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Autor Crespo del Arco, Patricia |
Documentos disponibles escritos por este autor (39)
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Marín Palacios, Pilar ; Aragon, A.M ; Lieblich, M. ; Garcia Escorial, A. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio | American Institute of Physics | 2012-07Magnetization curves of mixed Nb and FeSi based micrometric particles have been analyzed. The influence of the dispersion of Nb particles on the mixture remanence and coercivity has been studied above and below the Nb superconducting critical t[...]texto impreso
Marín Palacios, María Pilar ; Aragón, A. M ; Garcia Escoria, A. ; Lieblich, M. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio | American Institute of Physics | 2013-01-28Fe_(73.5)Si_(13.5)B_9Nb_3Cu_1 powder particles have been obtained by gas atomization. Magnetization curves and coercivity were studied for particles ranging in size up to 1000?. The overall magnetic behavior of such material is consequence of c[...]texto impreso
Galindo, R. ; Menendez, N. ; Crespo del Arco, Patricia ; Velasco, V. ; Bomati Miguel, O. ; Díaz Fernández, D. ; Herrasti, P. | Elsevier Science BV | 2014-06Nickel nanoferrites were obtained by means of four different synthetic wet-routes: co-precipitation (CP), sonochemistry (SC), sonoelectrochemistry (SE) and electrochemistry (E). The influence of the synthesis method on the structural and magneti[...]texto impreso
Martínez, A. ; Spottorno Giner, Jorge ; Figueroa, A. ; Bartolome, F. ; Garcia, L. M. ; Prestipino, C. ; Hernando Grande, Antonio ; Crespo del Arco, Patricia | American Physical Society | 2010-07-14Amorphous metastable alloy of nominal composition [Fe_(0.5)Cu_(0.5)]_(87)Zr_(13) has been synthesized by high-energy ball milling. The alloy exhibit a ferromagnetic behavior with a Curie Temperature of T_(C)=255 K, as determined from low-field m[...]texto impreso
Navarro, I. ; Pulido, E. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio | American Institute of Physics | 1993-03-15It is shown that the presence of highly anisotropic magnetic precipitates in a soft multiphased matrix can produce a remarkable hardening, even when the volume fraction of the precipitates is small. The exchange coupling between the matrix and t[...]texto impreso
Guerrero, Estefania ; Muñoz Márquez, Miguel ; Fernández Pinel, Enrique ; Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Fernández, Asunción | Springer | 2008Gold nanoparticles (NPs) have been stabilized with a variety of thiol-containing molecules in order to change their chemical and physical properties; among the possible capping systems, alkane chains with different lengths, a carboxylic acid and[...]texto impreso
Hernando Grande, Antonio ; Crespo del Arco, Patricia ; García, M. A. | American Physical Society | 2006-03-03texto impreso
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Guerrero, E. ; Rojas, T. C ; Multigner, M. ; Crespo del Arco, Patricia ; Muñoz Márquez, M. A. ; García, M. A. ; Hernando Grande, Antonio ; Fernández, A. | Pergamon-Elsevier Science Ltd | 2007-03In the present paper, we show an exhaustive microstructural characterization of thiol-capped gold nanoparticles (NPs) with two different average particle sizes. These samples are compared with the polymer-like Au(I) phase formed as a precursor d[...]texto impreso
Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Garcia Escorial, A. ; Kemner, K.M. ; Harris, V. J. | American Institute of Physics | 1994-11-15The local structure and chemistry of a ferromagnetic fcc-Fe_50Cu_50 solid solution obtained through high-energy ball milling were measured before and after heat-treatment-induced decomposition using extended x-ray-absorption fine-structure measu[...]texto impreso
Crespo del Arco, Patricia ; García, M. A. ; Fernandez Pinel, E. ; Multigner, M. ; Alcántara, D. ; De la Fuente, J. M. ; Penadés, S. ; Hernando Grande, Antonio | American Physical Society | 2006-10-27In this Letter, we report on a crucial experiment showing that magnetic impurities reduce the ferromagnetic order temperature in thiol-capped Au glyconanoparticles (GNPs). The spontaneous magnetization of AuFe GNPs exhibits a fast decrease with [...]texto impreso
Sampedro, B. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Litran, R. ; Sánchez López, J. C. ; López Cartes, C. ; Fernández, A. ; Ramírez, J. ; Gónzalez Calbet, J. ; Vallet, M. | American Physical Society | 2003-12-05The onset of ferromagnetism has been experimentally observed in small Pd particles of average diameter 2.4 nm. High-resolution studies reveal that a high percentage of the fcc particle exhibits single and multiple twinning boundaries. The sponta[...]texto impreso
Crespo del Arco, Patricia ; Multigner, M. ; Castaño, F. J. ; Casero, R. ; Hernando Grande, Antonio | American Physical Society | 2000-06-01In this paper, the production of FeCu-based FeCuZr amorphous alloys by ball milling is reported. The thermal dependence of magnetization for the [Fe_(0.5)Cu_(0.5)]_85Zr_(15) (at. %) amorphous alloy has been found to show a dramatic field depende[...]texto impreso
Hernando Grande, Antonio ; Ayuela, A. ; Crespo del Arco, Patricia ; Echenique, P. M. | IOP Publishing | 2014The presence of giant diamagnetism in Au nanorods, NRs, is shown to be a possible consequence of field induced currents in the surface electrons. The distance, ?, between quantum surface energy levels has been calculated as a function of the NRs[...]texto impreso
Hernando Grande, Antonio ; Crespo del Arco, Patricia ; García, M. A. ; Fernandez Pinel, E. ; De la Venta,1, J ; Fernández, A. ; Penadés, S. | American Physical Society | 2006-08It has been observed for palladium and gold nanoparticles that the magnetic moment at a constant applied field does not change with temperature over the range comprised between 5 and 300 K. These samples, with sizes smaller than 2.5 nm, exhibit [...]texto impreso
Crespo del Arco, Patricia ; Marín, P. ; Hernando Grande, Antonio | American Institute of Physics | 2000-05-01We present experimental results on the hysteresis and relaxation of Fe/Ba hexaferrite composite samples prepared by ball milling starting from precursor Fe and Ba hexaferrite particles. Our results show that, for maximum applied fields of up to [...]texto impreso
Prados, C. ; Crespo del Arco, Patricia ; González, J. M. ; Hernando Grande, Antonio ; Marcos, J. F. ; Gancedo, R. ; Grobert, N. ; Terrones, M. ; Walton, R. M. ; Kroto, H. W. | American Physical Society | 2002-03-15The phase distribution of high aspect ratio, Fe-filled carbon nanotubes prepared by pyrolyzing a mixture of powered ferrocene and C_(60) has been determined by means of Mössbauer spectroscopy. Our results for that characterization are closely re[...]texto impreso
Litran, R. ; Sampedro, B. ; Rojas,, T. C. ; Multigner, M. ; Sánchez López, J. C. ; Crespo del Arco, Patricia ; López Cartes, C. ; García, M. A. ; Hernando Grande, Antonio ; Fernández, A. | American Physical Society | 2006-02Palladium nanoparticles capped with different protective systems in a size range between 1.2 and 2.4 nm have been obtained by varying the preparation chemical method. Magnetization curves for all the samples show hysteresis loops, evidencing a f[...]texto impreso
Rivero, G. ; Crespo del Arco, Patricia ; Pulido, E ; Garcia-Escorial, A. ; Hernando Grande, Antonio ; Vázquez, M. ; Vallet, M. ; Gonzalez-Calbet, J. | American Institute of Physics | 1991-04-15The specific magnetic moment, coercive force, anisotropy field, and saturation magnetostriction constant have been measured in Co(1-x)P(x) amorphous ribbons with 0.04 less-than-or-equal-to x less-than-or-equal-to 0.27. Differential scanning calo[...]texto impreso
Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Yavari, R ; Drbohlav, O. ; Garcia Escorial, A. ; Barandiaran, J. M. ; Orue, I. | American Physical Society | 1993-09-01A ferromagnetic and supersaturated fcc Fe_51Cu_49 solid solution has been obtained by mechanical alloying. After subsequent thermal treatments the fcc phase undergoes a spinodal decomposition which finally, at 780 K, yields a mixture of fcc and [...]texto impreso
Garcia, N. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Bovier, C. ; Serughetti, J. ; Bovier, C. ; Duval, E. | American Physical Society | 1993-01-01We have studied the magnetic properties of Cu-doped porous silica gels and found that the system seems to be ferromagnetic up to room temperature. This result is fascinating because the amount of Cu ranges from 0.15% to 3% in weight of the total[...]texto impreso
De la Venta, J. ; Fernandez Pinel, E. ; García, M. A. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Rodríguez de la Fuente, Óscar ; De Julián Fernández, C ; Fernández, A ; Penadés, S. | World Scientific Publ Co Pte Ltd | 2007-03-10We review here our recent results of experimental observation of room temperature magnetism in gold nanoparticles (NPs) and thin. films. Capping gold surfaces with certain organic molecules leads to the appearance of magnetism at room temperatur[...]texto impreso
Garcia, M.A. ; Fernandez Pinel, E. ; Quesada, A. ; De la Venta, M. L. ; Crespo del Arco, Patricia ; LLopis, J. ; Hernando Grande, Antonio | Amer Chemical Soc | 2007-06We experimentally show that it is possible to induce room-temperature ferromagnetic-like behavior in ZnO nanoparticles without doping with magnetic impurities but simply inducing an alteration of their electronic configuration. Capping ZnO nanop[...]texto impreso
Guerrero, E. ; Munoz-Marquez, M. A. ; Fernández, A. ; Crespo del Arco, Patricia ; Hernando, A. ; Lucena, R. ; Conesa, J. C. | American Institute of Physics | 2010-03-15In the last years, the number of studies performed by wholly independent research groups that confirm the permanent magnetism, first observed in our research lab, for thiol-capped Au nanoparticles (NPs) has rapidly increased. Throughout the year[...]texto impreso
Harris, V. G. ; Das,, B.N. ; Woicik, J. C. ; Crespo del Arco, Patricia ; Hemando, A. ; Garcia Escorial, A. | Editions Physique | 1997-04A least-square fitting analysis of EXAFS data collected from partially-crystallized Fe_80B_20 thin films (t=15 nm), using data collected from pure phase standards of the crystallization products, was found effective in determining the relative a[...]texto impreso
Hernando Grande, Antonio ; Crespo del Arco, Patricia ; Escorial Garcia, A. ; Barandiaran, J. M. | American Physical Society | 1993-05-31In conclusion we have proven that the fact that both fcc FeCu and bcc Fe magnetization agree at 300 K is simply an accident and our data at low temperature show clearly that the Fe contribution after precipitation from the metastable phase has a[...]texto impreso
Hernando Grande, Antonio ; Crespo del Arco, Patricia ; García, M. A. | Hindawi Publishing Corporation | 2005-12In this paper, we reviewed some relevant aspects of the magnetic properties of metallic nanoparticles with small size ( below 4 nm), covering the size effects in nanoparticles of magnetic materials, as well as the appearance of magnetism at the[...]texto impreso
Kirkland, J. P. ; Woicik, J. C. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Garcia Escorial, A. | American Physical Society | 1996-08-01Extended x-ray-absorption fine-structure (EXAFS) measurements were used to obtain element- specific, structural, and chemical information of the local environments around Cu and Fe atoms in high-energy ballmilled Cu_Fe_(12-X) samples (x=0.50 and[...]texto impreso
Hernando Grande, Antonio ; Crespo del Arco, Patricia ; Garcia, M.A. | American Physical Society | 2006-02-10The origin of orbital magnetism recently observed in different nanostructured films and particles is discussed as a consequence of spin-orbit coupling. It is shown that contact potentials induced at the thin film surface by broken symmetries, as[...]texto impreso
Presa Muñoz del Toro, Patricia de la ; Luengo, Y. ; Velasco, V. ; Morales, P. M. ; Iglesias, M. ; Veintemillas-Verdaguer, S. ; Crespo del Arco, Patricia ; Hernando Grande, Antonio | Amer Chemical Soc | 2015-05-21The influence of magnetic interactions in assemblies formed by either aggregated or disaggregated uniform gamma-Fe_2O_3 particles are investigated as a function of particle size, concentration, and applied field. Hyperthermia and magnetization m[...]texto impreso
Crespo del Arco, Patricia ; Litran, R. ; Rojas, T. C. ; Multigner, M. ; De la Fuente, J. M. ; Sánchez López, J. C. ; García, M. A. ; Hernando Grande, Antonio ; Penadés, S. ; Fernández, A. | American Physical Society | 2004-08-20We report on the experimental observation of magnetic hysteresis up to room temperature in thiol-capped Au nanoparticles with 1.4 nm size. The coercive field ranges from 860 Oe at 5 K to 250 Oe at 300 K. It is estimated that the Au atoms exhibit[...]texto impreso
Martínez, A ; Romero, J.J. ; Bartolome, F. ; Garcia, L.M. ; Baudelet, F. ; Hernando Grande, Antonio ; Crespo del Arco, Patricia | Amer Inst Physics | 2012-07-02The room temperature changes of the magnetic behavior under pressure of an invar alloy of nominal composition [Fe_(0.5)Cu_(0.5)]_(87)Zr_(13) (at. %) has been studied by K-edge x-ray magnetic circular dichroism (XMCD) and x-ray absorption near e[...]texto impreso
Ayuela, A. ; Crespo del Arco, Patricia ; Garcia, M.A. ; Hernando Grande, Antonio ; Echenique, P. M. | IOP Publishing | 2012-01-31Using first-principles calculations, we consider the bond between thiolate and small Au clusters, with particular emphasis on the resulting magnetic moment. The moment of pure gold clusters is 1 mu(B) for clusters with an odd number of Au atoms [...]texto impreso
Crespo del Arco, Patricia ; González, J. M. ; Hernando Grande, Antonio ; Ynduráin, F. J. | American Physical Society | 2004-01It has been found that in highly anisometric ribbon-shaped Fe particles with nanoscale dimensions that the magnetization decreases with temperature markedly faster than in bulk bcc Fe. This anomalous dependence, which becomes more remarkable as [...]texto impreso
Crespo del Arco, Patricia ; Hernando Grande, Antonio ; Garcia Escorial, A. | American Institute of Physics | 1994-05-01Experimental results corresponding to the saturation magnetization and coercive field during the decomposition, upon annealing, of bcc and fcc Fe_xCu_(1-x), obtained by mechanical alloying are reported. The overall behavior points out that the d[...]texto impreso
Guerrero, E. ; Muñoz Márquez, M. A. ; García, M. A. ; Crespo del Arco, Patricia ; Fernandez Pinel, E. ; Hernando Grande, Antonio ; Fernández, A. | IOP publishing ltd | 2008-04-30Surface plasmon resonance measurements and magnetic characterization studies have been carried out for two types of thiol-capped gold nanoparticles (NPs) with similar diameters between 2.0 and 2.5 nm and different organic molecules linked to the[...]texto impreso
García, M. A. ; De la Venta, J ; Crespo del Arco, Patricia ; LLopis,, J. ; Penadés, S. ; Fernández, A. ; Hernando Grande, Antonio | American Physical Society | 2005-12In this Rapid Communication we show the relationship between surface plasmon resonance damping and the intensity of surface bonding for capped Au nanoparticles, (NPs). Up to now the influence of capping has been included as a phenomenological mo[...]texto impreso
Hernando Grande, Antonio ; Crespo del Arco, Patricia ; Castaño, F. J. ; Arcas, J. ; Multigner, M. ; Barandiaran, J. M. ; Fernández Barquín, L. | American Physical Society | 2000-01-01We report the existence of a thermally induced sharp increase of thermoremanence around the Curie temperature of Invar-like Fe-Zr(B,Cu) soft magnetic glasses. Neutron-diffraction measurements indicate that a true enhancement of the average local[...]texto impreso
Magnetism of capped nanoparticles, NPs, of non- magnetic substances as Au and ZnO is briefly reviewed. The source of the magnetization is discussed on the light of recent X-ray magnetic circular dichroism experiments. As magnetic dichroism analy[...]