesses. Here, we report on a particular system consisting of a perpendicular magnetic anisotropy (PMA) [Co/Pd]n multilayer with an in-plane shape anisotropy Permalloy (Py) layer. Our multi-layered system is grown by sputtering and its magnetic properties studied by Magneto-optical Kerr effect (MOKE) and magnetic force microscopy (MFM). To achieve tuneable magnetization angles and tailor the degree of coupling, we employ a non- magnetic spacer of variable thickness (ruthenium). The PMA of the multilayers can be enhanced by increasing the number of units, adding an additional degree of freedom. In this study, we vary systematically the [Co/Pd]n multilayer structure and spacer thickness. The magnetic coupling is investigated combining magnetization measurements by MOKE at room temperature in longitudinal and polar configuration, thus measuring in plane and out of plane magnetization, with MFM to get the domain structure.
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- 2019
17. Defects in ZnO obtained by electrochemical reactions
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Manzano, Cristina V., Serrano Rubio, Aída, Muñoz-Noval, A., Fernández Lozano, José Francisco, Martín-González, Marisol, Manzano, Cristina V., Serrano Rubio, Aída, Muñoz-Noval, A., Fernández Lozano, José Francisco, and Martín-González, Marisol
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- 2019
18. AMPHIBIAN UCM experimental data Epsilon solgel RSCAdv2019
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European Commission, López-Sánchez, Jesús, Serrano Rubio, Aída, Campo, Ángel Adolfo del, Abuín, M., Salas, Eduardo, Muñoz-Noval, A., Castro, Germán R., de la Figuera, Juan, Marco, J.F., Marín, Pilar, Carmona, N., Rodríguez de la Fuente, Óscar, AMPHIBIAN Project ID:720853, European Commission, López-Sánchez, Jesús, Serrano Rubio, Aída, Campo, Ángel Adolfo del, Abuín, M., Salas, Eduardo, Muñoz-Noval, A., Castro, Germán R., de la Figuera, Juan, Marco, J.F., Marín, Pilar, Carmona, N., Rodríguez de la Fuente, Óscar, and AMPHIBIAN Project ID:720853
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- 2019
19. Topologically protected superconducting ratchet effect generated by spin-ice nanomagnets
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Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Vicent, J. L. [0000-0001-9343-7671], Rollano, Víctor, Muñoz-Noval, Alvaro, Gómez, Alicia, Valdés-Bango, F., Martín, José Ignacio, Vélez, María, Osorio, M. R., Granados, D., González, Elvira M., Vicent, J. L., Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Vicent, J. L. [0000-0001-9343-7671], Rollano, Víctor, Muñoz-Noval, Alvaro, Gómez, Alicia, Valdés-Bango, F., Martín, José Ignacio, Vélez, María, Osorio, M. R., Granados, D., González, Elvira M., and Vicent, J. L.
- Abstract
We have designed, fabricated and tested a robust superconducting ratchet device based on topologically frustrated spin ice nanomagnets. The device is made of a magnetic Co honeycomb array embedded in a superconducting Nb film. This device is based on three simple mechanisms: (i) the topology of the Co honeycomb array frustrates in-plane magnetic configurations in the array yielding a distribution of magnetic charges which can be ordered or disordered with in-plane magnetic fields, following spin ice rules; (ii) the local vertex magnetization, which consists of a magnetic half vortex with two charged magnetic Néel walls; (iii) the interaction between superconducting vortices and the asymmetric potentials provided by the Néel walls. The combination of these elements leads to a superconducting ratchet effect. Thus, superconducting vortices driven by alternating forces and moving on magnetic half vortices generate a unidirectional net vortex flow. This ratchet effect is independent of the distribution of magnetic charges in the array.
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- 2019
20. Self-assembly of iron oxide precursor micelles driven by magnetic stirring time in sol–gel coatings
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European Commission, Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Consejo Superior de Investigaciones Científicas (España), López-Sánchez, Jesús [0000-0002-2670-9347], Serrano, Aida [0000-0002-6162-0014], Salas- Colera, Eduardo [0000-0001-7812-268X], Rodríguez-de- la-Fuente, Oscar [0000-0002-6888-459X], López-Sánchez, Jesús, Serrano Rubio, Aída, Campo, Ángel Adolfo del, Abuín, M., Salas, Eduardo, Muñoz-Noval, A., Castro, Germán R., de la Figuera, Juan, Marco, J.F., Marín, Pilar, Carmona, N., Rodríguez de la Fuente, Óscar, AMPHIBIAN Project ID:720853, European Commission, Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Consejo Superior de Investigaciones Científicas (España), López-Sánchez, Jesús [0000-0002-2670-9347], Serrano, Aida [0000-0002-6162-0014], Salas- Colera, Eduardo [0000-0001-7812-268X], Rodríguez-de- la-Fuente, Oscar [0000-0002-6888-459X], López-Sánchez, Jesús, Serrano Rubio, Aída, Campo, Ángel Adolfo del, Abuín, M., Salas, Eduardo, Muñoz-Noval, A., Castro, Germán R., de la Figuera, Juan, Marco, J.F., Marín, Pilar, Carmona, N., Rodríguez de la Fuente, Óscar, and AMPHIBIAN Project ID:720853
- Abstract
[EN] The purpose of this work is to fabricate self-assembled microstructures by the sol–gel method and study the morphological, structural and compositional dependence of 3-Fe2O3 nanoparticles embedded in silica when glycerol (GLY) and cetyl-trimethylammonium bromide (CTAB) are added as steric agents simultaneously. The combined action of a polyalcohol and a surfactant significantly modifies the morphology of the sample giving rise to a different microstructure in each of the studied cases (1, 3 and 7 days of magnetic stirring time). This is due to the fact that the addition of these two compounds leads to a considerable increase in gelation time as GLY can interact with the alkoxide group on the surface of the iron oxide precursor micelle and/or be incorporated into the hydrophilic chains of CTAB. This last effect causes the iron oxide precursor micelles to be interconnected forming aggregates whose size and structure depend on the magnetic stirring time of the sol–gel synthetic route. In this paper, crystalline structure, composition, purity and morphology of the sol–gel coatings densified at 960 ºC are examined. Emphasis is placed on the nominal percentage of the different iron oxides found in the samples and on the morphological and structural differences. This work implies the possibility of patterning 3-Fe2O3 nanoparticles in coatings and controlling their purity by an easy one-pot sol–gel method.
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- 2019
21. Thermal Route for the Synthesis of Maghemite/Hematite Core/Shell Nanowires
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Cortés-Llanos B., Serrano A., Muñoz-Noval A., Urones-Garrote E., Del Campo A., Marco J.F., Ayuso-Sacido A., Pérez, Lucas, Cortés-Llanos B., Serrano A., Muñoz-Noval A., Urones-Garrote E., Del Campo A., Marco J.F., Ayuso-Sacido A., and Pérez, Lucas
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- 2017
22. Correlation between local structure and magnetic behavior in co-sputtered TbxFe73Ga27−x (7 ≤ x ≤ 11) thin films
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Universidad Complutense de Madrid, Ministerio de Economía y Competitividad (España), Muñoz-Noval, A., Salas, Eduardo, Bartolomé, P., Serrano Rubio, Aída, Castro, Germán R., Ranchal, R., Universidad Complutense de Madrid, Ministerio de Economía y Competitividad (España), Muñoz-Noval, A., Salas, Eduardo, Bartolomé, P., Serrano Rubio, Aída, Castro, Germán R., and Ranchal, R.
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We report on the evolution of the microstructure of Tb-Fe-Ga films deposited by co-sputtering from TbFe and FeGa targets. The sputtering power was fixed (90 W) in the FeGa whereas it was increased from 50 to 90 W in the TbFe target resulting on TbFeGa layers with 7 ≤ x ≤ 11. The local structure was determined by means of x-ray absorption fine structure spectroscopy at Fe-K, Ga-K and Tb-L edges. The increase of Tb in the alloy promotes the phase segregation that produces a larger amount of the TbFe structural phase. The structural results have been correlated with the magnetic characterization that shows the enhancement of the out-of-plane component of the magnetization.
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- 2017
23. Morphological, structural and magnetic evolution of sputtered Fe70Ga30 thin films upon annealing in oxygen atmosphere
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Ministerio de Economía y Competitividad (España), Universidad Complutense de Madrid, Álvarez-Álvarez, P., Prados, A., Muñoz-Noval, A., Ranchal, R., Ministerio de Economía y Competitividad (España), Universidad Complutense de Madrid, Álvarez-Álvarez, P., Prados, A., Muñoz-Noval, A., and Ranchal, R.
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We report on the evolution of uncapped FeGa layers deposited by sputtering and post-growth annealed in oxygen atmosphere in a temperature range from 500 °C to 800 °C. We have investigated the morphology, structure and magnetic properties of films with a thickness of 200 nm deposited on Mo buffer layers on glass substrates. X-ray diffractometry shows a decrease of the lattice parameter up to 600 °C whereas a further increase of the temperature up to 800 °C promotes the transformation to FeO. We have observed by x-ray absorption fine structure the partial oxidation of Ga and the formation of Ga aggregates at 600 °C. These aggregates form Ga-rich bubbles that can be observed on the sample surface from which Ga evaporates leaving a Ga-poor layer that is later oxidized into FeO. The thermal treatment on oxygen atmosphere has also a clear impact on the magnetic properties of the layers. The uniaxial in-plane magnetic anisotropy of the as-grown film evolves to magnetic isotropy when annealed at 600 °C probably due to the segregation and formation of Ga-rich areas. After Ga evaporates from the sample, Fe is fully oxidized and only a weak ferromagnetism related to FeO is detected.
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- 2017
24. Anomalous local lattice disorder and distortion in A2Mo2O7 pyrochlores
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Ministerio de Economía y Competitividad (España), European Commission, Castellano, C., Berti, Giulia, Rubio Marcos, Fernando, Lamura, G., Sanna, S., Salas, Eduardo, Brambilla, A., Muñoz-Noval, A., Duò, L., Demartin, F., Ministerio de Economía y Competitividad (España), European Commission, Castellano, C., Berti, Giulia, Rubio Marcos, Fernando, Lamura, G., Sanna, S., Salas, Eduardo, Brambilla, A., Muñoz-Noval, A., Duò, L., and Demartin, F.
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We present an extended X-ray absorption fine structure study of the pyrochlores AMoO (A = Gd, Dy, Ho, Er), as a function of temperature. While in the three spin-glass compositions DyMoO, HoMoO and ErMoO the Debye temperatures are in accordance with other pyrochlores and the static disorder contributions are compatible with a lattice frustration, in the low-temperature-ferromagnetic GdMoO system we point out an anomalous enhancement of the local structure disorder below about 225 K down to low temperatures. Moreover, considering the general pyrochlore predisposition towards structural disorder, we prove the presence on a local scale of at least a bimodal distribution of the Mo-O(1) octahedral interatomic distances for all the studied compounds, consisting of two shorter and four longer bond lengths. Our results suggest that the local structure order parameter plays an important role in the ferromagnetic or spin-glass phase stabilization.
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- 2017
25. Thermal Route for the Synthesis of Maghemite/Hematite Core/Shell Nanowires
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Cortés-Llanos, B., Serrano Rubio, Aída, Muñoz-Noval, A., Urones-Garrote, E., Campo, Ángel Adolfo del, Marco, J.F., Ayuso-Sacido, A., Pérez, Lucas, Cortés-Llanos, B., Serrano Rubio, Aída, Muñoz-Noval, A., Urones-Garrote, E., Campo, Ángel Adolfo del, Marco, J.F., Ayuso-Sacido, A., and Pérez, Lucas
- Abstract
Nowadays, iron oxide-based nanostructures are key materials in many technological areas. Their physical and chemical properties can be tailored by tuning the morphology. In particular, the possibility of increasing the specific surface area has turned iron oxide nanowires (NWs) into promising functional materials in many applications. Among the different possible iron oxide NWs that can be fabricated, maghemite/hematite iron oxide core/shell structures have particular importance since they combine the magnetism of the inner maghemite core with the interesting properties of hematite in different technological fields ranging from green energy to biomedical applications. However, the study of these iron oxide structures is normally difficult due to the structural and chemical similarities between both iron oxide polymorphs. In this work, we propose a route for the synthesis of maghemite/hematite NWs based on the thermal oxidation of previously electrodeposited iron NWs. A detailed spectroscopic analysis based on Raman, Mössbauer, and X-ray absorption shows that the ratio of both oxides can be controlled during fabrication. Transmission electron microscopy has been used to check the core/shell structure of the NWs. The biocompatibility and capability of internalization of these NWs have also been proven to show the potential of these NWs in biomedical applications.
- Published
- 2017
26. Effect of X-ray irradiation on co-phthalocyanine thin films studied by surface plasmon resonance
- Author
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Serrano Rubio, Aída, Rodríguez de la Fuente, O., Monton, C., Muñoz-Noval, A., Valmianski, I., Fernández Lozano, José Francisco, Shuller, Ivan K., Castro, Germán R., García García-Tuñón, Miguel Ángel, Serrano Rubio, Aída, Rodríguez de la Fuente, O., Monton, C., Muñoz-Noval, A., Valmianski, I., Fernández Lozano, José Francisco, Shuller, Ivan K., Castro, Germán R., and García García-Tuñón, Miguel Ángel
- Published
- 2016
27. Temperature dependence on the magnetic, morphological and structural properties of Fe3O4(111)/SrTiO3(111) thin films grown by PLD
- Author
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López-Sánchez, Jesús, Rubio-Zuazo, J., Arnay, I., Muñoz-Noval, A., Serrano Rubio, Aída, Carmona, N., Rodríguez de la Fuente, O., Castro, Germán R., López-Sánchez, Jesús, Rubio-Zuazo, J., Arnay, I., Muñoz-Noval, A., Serrano Rubio, Aída, Carmona, N., Rodríguez de la Fuente, O., and Castro, Germán R.
- Published
- 2016
28. Effect of x-ray irradiation on Co-phthalocyanine thin films studied by surface plasmon resonance
- Author
-
Ministerio de Ciencia e Innovación (España), Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), Department of Energy (US), Serrano Rubio, Aída, Rodríguez de la Fuente, O., Monton, C., Muñoz-Noval, A., Valmianski, I., Fernández Lozano, José Francisco, Castro, Germán R., Schuller, I. K., García García-Tuñón, Miguel Ángel, Ministerio de Ciencia e Innovación (España), Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), Department of Energy (US), Serrano Rubio, Aída, Rodríguez de la Fuente, O., Monton, C., Muñoz-Noval, A., Valmianski, I., Fernández Lozano, José Francisco, Castro, Germán R., Schuller, I. K., and García García-Tuñón, Miguel Ángel
- Abstract
We explore here the effect of x-ray irradiation (7.7 keV) on Co-phthalocyanine (CoPc) thin films using surface plasmon resonance (SPR). We have found a small and partially reversible modification of the SPR spectra of CoPc in CoPc/Au bilayers upon irradiation. For a beam intensity of ∼10 photons • s • mm and an irradiation time of the order of 1 h, we estimate small variations of the order of ∼1-5% in the refractive index associated with the scattering of the x-rays with the soft matter. A Raman study of the irradiated regions did not show structural modifications, suggesting that the observed variations in the optical properties of the CoPc films are related to modifications of their electronic configuration.
- Published
- 2016
29. A-site order in rhombohedral perovskite-like oxides La2-xSrxCoTiO6 (0.6 <= x <= 1.0)
- Author
-
Comunidad de Madrid, Ministerio de Ciencia e Innovación (España), Consejo Superior de Investigaciones Científicas (España), Ministerio de Economía y Competitividad (España), Universidad de San Pablo-CEU, Gómez-Pérez, A., Ritter, C., Boulahya, K., Muñoz-Noval, A., García-Alvarado, F., Amador, U., Comunidad de Madrid, Ministerio de Ciencia e Innovación (España), Consejo Superior de Investigaciones Científicas (España), Ministerio de Economía y Competitividad (España), Universidad de San Pablo-CEU, Gómez-Pérez, A., Ritter, C., Boulahya, K., Muñoz-Noval, A., García-Alvarado, F., and Amador, U.
- Abstract
The evolution of the room-temperature structure of the oxide series LaSrCoTiO (0.6 ≤ x ≤ 1.0) was studied as a function of the Sr content using different diffraction techniques and applying the symmetry-adapted modes formalism (AMPLIMODES). The title compounds adopt perovskite-like structures of rhombohedral symmetry with an octahedral tilting scheme (aaa) with either space group R3¯c or R32. The latter symmetry is observed in those cases (for x ≃ 0.6) where additional rock-salt-like ordering of La and Sr is produced in the perovskite A sites. Two composition-driven phase transitions are observed in the whole series LaSrCoTiO (0.0 ≤ x ≤ 1.0). Using the concept of internal pressure, the effect of doping with Sr on the structure can be properly discussed. Both phase transitions seem to be of first order since they can be associated with discontinuities either in the entropy or in the structure. The first transition (P2/n → Pnma) occurs as the B cations become totally disordered. Along the whole compositional range the modes responsible for the out-of-phase tilting of BO6 octahedra remain active, but those associated with the in-phase octahedral tilting vanish for x ≥ 0.6, this being associated with the second transition (Pnma → R3¯c). Finally, for x = 1.0 the three pseudo-cubic cell parameters become very similar, pointing to a transition to a cubic structure which could be obtained by applying pressure or raising the temperature.
- Published
- 2016
30. The impact of the synthesis conditions on SrAl2O4:Eu, Dy formation for a persistent afterglow
- Author
-
European Commission, Ministerio de Economía y Competitividad (España), Rojas-Hernández, Rocío E., Rubio Marcos, Fernando, Dos Santos Rezende, Marcos Vinícius, Rodríguez Barbero, Miguel Ángel, Serrano Rubio, Aída, Muñoz-Noval, A., Fernández Lozano, José Francisco, European Commission, Ministerio de Economía y Competitividad (España), Rojas-Hernández, Rocío E., Rubio Marcos, Fernando, Dos Santos Rezende, Marcos Vinícius, Rodríguez Barbero, Miguel Ángel, Serrano Rubio, Aída, Muñoz-Noval, A., and Fernández Lozano, José Francisco
- Abstract
The design of phosphorescent materials, highly crystalline, with a submicron particle size is a challenge for industrial applications. Based on molten salt assisted process, the effects of salt/SrAl0 molar ratio on the phase evolution are studied. A significant influence of salt/SrAl0 molar ratio on synthesis and final properties has been observed. Moreover, the phase evolution has been explored as a function of treatment temperature. To remove the salt from the powder, the wash step is carried out with glycerin avoiding hydrolysis reaction due to the sensitivity of strontium aluminates to water. The salt/SrAl0 molar ratio of 3:1 and the thermal treatment at 1000 0C are preferred, avoiding extra wash step. Here, we have obtained highly crystalline SrAl0:Eu, Dy powder with a particle size =0.5 ≤m after a 2 h treatment at 1000 0C employing the molten salt approach. As a result, we believe that the general strategy described in this study opens the possibility of obtaining technologically relevant phosphors with enhanced properties, expanding their application range to radiation detection.
- Published
- 2016
31. Effect of internal pressure and temperature on phase transitions in perovskite oxides: the case of the solid oxide fuel cell cathode materials of the La2-xSrxCoTiO6 series
- Author
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Gómez-Pérez, Alejandro, Hoelzel, Markus, Muñoz-Noval, A., García-Alvarado, Flaviano, Amador, Ulises, Gómez-Pérez, Alejandro, Hoelzel, Markus, Muñoz-Noval, A., García-Alvarado, Flaviano, and Amador, Ulises
- Abstract
The symmetry of the room-temperature (RT) structure of title compounds LaSrCoTiO changes with x, from P2/n (0 ≤ x ≤ 0.2) to Pnma (0.3 ≤ x ≤ 0.5) and to R3;c (0.6 ≤ x ≤ 1). For x = 1 the three pseudocubic cell parameters become very close suggesting a transition to a cubic structure for higher Sr contents. Similar phase transitions were expected to occur on heating, paralleling the effect of internal pressure induced by substitution of La by Sr. However, only some of these aforementioned transitions have been thermally induced. The symmetry-adapted modes formalism is used in the structural refinements and fitting of neutron diffraction data recorded from RT to 1273 K. Thus, for x = 1, the out-of-phase tilting of the BO octahedra vanishes progressively on heating, and a cubic structure with Pm3;m symmetry is found at 1073 K. For lower Sr contents this transition is predicted to occur far above the temperature limit of common experimental setups. The analysis of the evolution of the perovskite tolerance factor, t-factor, with both Sr content and temperature indicates that temperature has a limited ability to release structural stress and thus to enable transitions to more symmetric phases. This is particularly true when compared to the effect of internal pressure induced by substitution of La by Sr. The existence of phase transitions in materials for solid oxide fuel cells that are usually exposed to heating-cooling cycles may have a detrimental effect. This work suggests strategies to stabilize the high-symmetry high-temperature phase of perovskite oxides through internal-pressure chemically induced.
- Published
- 2016
32. Large coincidence lattice on Au/Fe3O4 incommensurate structure for spintronic applications
- Author
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Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), European Commission, Muñoz-Noval, A., Rubio-Zuazo, J., Salas, Eduardo, Serrano Rubio, Aída, Rubio Marcos, Fernando, Castro, Germán R., Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), European Commission, Muñoz-Noval, A., Rubio-Zuazo, J., Salas, Eduardo, Serrano Rubio, Aída, Rubio Marcos, Fernando, and Castro, Germán R.
- Abstract
The design of metallic hybrid systems for spintronics has been widely studied during the past decade, motivated by the promising technological applications of these materials. Nevertheless, the importance of preserving the native structure and properties of the interfaces is often ignored. Here, we present the fabrication of nanocrystalline Au (0 0 1) onto a single oriented Fe3O4 (0 0 1) thin film as a promising hybrid system to develop spintronic devices by growing Au over the Fe3O4 by using a simple one-pot Pulsed Laser Deposition (PLD) approach. The structural coupling between Au nanocrystals and Fe3O4 layer results in the development of an incommensurate structure based on a coincidence lattice of order 35, which preserves the intrinsic properties of the Au nanocrystals, the Fe3O4 matrix and the interface between them. The general strategy described in the present work preserves the structure and main intrinsic properties of the constituting materials, being a fundamental issue for the future development of spintronic devices.
- Published
- 2015
33. Large coincidence lattice on Au/Fe3O4 incommensurate structure for spintronic applications
- Author
-
Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), European Commission, Muñoz-Noval, A., Rubio-Zuazo, J., Salas, Eduardo, Serrano Rubio, Aída, Rubio Marcos, Fernando, Castro, Germán R., Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), European Commission, Muñoz-Noval, A., Rubio-Zuazo, J., Salas, Eduardo, Serrano Rubio, Aída, Rubio Marcos, Fernando, and Castro, Germán R.
- Abstract
The design of metallic hybrid systems for spintronics has been widely studied during the past decade, motivated by the promising technological applications of these materials. Nevertheless, the importance of preserving the native structure and properties of the interfaces is often ignored. Here, we present the fabrication of nanocrystalline Au (0 0 1) onto a single oriented Fe3O4 (0 0 1) thin film as a promising hybrid system to develop spintronic devices by growing Au over the Fe3O4 by using a simple one-pot Pulsed Laser Deposition (PLD) approach. The structural coupling between Au nanocrystals and Fe3O4 layer results in the development of an incommensurate structure based on a coincidence lattice of order 35, which preserves the intrinsic properties of the Au nanocrystals, the Fe3O4 matrix and the interface between them. The general strategy described in the present work preserves the structure and main intrinsic properties of the constituting materials, being a fundamental issue for the future development of spintronic devices.
- Published
- 2015
34. Evidence of a correlation between magnetic and structural transitions in Y2-xZnxRu2O7 pyrochlore compounds
- Author
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Università degli Studi di Milano, Berti, Giulia, Sanna, Samuele, Ruiz-Bustos, Rocío, Van Duijn, Joost, Brambilla, Alberto, Muñoz-Noval, A., Demartin, Francesco, Duò, Lamberto, Castellano, Carlo, Università degli Studi di Milano, Berti, Giulia, Sanna, Samuele, Ruiz-Bustos, Rocío, Van Duijn, Joost, Brambilla, Alberto, Muñoz-Noval, A., Demartin, Francesco, Duò, Lamberto, and Castellano, Carlo
- Abstract
We report on an experimental investigation of the magnetic and structural properties of the YZnRuO pyrochlore system as a function of the Zn doping in the range 0.00 ≤ x ≤ 0.20. Magnetization and muon spin relaxation measurements show that the antiferromagnetic transition typical of the undoped compound at T = 77 K is slightly reduced and broadened in the Zn doped sample. Extended X-ray absorption fine structure measurements show a peak in the Ru-O(1) first shell Debye-Waller factor at a temperature T ≈ T, giving evidence for a strong magnetoelastic coupling detected up to x = 0.10. A local precursor order-disorder transition at T∗ > T is also observed up to x = 0.10. For x > 0.10 these local structural features are hidden due to the increasing local lattice distortion induced by the Zn dopant whereas the magnetic transition is still present.
- Published
- 2015
35. Incommensurate growth of thin and ultrathin films of single-phase Fe3O4(001) on SrTiO3(001)
- Author
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Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), Rubio-Zuazo, J., Onandia, Laura, Salas, Eduardo, Muñoz-Noval, A., Castro, Germán R., Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), Rubio-Zuazo, J., Onandia, Laura, Salas, Eduardo, Muñoz-Noval, A., and Castro, Germán R.
- Abstract
We present structural, electronic, and morphological characterization of thin (7.5 nm, 9 unit cells) and ultrathin (1.7 nm, 2 unit cells) Fe3O4 layers grown on SrTiO3(001) by oxygen assisted molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) methods. The analysis show single-phase single oriented (001) layers that grow forming a coincidence lattice of the order 13. Such an incommensurate growth is present for all the layers, independent of the evaporation method and layer thickness. The magnetite layers, which are strain-free, provide a sharp interface with the substrate. The films grown by the MBE method present negligible interaction with the substrate and smooth surfaces. The films grown by the PLD evaporation method present an expansion of the last atomic layer of the substrate and rough layer surface. However, the obtained structural domain size of 10 nm is identical for the layers grown by both evaporation techniques corresponding to the size of the coincidence lattice. We determine that the magnetic and transport properties inherent to the Fe3O4/ STO heterostructure are not related to the lattice strain but to the formation of antiphase boundary defects.
- Published
- 2015
36. Luminescence and fine structure correlation in ZnO permeated porous silicon nanocomposites
- Author
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Ministerio de Economía y Competitividad (España), Gallach, D., Muñoz-Noval, A., Torres-Costa, Vicente, Manso-Silván, Miguel, Ministerio de Economía y Competitividad (España), Gallach, D., Muñoz-Noval, A., Torres-Costa, Vicente, and Manso-Silván, Miguel
- Abstract
Nanocomposites formed by porous silicon (PS) and zinc oxide (ZnO) have potential for applications in optoelectronic devices. However, understanding the distribution of both materials in the nanocomposite, and especially the fine structure of the synthesized ZnO crystals, is key for future device fabrication. This study focuses on the advanced characterization of a range of PS–ZnO nanocomposites by using photon- and ion-based techniques, such as X-ray absorption spectroscopy (XAS) and elastic backscattering spectroscopy (EBS), respectively. PS substrates formed by the electrochemical etching of p+-type Si are used as host material for the sol–gel nucleation of ZnO nanoparticles. Different properties are induced by annealing in air at temperatures ranging from 200 °C to 800 °C. Results show that wurtzite ZnO nanoparticles form only at temperatures above 200 °C, coexisting with Si quantum dots (QDs) inside a PS matrix. Increasing the annealing temperature leads to structural and distribution changes that affect the electronic and local structure of the samples changing their luminescence. Temperatures around 800 °C activate the formation of a new zinc silicate phase and transform PS into an amorphous silicon oxide (SiOx, x ≈ 2) matrix with a noticeably reduced presence of Si QDs. Thus, these changes affect dramatically the emission from these nanocomposites and their potential applications.
- Published
- 2015
37. Design and development of a controlled pressure/temperature set-up for in situ studies of solid–gas processes and reactions in a synchrotron X-ray powder diffraction station
- Author
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Ministerio de Economía y Competitividad (España), Salas, Eduardo, Muñoz-Noval, A., Heyman, C., Ovín Ania, María Concepción, Parra Soto, José Bernardo, García-Granda, Santiago, Calero, S., Rubio-Zuazo, J., Castro, Germán R., Ministerio de Economía y Competitividad (España), Salas, Eduardo, Muñoz-Noval, A., Heyman, C., Ovín Ania, María Concepción, Parra Soto, José Bernardo, García-Granda, Santiago, Calero, S., Rubio-Zuazo, J., and Castro, Germán R.
- Abstract
A novel set-up has been designed and used for synchrotron radiation X-ray high-resolution powder diffraction (SR-HRPD) in transmission geometry (spinning capillary) for in situ solid–gas reactions and processes in an isobaric and isothermal environment. The pressure and temperature of the sample are controlled from 10−3 to 1000 mbar and from 80 to 1000 K, respectively. To test the capacities of this novel experimental set-up, structure deformation in the porous material zeolitic imidazole framework (ZIF-8) by gas adsorption at cryogenic temperature has been studied under isothermal and isobaric conditions. Direct structure deformations by the adsorption of Ar and N2 gases have been observed in situ, demonstrating that this set-up is perfectly suitable for direct structural analysis under in operando conditions. The presented results prove the feasibility of this novel experimental station for the characterization in real time of solid–gas reactions and other solid–gas processes by SR-HRPD.
- Published
- 2015
38. Photoassisted immersion deposition of cu clusters onto porous silicon: a Langmuir-Hill Ligand-locus model applied to the growth kinetics
- Author
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Recio-Sánchez, Gonzalo, Gallach, Dario, Manso-Silván, Miguel, Fukami, Kazuhiro, Martín Palma, Raúl José, Castro, Germán R., Muñoz-Noval, A., Recio-Sánchez, Gonzalo, Gallach, Dario, Manso-Silván, Miguel, Fukami, Kazuhiro, Martín Palma, Raúl José, Castro, Germán R., and Muñoz-Noval, A.
- Abstract
Cu-porous silicon (Cu-PS) composite materials consisting of nanosized Cu clusters preferentially grown on the surface of PS were fabricated by photoassisted deposition of Cu nanoparticles onto PS. Structural and chemical characterization of the Cu particles grown in the PS matrix has been carried out by synchrotron X-ray absorption spectroscopy, from which different reaction stages have been identified within the photoassisted reaction. In particular, it was found that the reduction of Cu occurs in three main phases: (a) Cu nucleates homogeneously in a few seconds over the surface of PS by a coupled red-ox reaction; (b) clusters grow by new reduced ions, which tend to oxidize the previously deposited Cu atoms making increasingly heterogeneous Cu clusters; and (c) a competitive process between nucleation of new clusters and cluster coalescence gives rise to a bulklike Cu thin film. It was determined that the structures formed in the first two phases display surface plasmon resonance, with band intensity and broadening consistent with the increasing heterogeneity of the clusters. The growth kinetics has been fitted to a Langmuir-Hill model. Following these results, a reaction model has been proposed to explain the mechanisms involved in the first stages of Cu clustering.
- Published
- 2014
39. Sharp chemical interface in epitaxial Fe3O4 thin films
- Author
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Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), Gálvez, S., Rubio-Zuazo, J., Salas, Eduardo, Muñoz-Noval, A., Castro, Germán R., Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), Gálvez, S., Rubio-Zuazo, J., Salas, Eduardo, Muñoz-Noval, A., and Castro, Germán R.
- Abstract
Chemically sharp interface was obtained on single phase single oriented Fe3O4 (001) thin film (7 nm) grown on NiO (001) substrate using oxygen assisted molecular beam epitaxy. Refinement of the atomic structure, stoichiometry, and oxygen vacancies were determined by soft and hard x-ray photoelectron spectroscopy, low energy electron diffraction and synchrotron based X-ray reflectivity, and X-ray diffraction. Our results demonstrate an epitaxial growth of the magnetite layer, perfect iron stoichiometry, absence of oxygen vacancies, and the existence of an intermixing free interface. Consistent magnetic and electrical characterizations are also shown.
- Published
- 2014
40. Analysis of the distribution of Tm3+ ions in LaF3 containing transparent glass-ceramics through X-ray absorption spectroscopy
- Author
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Comisión Interministerial de Ciencia y Tecnología, CICYT (España), Consejo Superior de Investigaciones Científicas (España), European Commission, Pablos Martín, Araceli de, García García-Tuñón, Miguel Ángel, Muñoz-Noval, A., Castro, Germán R., Pascual, M. Jesús, Durán, Alicia, Comisión Interministerial de Ciencia y Tecnología, CICYT (España), Consejo Superior de Investigaciones Científicas (España), European Commission, Pablos Martín, Araceli de, García García-Tuñón, Miguel Ángel, Muñoz-Noval, A., Castro, Germán R., Pascual, M. Jesús, and Durán, Alicia
- Abstract
Incorporation of rare-earth (RE) ions in the fluoride crystals of oxyfluoride glass-ceramics greatly improves the optical properties of these materials, such as the up-conversion emission. In this work, we present a study of this incorporation using X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. Both techniques allow quantifying the distribution of these ions in the glass matrix and the fluoride crystals. We found that 27% of Tm3 + ions are incorporated in LaF3 nano-crystals. © 2013 Elsevier B.V.
- Published
- 2014
41. A comparative analysis of visual strategy in elite and amateur handball goalkeepers
- Author
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Rivilla García, Jesús, Muñoz Noval, Alejandro, Grande Rodriguez, Ignacio, Sanchís Almenara, Mercedes, Sampedro Molinuevo, Javier, Rivilla García, Jesús, Muñoz Noval, Alejandro, Grande Rodriguez, Ignacio, Sanchís Almenara, Mercedes, and Sampedro Molinuevo, Javier
- Abstract
The aim of the present study was to analyze the visual strategies prior to a throw from 7 metres in elite and amateur handball goalkeepers. To this end we analyzed the visual fixations in number and order of 10 goalkeepers (29.7±5.4 years; 14.7±8.6 years of experience), 3 elite and 7 amateurs, during the life size projection of 14 different throws, made by different players. During each throw the movement of the eyeballs, the dilation of the pupil (pupillometry) and the subject?s blinking were recorded thanks to a technological system which permitted eye tracking with high speed cameras, and the subsequent presentation of the visual data for each action studied. The elite goalkeepers performed a greater number of visual fixations than the amateur goalkeepers, revealing large and significant differences. Equally the priority zones observed were differed, with the amateur goalkeepers fixating more on the thrower?s face, and the elite goalkeepers paying more attention to the area of the arm/ball. It can therefore be inferred that elite goalkeepers have a greater perceptive capacity and also use different visual strategies from the amateur goalkeepers.
- Published
- 2013
42. Design and characterization of biofunctional magnetic porous silicon flakes
- Author
-
Muñoz Noval A., García R., Ruiz Casas D., Losada Bayo D., Sánchez Vaquero V., Torres Costa V., Martín Palma R.J., García M.A., García Ruiz J.P., Serrano Olmedo J.J., Muñoz Negrete J.F., Del Pozo Guerrero F., Manso Silván M., Muñoz Noval A., García R., Ruiz Casas D., Losada Bayo D., Sánchez Vaquero V., Torres Costa V., Martín Palma R.J., García M.A., García Ruiz J.P., Serrano Olmedo J.J., Muñoz Negrete J.F., Del Pozo Guerrero F., and Manso Silván M.
- Published
- 2013
43. A comparative analysis of visual strategy in elite and amateur handball goalkeepers
- Author
-
Rivilla García, Jesús, Muñoz Noval, Alejandro, Grande Rodriguez, Ignacio, Sanchís Almenara, Mercedes, Sampedro Molinuevo, Javier, Rivilla García, Jesús, Muñoz Noval, Alejandro, Grande Rodriguez, Ignacio, Sanchís Almenara, Mercedes, and Sampedro Molinuevo, Javier
- Abstract
The aim of the present study was to analyze the visual strategies prior to a throw from 7 metres in elite and amateur handball goalkeepers. To this end we analyzed the visual fixations in number and order of 10 goalkeepers (29.7±5.4 years; 14.7±8.6 years of experience), 3 elite and 7 amateurs, during the life size projection of 14 different throws, made by different players. During each throw the movement of the eyeballs, the dilation of the pupil (pupillometry) and the subject?s blinking were recorded thanks to a technological system which permitted eye tracking with high speed cameras, and the subsequent presentation of the visual data for each action studied. The elite goalkeepers performed a greater number of visual fixations than the amateur goalkeepers, revealing large and significant differences. Equally the priority zones observed were differed, with the amateur goalkeepers fixating more on the thrower?s face, and the elite goalkeepers paying more attention to the area of the arm/ball. It can therefore be inferred that elite goalkeepers have a greater perceptive capacity and also use different visual strategies from the amateur goalkeepers.
- Published
- 2013
44. Design and characterization of biofunctional magnetic porous silicon flakes
- Author
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Ministerio de Ciencia e Innovación (España), Comunidad de Madrid, Muñoz-Noval, A., García, R., Ruiz Casas, D., Losada Bayo, D., Sánchez Vaquero, V., Torres-Costa, Vicente, Martín-Palma, Raúl J., García García-Tuñón, Miguel Ángel, García Ruiz, J. P., Serrano Olmedo, J. J., Muñoz Negrete, J. F., del Pozo Guerrero, F., Manso-Silván, Miguel, Ministerio de Ciencia e Innovación (España), Comunidad de Madrid, Muñoz-Noval, A., García, R., Ruiz Casas, D., Losada Bayo, D., Sánchez Vaquero, V., Torres-Costa, Vicente, Martín-Palma, Raúl J., García García-Tuñón, Miguel Ángel, García Ruiz, J. P., Serrano Olmedo, J. J., Muñoz Negrete, J. F., del Pozo Guerrero, F., and Manso-Silván, Miguel
- Abstract
Magnetic porous silicon flakes (MPSF) were obtained from mesoporous silicon layers formed by multi-step anodization and subsequent composite formation with Fe oxide nanoparticles by thermal annealing. The magnetic nanoparticles adhered to the surface and penetrated inside the pores. Their structure evolved as a result of the annealing treatments derived from X-ray diffraction and X-ray absorption analyses. Moreover, by tailoring the magnetic load, the dynamic and hydrodynamic properties of the particles were controlled, as observed by the pressure displayed against a sensor probe. Preliminary functionality experiments were performed using an eye model, seeking potential use of MPSF as reinforcement for restored detached retina. It was observed that optimal flake immobilization is obtained when the MPSF reach values of magnetic saturation >10-4 A m2 g-1. Furthermore, the MPSF were demonstrated to be preliminarily biocompatible in vitro. Moreover, New Zealand rabbit in vivo models demonstrated their short-term histocompatibility and their magnetic functionality as retina pressure actuators.
- Published
- 2013
45. Magnetic and electronic properties of bimagnetic materials comprising cobalt particles within hollow silica decorated with magnetite nanoparticles
- Author
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Okada, T., González-Alfaro, Y., Espinosa, A., Muñoz-Noval, A., Aranda, Pilar, García-Hernández, Mar, Ruiz-Hitzky, Eduardo, Okada, T., González-Alfaro, Y., Espinosa, A., Muñoz-Noval, A., Aranda, Pilar, García-Hernández, Mar, and Ruiz-Hitzky, Eduardo
- Abstract
Bimagnetic materials were fabricated by decorating the external surface of rattle-type hollow silica microspheres (which themselves contain metallic cobalt nanoparticles) with magnetite nanoparticles; thus, each magnetic substance was spatially isolated by the silica shell. The amount of magnetite decoration on the co-occluded hollow silica was varied from 1 to 17 mass %. Magnetic and electronic properties of the resulting bimagnetic materials were characterized by superconducting quantum interference device measurements and X-ray absorption spectroscopy, respectively. The ferrous iron in the bimagnetic sample was slightly more oxidized than in the magnetite reference, probably from some charge-transfer because of the SiO2 surface contact, although the overall oxidation state of the samples is very similar to that of magnetite. The temperature dependence of the sample magnetization recorded with Zero Field Cooling and Field Cooling resulted in blocking temperatures for the bimagnetic materials that were close to that of magnetite nanoparticles (176 K) and were lower than that for the bare Co-occluded hollow silica (which was above room temperature). Values of coercive force and exchange bias at 300 K became quite small after decoration with only minimal amounts of magnetite nanoparticles (1-3 mass %) and were lower than those of magnetite. This is the first example of enhancing superparamagnetism by spatial separation of both Co and magnetite magnetic nanoparticles using a thin wall of diamagnetic silica. © 2013 AIP Publishing LLC.
- Published
- 2013
46. Magnetic properties of iron oxide nanoparticles prepared by seeded-growth route
- Author
-
Ministerio de Economía y Competitividad (España), European Commission, Comunidad de Madrid, Espinosa, Ana, Muñoz-Noval, A., García-Hernández, Mar, Serrano Rubio, Aída, Jiménez de la Morena, J., García García-Tuñón, Miguel Ángel, Ministerio de Economía y Competitividad (España), European Commission, Comunidad de Madrid, Espinosa, Ana, Muñoz-Noval, A., García-Hernández, Mar, Serrano Rubio, Aída, Jiménez de la Morena, J., and García García-Tuñón, Miguel Ángel
- Abstract
In this work we investigate the magnetic properties of iron oxide nanoparticles obtained by two-step synthesis (seeded-growth route) with sizes that range from 6 to 18 nm. The initial seeds result monocrystalline and exhibit ferromagnetic behavior with low saturation field. The subsequent growth of a shell enhances the anisotropy inducing magnetic frustration, and, consequently, reducing its magnetization. This increase in anisotropy occurs suddenly at a certain size (~10 nm). Electronic and structural analysis with X-ray absorption spectroscopy indicates a step reduction in the oxidation state as the particle reaches 10 nm size while keeping its overall structure in spite of the magnetic polydispersity. The formation of antiphase magnetic boundaries due to island percolation in the growing shells is hypothesized to be the mechanism responsible of the magnetic behavior, as a direct consequence of the two-step synthesis route of the nanoparticles.
- Published
- 2013
47. Electroless nanoworm Au films on columnar porous silicon layers
- Author
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Muñoz-Noval Á., Torres-Costa V., Martín-Palma R.J., Herrero-Fernández P., García M.Á., Fukami K., Ogata Y.H., Silván M.M., Muñoz-Noval Á., Torres-Costa V., Martín-Palma R.J., Herrero-Fernández P., García M.Á., Fukami K., Ogata Y.H., and Silván M.M.
- Published
- 2012
48. Characterization of hybrid cobalt-porous silicon systems: protective effect of the Matrix in the metal oxidation
- Author
-
Ministerio de Educación y Ciencia (España), Consejo Superior de Investigaciones Científicas (España), Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Commission, Muñoz-Noval, A., García García-Tuñón, Miguel Ángel, Herrero, Pilar, Fukami, Kazuhiro, Ogata, Yukio H., Torres-Costa, Vicente, Martín-Palma, Raúl J., Climent-Font, A., Manso-Silván, Miguel, Ministerio de Educación y Ciencia (España), Consejo Superior de Investigaciones Científicas (España), Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Commission, Muñoz-Noval, A., García García-Tuñón, Miguel Ángel, Herrero, Pilar, Fukami, Kazuhiro, Ogata, Yukio H., Torres-Costa, Vicente, Martín-Palma, Raúl J., Climent-Font, A., and Manso-Silván, Miguel
- Abstract
In the present work, the characterization of cobalt-porous silicon (Co-PSi) hybrid systems is performed by a combination of magnetic, spectroscopic, and structural techniques. The Co-PSi structures are composed by a columnar matrix of PSi with Co nanoparticles embedded inside, as determined by Transmission Electron Microscopy (TEM). The oxidation state, crystalline structure, and magnetic behavior are determined by X-Ray Absorption Spectroscopy (XAS) and Alternating Gradient Field Magnetometry (AGFM). Additionally, the Co concentration profile inside the matrix has been studied by Rutherford Backscattering Spectroscopy (RBS). It is concluded that the PSi matrix can be tailored to provide the Co nanoparticles with extra protection against oxidation.
- Published
- 2012
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