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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

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

Generation, manipulation, and sensing of magnetic domain walls are cornerstones in the design of efficient spintronic devices. Half-metals are amenable for this purpose as large low field magnetoresistance signals can be expected from spin accumulation at spin textures. Among half metals, La1−xSrxMnO3 (LSMO) manganites are considered as promising candidates for their robust half-metallic ground state, Curie temperature above room temperature (Tc = 360 K, for x = 1/3), and chemical stability. Yet domain wall magnetoresistance is poorly understood, with large discrepancies in the reported values and conflicting interpretation of experimental data due to the entanglement of various source of magnetoresistance, namely, spin accumulation, anisotropic magnetoresistance, and colossal magnetoresistance. In this work, the domain wall magnetoresistance is measured in LSMO cross-shape nanowires with single-domain walls nucleated across the current path. Magnetoresistance values above 10% are found to be originating at the spin accumulation caused by the mistracking effect of the spin texture of the domain wall by the conduction electrons. Fundamentally, this result shows the importance on non-adiabatic processes at spin textures despite the strong Hund coupling to the localized t2g electrons of the manganite. These large magnetoresistance values are high enough for encoding and reading magnetic bits in future oxide spintronic sensors., Unión Europea Horizonte 2020, Comunidad Autónoma de Madrid, Gobierno de España, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Using X-ray absorption spectroscopy and electron energy loss spectroscopy with atomic-scale spatial resolution, experimental evidence for charge transfer at the interface between the Mott insulators Sm2CuO4 and LaFeO3 is obtained. As a consequence of the charge transfer, the Sm2CuO4 is doped with electrons and thus epitaxial Sm2CuO4/LaFeO3 heterostructures become metallic., Ministerio de Ciencia e Innovación (España), Comunidad de Madrid, Unión Europea. FP7, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Direct evidence for charge leakage at the interface of epitaxial SrTiO3/LaMnO3 superlattices with atomically sharp interfaces is provided. The direction of charge leakage can be reversed by changing the LMO/STO thickness ratio. This result will be important for the understanding of some of the reported limitations of oxide devices involving manganite/titanate interfaces., Ministerio de Ciencia e Innovación (España), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2011 American Physical Society. Este artículo está firmado por 13 autores. Work at UCM was supported by Spanish MICINN Grant No. MAT 2008 06517, Consolider Ingenio CSD2009- 00013 (IMAGINE), and CAM S2009-MAT 1756 (PHAMA). Work at ORNL was supported by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy. M. V. acknowledges ERC starting Grant No. 239739 STEMOX., We report on the magnetic coupling of La_(0.7)Sr_(0.3)MnO_(3) layers through SrTiO_(3) spacers in La_(0.7)Sr_(0.3)MnO_(3)/SrTiO_(3) epitaxial heterostructures. Combined aberration-corrected microscopy and electron-energy-loss spectroscopy evidence charge transfer to the empty conduction band of the titanate. Ti d electrons interact via superexchange with Mn, giving rise to a Ti magnetic moment as demonstrated by x-ray magnetic circular dichroism. This induced magnetic moment in the SrTiO_(3) controls the bulk magnetic and transport properties of the superlattices when the titanate layer thickness is below 1 nm., Spanish MICINN, CAM, Materials Sciences and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy, ERC, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2008 American Institute of Physics. The work at UCM was supported by MEC MAT 2005—06024 C02 and work at UMN was supported by NSF DMR., Electrical transport properties of heteroepitaxial p-n junctions made of La_(0.8)Sr_(0.2)CoO_(3) and SrTi_(0.99)Nb_(0.01)O_(3) were studied. Junctions display highly rectifying current-voltage characteristics over a wide temperature range (20–300 K). Two distinct transport mechanisms are identified: tunneling assisted by interface states at T<130 K and diffusion/recombination at higher temperatures. Capacitance-voltage characteristics are used to determine the junction built-in potential at different frequencies. A capacitance relaxation is found due to charge trapping at interface states. Interface states, which deeply affect transport, are discussed in connection to charge-transfer processes related to the polarity mismatch at the interface., MEC, NSF DMR, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

We report on the magnetic coupling of La0.7Sr0.3MnO3 layers through SrTiO3 spacers in La0.7Sr0.3MnO3/SrTiO3 epitaxial heterostructures. Combined aberration-corrected microscopy and electron-energy-loss spectroscopy evidence charge transfer to the empty conduction band of the titanate. Ti d electrons interact via superexchange with Mn, giving rise to a Ti magnetic moment as demonstrated by x-ray magnetic circular dichroism. This induced magnetic moment in the SrTiO3 controls the bulk magnetic and transport properties of the superlattices when the titanate layer thickness is below 1 nm., MICINN, CAM, U.S. Department of Energy, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License The authors acknowledge receiving funding from the project To2Dox of FlagERA ERANET Cofund implemented within the European Union's Horizon Europe Program. Work (J.S., C.L., F.M., M.G.-H.) supported by Spanish AEI through grants, PID2020-118078RB-I00 and by Regional Government of Madrid CAM through SINERGICO project Y2020/NMT-6661 CAIRO-CM. G.S.-S. acknowledges financial support from Spanish MCI Grant Nos. RTI2018-099054-J-I00 (MCI/AEI/FEDER, UE) and IJC2018-038164-I. M.C.M. acknowledges the financial support provided by PID2021-122980OB-C55. J.I.B. acknowledges the financial support provided by PID2021-122980OB-C51 and computational support provided by the Red Espanola de Supercomputacion under the projects FI-2018-1-0038 and FI-2019-3-0034., Strong spin-orbit coupling in SrIrO_3 mixes the orbital character of iridium d-bands, resulting in correlated narrow bands and a metal-insulator transition. Here, the electric field generated by ionic liquid gating is used to manipulate the band structure, triggering a reversible control of the metal-insulator transition. SrIrO_3 is a correlated semimetal with narrow t_2g d-bands of strong mixed orbital character resulting from the interplay of the spin-orbit interaction due to heavy iridium atoms and the band folding induced by the lattice structure. In ultrathin layers, inversion symmetry breaking, occurring naturally due to the presence of the substrate, opens new orbital hopping channels, which in presence of spin-orbit interaction causes deep modifications in the electronic structure. Here, we show that in SrIrO_3 ultrathin films the effect of inversion symmetry breaking on the band structure can be externally manipulated in a field effect experiment. We further prove that the electric field toggles the system reversibly between a metallic and an insulating state with canted antiferromagnetism and an emergent anomalous Hall effect. This is achieved through the spin-orbit driven coupling of the electric field generated in an ionic liquid gate to the electronic structure, where the electric field controls the band structure rather than the usual band filling, thereby enabling electrical control of the effective role of electron correlations. The externally tunable antiferromagnetic insulator, rooted in the strong spin-orbit interaction of iridium, may inspire interesting applications in spintronics., Unión Europea. H2020, Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Red Española de Supercomputación (RES), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Institute of Physics. The authors thank Professor A. Várez for sample preparation. One of the authors (A.R.) thanks another (E.R.) for his hospitality during the stay in Bayreuth., We report on the temperature dependence of the ionic conductivity at low temperatures in the crystalline lithium ionic conductor Li_(0.18)La_(0.61)TiO_(3). Time domain measurements of the electric modulus have been performed to investigate ion dynamics in the frequency range 1025 – 102 Hz and for conductivity values in the range 10214 – 1028 S/cm. Ionic conductivity shows an Arrhenius temperature dependence below 300 K and down to 120 K, in contrast to the non-Arrhenius behavior found at higher temperatures, demonstrating that the temperature dependence of ionic conductivity in Li_(0.18)La_(0.61)TiO_(3) cannot be described by a Vogel–Fulcher–Tamman law., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

We acknowledge financial support by Spanish MICINN through grants MAT2011-27470-C01 and Consolider Ingenio 2010 - CSD2009-00013 (Imagine), by CAM through grant S2009/MAT-1756 (Phama) and by the ERC starting Investigator Award, grant #239739 STEMOX. RS wishes to acknowledge the MICINN (Spain) for granting a Ramon y Cajal fellowship. MAF is Research Fellow of CONICET (Argentine). Financial support of CONICET is gratefully acknowledged. OJD acknowledges a postdoctoral fellowship from JCCM. JS acknowledges a Juan de la Cierva fellowship from MICINN (Spain). The authors thank Dr. Hugo Schlich from Mateck GmbH for providing information about the process of bicrystals production, Masashi Watanabe for the Digital Micrograph PCA plug-in and J. Luck for help with specimen preparation, and A. de Andrés for helpful discussion and assistance on experimental matters. Electron microscopy observations at ORNL (SJP, MV) were sponsored by the Materials Sciences and Engineering Division of the U.S. Department of Energy (DOE) and and through the Center for Nanophase Materials Sciences (CNMS), which is sponsored by the Scientific User Facilities Division, DOE-BES. ESM measurements (SVK, SJ, AK) were performed at the Center for Nanophase Materials Sciences and supported by the Division of Scientific User Facilities of the U.S. Department of Energy (DOE)., The blocking of ion transport at interfaces strongly limits the performance of electrochemical nanodevices for energy applications. The barrier is believed to arise from space-charge regions generated by mobile ions by analogy to semiconductor junctions. Here we show that something different is at play by studying ion transport in a bicrystal of yttria (9% mol) stabilized zirconia (YSZ), an emblematic oxide ion conductor. Aberration-corrected scanning transmission electron microscopy (STEM) provides structure and composition at atomic resolution, with the sensitivity to directly reveal the oxygen ion profile. We find that Y segregates to the grain boundary at Zr sites, together with a depletion of oxygen that is confined to a small length scale of around 0.5nm. Contrary to the main thesis of the space-charge model, there exists no evidence of a long-range O vacancy depletion layer. Combining ion transport measurements across a single grain boundary by nanoscale electrochemical strain microscopy (ESM), broadband dielectric spectroscopy measurements, and density functional calculations, we show that grain-boundary-induced electronic states act as acceptors, resulting in a negatively charged core. Besides the possible effect of the modified chemical bonding, this negative charge gives rise to an additional barrier for ion transport at the grain boundary., Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Consolider Ingenio 2010, ERC starting Investigator Award, CONICET, JCCM, Materials Sciences and Engineering Division of the U.S. Department of Energy (DOE), Center for Nanophase Materials Sciences (CNMS), Scientific User Facilities Division, DOE-BES, Division of Scientific User Facilities of the U.S. Department of Energy (DOE), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2016 Elsevier B.V. This research has been financed by the “Ministerio de Ciencia e Innovación” (MICINN, Spain) and by the “Fundación Neurociencias y Envejecimiento” (Spain) through grants MAT2010-18432 and 4153592, 4143942 respectively as well as by the MAT2013-40722-R project., Li_(1+x)M_(x)Ti_(2−x)(PO_(4))_(3) powders with x = 0 and 0.3 and M = Al, Cr and Fe have been sintered by conventional sintering (CS) and Spark Plasma Sintering (SPS), and the electrical properties have been compared. The use of SPS allows preparing samples with higher density at lower temperature and shorter time than the CS, avoiding segregation of secondary phases and with reduced crystallite size. The introduction of aluminum, chromium and iron in the LiTi_(2)(PO_(4))_(3) (LTP) clearly enhances ionic conductivity even if the samples have similar densities. Despite the different level of density reached with CS and SPS, the activation energies of dc and grain boundary contributions are very similar and the differences in ionic conductivity are determined by pre-exponential factors. The samples produced by SPS showed a well-defined grain boundary meaning a more homogenous electrical contact., Ministerio de Ciencia e Innovación (MICINN, Spain), Fundación Neurociencias y Envejecimiento (Spain), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2002 The American Physical Society., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2014 AIP Publishing LLC. We acknowledge financial support by Spanish MICINN through Grants MAT2011-27470-C02 and Consolider Ingenio 2010-CSD2009-00013 (Imagine), by CAM through grant S2009/MAT-1756 (Phama). We thank Patrizia De Marco, Francesco Perrozzi, and Luca Ottaviano for their help and guidance in preparing the graphene samples. We thank Susana Álvarez and Alicia de Andrés for help with preliminary Raman spectroscopy experiments, We report on the fabrication and magnetotransport characterization of hybrid graphene-based nanodevices with epitaxial nanopatterned La_(0.7)Sr_(0.3)MnO_(3) manganite electrodes grown on SrTiO_(3)(100). The few-layer graphene was deposited onto the predefined manganite nanowires by using a mechanical transfer technique. These nanodevices exhibit resistive switching and hysteretic transport as measured by current-voltage curves. The resistance can be reversibly switched between high and low states, yielding a consistent non-volatile memory response. The effect is discussed in terms of changes in the concentration of oxygen vacancies at the space charge region of the Schottky barriers building at the contacts., Minsiterio de Ciencia e Innovación (MICINN), Consolider Ingenio 2010, Comunidad de Madrid, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2010 Macmillan Publishers Limited. We thank Andrew Millis and Giniyat Khaliullin for stimulating discussions. J.G.-B. thanks the Spanish Ministry of Science and Innovation (MICINN) for financial support through the Specialization in International Organizations fellowship. This work was supported by Spanish MICINN Grant MAT 2008 06517, Consolider Ingenio CSD2009-00013 (IMAGINE), CAM S2009-MAT 1756 (PHAMA). Work at ORNL was supported by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy. Some XMCD experiments were conducted with the approval of JASRI (proposal no. 2007B1516) and supported by UK EPSRC Grants EP/F062729 and EP/G056463/1., In systems with strong electron-lattice coupling, such as manganites, orbital degeneracy is lifted, causing a null expectation value of the orbital magnetic moment. Magnetic structure is thus determined by spin–spin superexchange. In titanates, however, with much smaller Jahn–Teller distortions, orbital degeneracy might allow non-zero values of the orbital magnetic moment, and novel forms of ferromagnetic superexchange interaction unique to t_2g electron systems have been theoretically predicted, although their experimental observation has remained elusive. In this paper, we report a new kind of Ti^3+ ferromagnetism at LaMnO_3/SrTiO_3 epitaxial interfaces. It results from charge transfer to the empty conduction band of the titanate and has spin and orbital contributions evidencing the role of orbital degeneracy. The possibility of tuning magnetic alignment (ferromagnetic or antiferromagnetic) of Ti and Mn moments by structural parameters is demonstrated. This result will provide important clues for understanding the effects of orbital degeneracy in superexchange coupling., Ministerio de Ciencia e Innovación (MICINN), España, Specialization in International Organizations, Consolider Ingenio, U.S. Department of Energy, EE.UU., Engineering and Physical Sciences Research Council (EPSRC), Reino Unido, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2015 Macmillan Publishers Limited. We acknowledge financial support from the European Research Council (ERC Advanced Grant FEMMES, No. 267579) and the Labex NanoSaclay project FIRET. The ALICE project is supported by the BMBF Contract No. 05K10PC2. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 226716. Work at UCM was supported by grants MAT2011-27470-C02 and Consolider Ingenio 2010—CSD2009- 00013 (Imagine), by CAM through grant S2009/MAT-1756 (Phama) and by the ERC starting Investigator Award, grant #239739 STEMOX. Microscopy at ORNL (M.V.) was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. We thank N.M. Nemes and M. Garcı´a- Herna´ndez for collaboration and assistance with the preliminary magnetic characterization of the LSMO/LFO structures and V. Garcia for his constructive comments. Author contributions: F.Y.B., J.S., A.B. and M.B. designed and conceived the experiment. F.Y.B. and A.R.-C. were involved in sample growth and characterization. F.Y.B. and C.V were involved in lithography process and transport measurements. S.V. conceived the synchrotron experiments. F.Y.B., S.V., R.A., J.T., A.A.U¨ . and A.R.-C. were involved in synchrotron measurements and data analysis. M.V. and S.J.P. performed electron microscopy. M.N.G. and M.B performed tunnelling magneto-resistance simulations. F.Y.B., M.N.G., C.V., Z.S., C.L., J.E.V., J.S., A.B. and M.B analyzed the data and discussed the manuscript. F.Y.B. and M.B. wrote the article with inputs from all co-authors. Competing financial interests: The authors declare no competing financial interests., At interfaces between complex oxides, electronic, orbital and magnetic reconstructions may produce states of matter absent from the materials involved, offering novel possibilities for electronic and spintronic devices. Here we show that magnetic reconstruction has a strong influence on the interfacial spin selectivity, a key parameter controlling spin transport in magnetic tunnel junctions. In epitaxial heterostructures combining layers of antiferromagnetic LaFeO_3 (LFO) and ferromagnetic La_0.7Sr_0.3MnO_3 (LSMO), we find that a net magnetic moment is induced in the first few unit planes of LFO near the interface with LSMO. Using X-ray photoemission electron microscopy, we show that the ferromagnetic domain structure of the manganite electrodes is imprinted into the antiferromagnetic tunnel barrier, endowing it with spin selectivity. Finally, we find that the spin arrangement resulting from coexisting ferromagnetic and antiferromagnetic interactions strongly influences the tunnel magnetoresistance of LSMO/LFO/LSMO junctions through competing spin-polarization and spin-filtering effects., Unión Europea. FP7, Comunidad Autónoma de Madrid, Ministerio de Economía y Competitividad (MINECO), Labex NanoSaclay project FIRET, ALICE Project (BMBF), Bundesministerium für Bildung und Forschung (BMBF), Alemania, European Research Council, Programa Consolider-Ingenio (Imagine), MINECO, España, ERC starting Investigator Award STEMOX, US Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division, PHOTONIC ADVANCED MATERIALS: PHAMA 2.0-CM PROGRAMME, Consejo Superior de Investigaciones Científicas (CSIC), España, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© Sociedad Española de Cerámica y Vidrio. National Meeting on Electroceramics (9. 2009. Madrid). Este trabajo ha sido realizado gracias al proyecto PR34/07-15895 BSCH-UCM., Haciendo uso de la química sol-gel, se han preparado ortofosfatos de composición LiTi_(2)(PO_(4))_(3) y Li_(1.05)(Cr/Fe)_(0.05)Ti_(1.95)(PO_(4))_(3) a temperaturas moderadas mediante el método Pechini. Estas fases han sido caracterizadas estructural y microestructuralmente por difracción de rayos X de polvo y microscopía electrónica de barrido (SEM), encontrándose que todas cristalizan en una estructura tipo NASICON, con parámetros de red muy similares. El dopaje con Fe y Cr permite aumentar la densidad de las muestras en la sinterización, mejorando de forma apreciable su conductividad iónica. Se ha observado un incremento de hasta cuatro órdenes de magnitud en la conductividad a temperatura ambiente obteniéndose una energía de activación de 0.29 eV para el material dopado con Cr., Compounds of formula Li_(1+x)M^(III)_(x)Ti_(2-x)(PO_(4))_(3) with M^(III)=Cr,Fe and x=0 and 0.05 have been prepared at soft temperatures using the Pechini synthesis method, based on sol-gel chemistry. The structural and microstructural characterization by X-ray diffraction and Scanning Electron Microscopy (SEM), shows that all of them crystallize in a NASICON-type structure with similar lattice parameters. Doping with Fe and Cr, causes an increase of the density of the samples after sinterization what clearly improves the ionic conductivity of the original material, LiTi_(2)(PO_(4))_(3) until values of 9x10^(-4) S cm^(-1) at room temperature in the chromium-doped material., BSCH-UCM, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2001 American Institute of Physics., We report on complex admittance measurements on ZrO_(2):Y_(2)O_(3) (YSZ) thin films in the parallel plate geometry. Highly textured YSZ thin films, grown by rf sputtering, allow measuring complex admittance free of the effect of charge blocking at grain boundaries. We have examined low-temperature (close to room temperature) regime dominated by association of oxygen vacancies. Complex admittance analyzed in terms of the modulus formalism supplies information on correlation effects in ion motion and allows obtaining an association energy for the oxygen vacancies of 0.45 eV, in agreement with previous theoretical calculations., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2010 The American Physical Society. We acknowledge financial support by Junta de Comunidades de Castilla-La Mancha through Project No. PAI-05- 013, by CAM under Grant No. S2009/MAT-1756 Phama, by Spanish MICINN through Grants No. MAT2008-06517- C02, No. MAT2008-06542-C04, and No. FIS2009-12964- C05-04, and Consolider Ingenio 2010 under Grant No. CSD2009-00013 Imagine. We thank J. Garcia-Barriocanal for helpful discussions. We are indebted to the staff of SpLine for their help during the experimental work at ESRF., We report on the effect of grain size on the ionic conductivity of yttria-stabilized zirconia samples synthesized by ball milling. Complex impedance measurements, as a function of temperature and frequency are performed on 10 mol % yttria-stabilized zirconia nanocrystalline samples with grain sizes ranging from 900 to 17 nm. Bulk ionic conductivity decreases dramatically for grain sizes below 100 nm, although its activation energy is essentially independent of grain size. The results are interpreted in terms of a space-charge layer resulting from segregation of mobile oxygen vacancies to the grain-boundary core. The thickness of this space-charge layer formed at the grain boundaries is on the order of 1 nm for large micron-sized grains but extends up to 7 nm when decreasing the grain size down to 17 nm. This gives rise to oxygen vacancies depletion over a large volume fraction of the grain and consequently to a significant decrease in oxide-ion conductivity., Junta de Comunidades de Castilla-La Mancha, CAM, Spanish MICINN, Consolider Ingenio 2010, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

The local order around Zr and Y atoms of nanocrystalline yttria-stabilized zirconia (YSZ) powders with different grain sizes has been investigated by x-ray absorption spectroscopies. The samples were prepared by means of mechanical alloying with or without subsequent sintering treatment and also by milling commercial YSZ. Our study is motivated by the interest in the electrical properties of grain boundaries and the controversy about the level of disorder in the intergrain regions in nanocrystalline YSZ. The x-ray absorption near edge structure (XANES) analysis indicates that the local order of all the sintered samples is independent of the grain size. This is confirmed by the analysis of the extended x-ray absorption fine structure, which points out also that, in contrast to that found in sintered samples, the local order around the cation in the samples milled without further sintering treatment extends only to the first coordination shell. Finally, the results of ab initio Zr K-edge XANES calculations lead us to conclude that the observed changes of the shape of the white line are not related to a phase transformation but reflects the short-range order present in the as-milled samples., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2023 American Physical Society The synthesis of the heterostructures and measurement of transport, magnetic, and optical properties were supported by the U.S. Department of Energy's Office of Basic Energy Science, under Grant DE-FG02-87ER45332, the synthesis of LSMO by the Spanish MCI through Grants No. MAT 2017-87134-C02 and No. PCI 2020-112093, and theory by the French ANR "MoMA" project ANR-19-CE30-0020, Chilean FONDECYT 1211902, and Basal AFB220001., The strongly correlated material La_0.7Sr_0.3MnO_3 (LSMO) exhibits metal-to-insulator and magnetic tran-sition near room temperature. Although the physical properties of LSMO can be manipulated by strain, chemical doping, temperature, or magnetic field, they often require large external stimuli. To include addi-tional flexibility and tunability, we developed a hybrid optoelectronic heterostructure that uses photocarrier injection from cadmium sulfide (CdS) to an LSMO layer to change its electrical conductivity. LSMO exhibits no significant optical response; however, the CdS/LSMO heterostructures show an enhanced conductivity, with a resistance drop of about 37%, at the transition temperature under light stimuli. This enhanced conductivity in response to light is comparable to the effect of a 9 T magnetic field in pure LSMO. Surprisingly, the optical and magnetic responses of CdS/LSMO heterostructures are decoupled and exhibit different effects when both stimuli are applied. This unexpected behavior shows that het-erostructuring strongly correlated oxides may require a new understanding of the coupling of physical properties across the transitions and provide the means to implement new functionalities., U.S. Department of Energy's Office of Basic Energy Science, Ministerio de Ciencia e Innovación (MICINN), Agence nationale de la recherche (ANR), Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2014 AIP Publishing LLC. Financial support by the Spanish Government [Project Nos. MAT2011-29269-CO3 and NANOSELECT CSD2007- 00041] and Generalitat de Catalunya (No. 2009 SGR 00376) is acknowledged., We show that yttria-stabilized zirconia (YSZ) films deposited on structurally dissimilar SrTiO_(3)(110) substrates exhibit two-dimensional layer-by-layer growth. We observed that, up to a thickness of about 15 nm, the square (001) basal plane of the cubic YSZ grows epitaxially on the rectangular (110) crystallographic plane of SrTiO3 substrates, with [110]YSZ(001)//[001]SrTiO_(3)(110) epitaxial relationship. Thus, the heterointerface presents symmetry discontinuity between the YSZ(001) film and the lower surface symmetry SrTiO_(3)(110) substrate. Beyond this specific case, we envisage similar approaches to develop other innovative oxide interfaces showing similar crystal symmetry discontinuities., Ministerio de Economía y Competitividad (MINECO), Generalitat de Catalunya, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2004 The American Physical Society. C.L. and A.R. thank J. Santamaría for fruitful discussions. Financial support from CICYT Grant No. MAT2001-3713- C04 is acknowledged. The work performed at NRL was supported by ONR., For ionic conductivity relaxation in ionically conducting materials we predict in the framework of the coupling model that the magnitude of the ubiquitous near constant loss correlates with the activation energy E_(a) for independent ion hopping. Using experimental data of a variety of ionic conductors, this correlation has been borne out. The model also explains the observed correlation between the magnitude of the near constant loss and the value of the dc conductivity at room temperature, as well as the temperature dependence for the near constant loss., CICYT, ONR, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

The synapsis of DNA ends is a critical step for the repair of double-strand breaks by non-homologous end joining (NHEJ). This is performed by a multicomponent protein complex assembled around Ku70-Ku80 heterodimers and regulated by accessory factors, including long non-coding RNAs, through poorly understood mechanisms. Here, we use magnetic tweezers to investigate the contributions of core NHEJ proteins and APLF and lncRNA NIHCOLE to DNA synapsis. APLF stabilizes DNA end bridging and, together with Ku70-Ku80, establishes a minimal complex that supports DNA synapsis for several minutes under piconewton forces. We find the C-terminal acidic region of APLF to be critical for bridging. NIHCOLE increases the dwell time of the synapses by Ku70-Ku80 and APLF. This effect is further enhanced by a small and structured RNA domain within NIHCOLE. We propose a model where Ku70-Ku80 can simultaneously bind DNA, APLF, and structured RNAs to promote the stable joining of DNA ends.

Generation, manipulation, and sensing of magnetic domain walls are cornerstones in the design of efficient spintronic devices. Half-metals are amenable for this purpose as large low field magnetoresistance signals can be expected from spin accumulation at spin textures. Among half metals, La1−xSrxMnO3 (LSMO) manganites are considered as promising candidates for their robust half-metallic ground state, Curie temperature above room temperature (Tc = 360 K, for x = 1/3), and chemical stability. Yet domain wall magnetoresistance is poorly understood, with large discrepancies in the reported values and conflicting interpretation of experimental data due to the entanglement of various source of magnetoresistance, namely, spin accumulation, anisotropic magnetoresistance, and colossal magnetoresistance. In this work, the domain wall magnetoresistance is measured in LSMO cross-shape nanowires with single-domain walls nucleated across the current path. Magnetoresistance values above 10% are found to be originating at the spin accumulation caused by the mistracking effect of the spin texture of the domain wall by the conduction electrons. Fundamentally, this result shows the importance on non-adiabatic processes at spin textures despite the strong Hund coupling to the localized t2g electrons of the manganite. These large magnetoresistance values are high enough for encoding and reading magnetic bits in future oxide spintronic sensors. © 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.