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

©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

[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.

©2022 American Chemical Society The authors acknowledge Prof. J. M. Alameda and Prof. G. Armelles for fruitful discussion. This work was supported by Comunidad de Madrid and Universidad Complutense de Madrid under the project 2018-T1/IND-10360 granted by “Atracción de Talento” program, the European Union under the H2020 research and innovation Marie Sklodowska-Curie Grant Agreement MAGNAMED 734801 (H2020-MSCA-RISE-2016), the Spanish MINECO grants FIS2016-76058 (AEI/FEDER, UE), PID2019- 104604RB/AEI/ 10.13039/501100011033, PID2021-122980OB-C52 and Basque Government grant IT1491-22. The magnetic measurements and interpretation were funded by the Department of Energy’s Office of Basic Energy Science, under grant # DE-FG02-87ER45332. IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MICINN, Grant CEX2020-001039-S). The design of the experiments and the multiple versions of the manuscript were discussed and written with extensive contributions from all the authors., Controlling the magnetic ground states at the nanoscale is a longstanding basic research problem and an important issue in magnetic storage technologies. Here, we designed a nanostructured material that exhibits very unusual hysteresis loops due to a transition between vortex and double pole states. Arrays of 700 nm diamond-shaped nanodots consisting of Py(30 nm)/Ru(tRu)/Py(30 nm) (Py, permalloy (Ni_(80)Fe_(20)) trilayers were fabricated by interference lithography and e-beam evaporation. We show that varying the Ru interlayer spacer thickness (t_(Ru)) governs the interaction between the Py layers. We found this interaction mainly mediated by two mechanisms: magnetostatic interaction that favors antiparallel (antiferromagnetic, AFM) alignment of the Py layers and exchange interaction that oscillates between ferromagnetic (FM) and AFM couplings. For a certain range of Ru thicknesses, FM coupling dominates and forms magnetic vortices in the upper and lower Py layers. For Ru thicknesses at which AFM coupling dominates, the magnetic state in remanence is a double pole structure. Our results showed that the interlayer exchange coupling interaction remains finite even at 4 nm Ru thickness. The magnetic states in remanence, observed by magnetic force microscopy (MFM), are in good agreement with corresponding hysteresis loops obtained by the magneto-optic Kerr effect (MOKE) and micromagnetic simulations., Unión Europea. H2020, Ministerio de Economía y Competitividad (MINECO)/AEI/FEDER, Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid / Universidad Complutense (UCM), País Vasco, Centros de Excelencia Severo Ochoa (MICINN), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

CRUE-CSIC (Acuerdos Transformativos 2021) ©2021 The Author(s). Published by Elsevier This work has been supported by the Ministerio de Ciencia e Innovación (MCINN, Spain) through the projects PIE: 2021-60-E-030, PIE: 2010-6-OE-013, PID2019-104717RB-I00 (2020–2022), MAT2017- 86540-C4-1-R, RTI2018-095856-B-C21 (2019–2021), RTI2018- 097895-B-C43 and RTI2018-095303-A-C52. The authors are grateful to The ESRF (France), MCINN and Consejo Superior de Investigations Científicas (CSIC, Spain) for the provision of synchrotron radiation facilities and to the BM25-SpLine Staff for their valuable help. A.S. and A.M.-N acknowledge financial support from Comunidad de Madrid (Spain) for an “Atracción de Talento Investigador” Contract 2017-t2/IND5395 and 2018-T1/IND-10360, respectively, Epsilon iron oxide (epsilon-Fe_2O_3) coatings on Si(100) substrates are obtained by an easy one-pot sol-gel recipe assisted by glycerol in an acid medium. Glycerol, given its small dimensions, enables the formation of epsilon-Fe_2O_3 nanoparticles with a size of a few nanometers and the highest purity is reached in coatings after a densification treatment at 960 degrees C. The structural and compositional evolution up to 1200 degrees C is studied by confocal Raman microscopy and X-ray absorption spectroscopy techniques, correlating the existing magnetic properties. We report a novel characterization method, which allows monitoring the evolution of the precursor micelles as well as the intermediate and final phases formed. Furthermore, the inherent industrial technology transfer of the sol-gel process is also demonstrated with the epsilon-Fe_2O_3 polymorph, impelling its application in the coatings form., Ministerio de Ciencia e Innovacion (MICINN), Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

CRUE-CSIC (Acuerdos Transformativos 2021) © 2021 The Author(s). Published by Elsevier B.V. We thank 'CAI Difraccion de rayosX' of UCM for Xray diffractometry measurements, and ICTS Centro Nacional de Microscopia of UCM for SEM characterization. We also acknowledge beamtime at BM-25A at the European Synchrotron (ESRF) , and at BL22-CLAESS at ALBA synchrotron. This work has been financially supported through the projects MAT2015-66888-C3-3-R (MINECO/FEDER) and RTI2018-097895-B-C43 of the Spanish Ministry of Economy and Competitiveness. A. P. would like to acknowledge the postdoctoral fellowship granted by Consejea de Educacion, Juventud y Deporte of Comunidad de Madrid and the European Social Fund (grant PEJD-2016/IND-2233 of the YEI program), In this work we present an exhaustive investigation about the possibility of using the electrodeposition technique to grow Ga-Fe-O thin films. The morphological and structural characterization has been performed by means of scanning electron microscopy, X-ray diffractometry and X-ray absorption near edge structure measurements. These results have been complemented with chronoamperometric measurements recorded during growth. We have explored different electrolytes, growth potentials, and pH being observed that it is possible to tune the Fe/ Ga ratio by means of the potential whereas the surface morphology is closely related to the Na_3-citrate content in the electrolyte. The surface roughness is reduced as the Fe content in the layer is increased upon the raise of citrate in the electrolyte composition. X-ray diffractometry indicates that Ga can become partially oxidized, whereas Fe seems to keep its metallic state in its vast majority since we have not obtained clear evidences of oxidation. Thus, this investigation highlights the inherent difficulties to synthetize Ga-Fe-O compounds by means of the electrodeposition technique., Ministerio de Economía y Competitividad (MINECO)/FEDER, Ministerio de Innovación y Ciencia (MICINN)/FEDER, Comunidad de Madrid /FSE, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2021 Elsevier Science We gratefully acknowledge the Spanish CRG at the ESRF for providing beamtime under experiment HC-3343. MS thanks Prof. Monica Dapiaggi for useful discussions. GL thanks Prof. Fabio M. Canepa for illuminating discussions. F.R.-M. gratefully acknowledge the support of the AEI (Spanish Government) Project (No. MAT2017-86450-C4-1-R). F.R.-M. is indebted to MINECO for the "Ramon y Cajal" contract (Ref: RyC-2015-18626), which is co-financed by the European Social Fund., We present an extended X-ray absorption fine structure study at the Mo K-edge of A_2(Mo_(1-y)Mn_y)_2O_7 (A = Gd, Ho; y = 0.05 and 0.10) pyrochlores, as a function of temperature and composition, coupled to diffractometric and magnetic characterizations. Extending the study reported in our previous paper on the pristine A_2Mo_2O_7 compounds to these Mo/Mn partially substituted samples, where we hypothesize a competition between double-exchange and superexchange couplings, we aim to check which structure parameters are related to the nature of the nearest-neighbor magnetic interactions, looking for the presence and evolution of order and structure anomalies. Two Ho samples A_2(Mo_(1-y)Mn_y)_2O_7 (y = 0.05 and 0.10) keep the spin-glass nature of the parent compositions with a strong distortion of the MoO octahedron and of the Mo - Ho and Mo - Mo second shell. On the other hand, two Gd_2(Mo_(1-y)Mn_y)_2O_7 samples, ferromagnetic at low temperature in the undoped case, show the appearance on a local scale of a spin-glass transition mirrored by a quite high structure disorder and by a distortion coherent with a lattice frustration after Mn-doping. Therefore, the Gd and Ho Mn-doped samples display a similar frustrated behavior, differently from the corresponding undoped ones., Ministerio de Economía y Competitividad (MINECO), Centros de Excelencia Ramón y Cajal (MINECO), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©The Author(s) 2021 This work was supported by Spanish MICINN grants FIS2016-76058 (AEI/FEDER, UE), EU COST-CA16218. IMDEA Nanociencia acknowledges support from the 'Severo Ochoa' Programme for Centres of Excellence in R&D (MICINN, Grant SEV-2016-0686). MCO and AG acknowledges financial support from Spanish MICINN Grant ESP2017-86582-C4-1-R and IJCI-2017-33991; AMN acknowledges financial support from Spanish CAM Grant 2018-T1/IND-10360. MV acknowledges financial support from Spanish MICINN Grant PID2019-104604RB/AEI/10.13039/50110001103., 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 Neel 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 Neel 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., Unión Europea. H2020, Ministerio de Economía y Competitividad (MINECO) /FEDER, Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Centro de Excelencia Severo Ochoa (MICINN), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, unpub

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.

©2020 Elsevier The authors would like to acknowledge financial support from MAT2017-86450-C4-1-R, MAT2017-86450-C4-3-R, and RTI2018095303-A-C52. C.V.M acknowledges financial support from Juan de la Cierva Incorporacion grants IJCI-2017-31350. A.S. and A.M.N. acknowledge the financial support from the Comunidad de Madrid for an "Atraccion de Talento Investigador" contract No. 2017-t2/IND5395 and 2018-T1/IND-10360, respectively. We acknowledge The European Synchrotron (ESRF), MICIU, and CSIC for provision of synchrotron radiation facilities in using the BM25-SpLine beamline. We also thank the BM25-SpLine staff for the technical support beyond their duties. We acknowledge the service from the MiNa Laboratory at IMN, and funding from CM (project SpaceTec, S2013/ICE2822), MINECO (project CSIC13-4E-1794) and EU (FEDER, FSE)., 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_i )^0, (O_Zn)^0, (O_i)^(-/2-) and (O_Zn)^(0/-) 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., Ministerio de Economía y Competitividad (MINECO)/FEDER, Ministerio de Economía y Competitividad (MINECO), Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Juan de la Cierva, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2020 American Chemical Society We thank ALBA synchrotron for providing time and technical assistance at the BL22 beamline, and Instituto of Sistemas OptoelectrOnicos y Microtecnologia (ISOM) for using some of its facilities. This work has been financially supported through the projects MAT2015-66888-C3-3-R and MAT2015-66726-R (MINECO/FEDER) of the Spanish Ministry of Economy and Competitiveness, RTI2018-097895-B-C43 of the Spanish Ministry of Science, Innovation, and Universities, and Gobierno de Aragon (Grant E10 -17D) and Fondo Social Europeo. A.M.-N. is thankful for the contract from Universidad Complutense and Comunidad de Madrid "Atraccion de Talento" program 2018-T1/IND-10360, and A.B. thanks MINECO for the Ph.D. grant BES-2016-076482., 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., Ministerio de Economía y Competitividad (MINECO) / FEDER, Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Competitividad (MINECO), Gobierno de Aragón, Comunidad de Madrid / Universidad Complutense de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2020 The author(s). We want to thank Spanish MICINN Grants FIS2016-76058 AEI/FEDER, UE), EU COST-CA16218. IMDEA Nanociencia acknowledges support from the 'Severo Ochoa' Programme for Centres of Excellence in R&D (MICINN, Grant SEV-2016-0686). MCO and AG acknowledges financial support from Spanish MICINN Grant ESP2017-86582-C4-1-R and IJCI-2017-33991; AMN acknowledges financial support from Spanish CAM Grant 2018-T1/IND-10360., 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., Unión Europea. Horizonte 2020, Unión Europea. H2020/COST, Ministerio de Economía y Competitividad (MINECO)/AEI/FEDER, Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Centros de Excelencia Severo Ochoa (MICINN), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

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.

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.

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.

©2019 IOP Publishing We thank support from Spanish MINECO grants FIS201676058 (AEI/FEDER, UE), Spanish CM grant S2013/MIT2850. IMDEA Nanociencia acknowledges support from the 'Severo Ochoa' Programme for Centres of Excellence in R&D (MINECO, Grant SEV-2016-0686). DG acknowledges RYC-2012-09864, S2013/MIT-3007 and ESP2015-65597-C4-3-R for financial support and AG acknowledges financial support from Spanish MINECO Grant ESP2015-65597-C4-1-R., 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 Neel walls; (iii) the interaction between superconducting vortices and the asymmetric potentials provided by the Neel 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., Ministerio de Economía y Competitividad (MINECO)/AEI/FEDER, Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Centros de Excelencia Severo Ochoa (MINECO), Programa Ramón y Cajal, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2019 The Author(s) This journal is © The Royal Society of Chemistry 2019 Artículo firmado por más de diez autores. Dr Paloma Almodovar is acknowledged for her fruitful discussions about CRM and SEM characterization. The authors also acknowledge the Spanish Ministry of Industry, Economy and Competitiveness for financing the project MAT2015-65445-C2-1-R, MAT2017-86450-C4-1-R, MAT2015-67557-C2-1-P, by the Comunidad de Madrid S2013/MIT-2850 NANOFRONTMAG and H2020 AMPHIBIAN Project ID: 720853. The authors are also grateful to the BM25-SpLine staff for their valuable technical support beyond their duties and for the financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) and The Spanish National Research Council (CSIC) under Grant No. PIE 2010-6OE-013, The ESRF - The European Synchrotron, MICIU and CSIC are acknowledged for provision of synchrotron radiation facilities. A. S. acknowledges the financial support from the Comunidad de Madrid for an "Atraccion de Talento Investigador" contract (No. 2017-t2/IND5395)., 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 epsilon-Fe_2O_3 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 degrees C 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 epsilon-Fe_2O_3 nanoparticles in coatings and controlling their purity by an easy one-pot sol-gel method., Unión Europea. H2020, Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Consejo Superior de Investigaciones Científicas (CSIC), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2019 Wiley-V C H VERLAG GMBH We thank Agencia Estatal de Investigacion(AEI)/Fondo Europeo de Desarrollo Regional (FEDER/UE) for funding the project MAT2016-78632-C4-1-R. We acknowledge CSIC, ILL, and ESRF for financial support and facilitated access to the BM25-SpLine line at ESRF and D2B diffractometer at ILL. The authors also thank "Comunidad de Madrid" and the European Structural Funds for their financial support to the ALCCONES (S2013/MAE-2985) and MATERYENER3-CM (S2013/MIT-2753) projects., Materials with the formula Sr_2CoNb_1-xTi_xO_(6-delta) (x=1.00, 0.70; delta=number of oxygen vacancies) present a cubic perovskite-like structure. They are easily and reversibly reduced in N_2 or Ar and re-oxidized in air upon heating. Oxidation by water (wet N_2), involving splitting of water at a temperature as low as 700 ºC, produces hydrogen. Both compounds displayed outstanding H_2 production in the first thermochemical cycle, the Sr_2CoNb_(0.30)Ti_(0.70)O_(6-delta) material retaining its outstanding performance upon cycling, whereas the hydrogen yield of the x=1 oxide showed a continuous decay. The retention of the materials' ability to promote water splitting correlated with their structural, chemical, and redox reversibility upon cycling. On reduction/oxidation, Co ions reversibly changed their oxidation state to compensate the release/recovery of oxygen in both compounds. However, in Sr_2CoTiO_(6-delta), two phases with different oxygen contents segregated, whereas in Sr_2CoNb_(0.30)Ti_(0.70)O_(6-delta) this effect was not evident. Therefore, this latter material displayed a hydrogen production as high as 410 mu molH_2/g_(perovskite) after eight thermochemical cycles at 700 ºC, which is among the highest ever reported, making this perovskite a promising candidate for thermosolar water splitting in real devices., Ministerio de Economía y Competitividad (MINECO) / FEDER, Comunidad de Madrid/FEDER, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2019 The Author(s). Published by IOP Publishing Ltd We want to thank I K Schuller and V Bekeris for illuminating discussions, M Buchacek for useful suggestions and J Romero (CAI Tecnicas Fisicas, UCM) for his help with the SQUID measurements. The work has been supported by Spanish MICINN grants FIS2016-76058 (AEI/FEDER, UE), EU COST- CA16218. IMDEA Nanociencia acknowledges support from the 'Severo Ochoa' Programme for Centres of Excellence in R&D (MICINN, Grant SEV-2016-0686). AG acknowledges financial support from Spanish MICINN Grant ESP2017-86582-C4-1-R and IJCI-2017-33991; AMN acknowledges financial support from Spanish CAM Grant 2018-T1/IND-10360. JdV thanks Fundacion Ramon Areces for a postdoctoral fellowship., A controlled local enhancement of superconductivity yields unexpected modifications in the vortex dynamics. This local enhancement has been achieved by designing an array of superconducting Nb nanostructures embedded in a V superconducting film. The most remarkable findings are: (i) vanishing of the main commensurability effect between the vortex lattice and the array unit cell, (ii) hysteretic behavior in the vortex dynamics, (iii) broadening of the vortex liquid phase and (iv) strong softening of the vortex lattice. These effects can be controlled and they can be quenched by reducing the Nb array superconducting performance applying an in-plane magnetic field. These results can be explained by taking into account the repulsive potential landscape created by the superconducting Nb nanostructures on which vortices move., Unión Europea. H2020, Ministerio de Ciencia e Innovación (MICINN)/FEDER, Comunidad de Madrid, Centros de Excelencia Severo Ochoa (MICINN), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2019 American Chemical Society This work has been financially supported through project MAT2015-66888-C3-3-R (MINECO/FEDER) and RTI2018-097895-B-C43 of the Spanish Ministry of Economy and Competitiveness and through PR26/16-3B-2 of Santander and Universidad Complutense de Madrid. We thank "CAI Difraccion de rayos-X" of UCM for the X-ray diffractometry measurements and the "Instituto de Sistemas Optoelectronicos y Microtecnologia" (ISOM) for using its facilities. We also want to thank BM25-Spline, the Spanish CRG at ESRF for providing beamtime., We have investigated the influence of the growth power on the structural properties of Fe_100_(-x)Ga_x (x ca. 29) films sputtered in the ballistic regime in the oblique incidence. By means of different structural characterizations, mainly X-ray diffraction and X-ray absorption spectroscopy, we have reached a deeper understanding about the influence of the local and medium range order on the magnetic behavior of Ga-rich FeGa thin films. On the one hand, the increase of the growth power reduces the crystallite size (medium order) that promotes the decrease of the coercive field of the layers. On the other hand, the growth power also determines the local order as it controls the formation of the A2, B2, and D0_3 structural phases. The increase of the uniaxial in-plane magnetic anisotropy with growth power has been correlated with the enhancement of both Ga pairs and a tetragonal distortion. The results presented in this work give more evidence about the magnetic anisotropy sources in Ga-rich FeGa alloys, and therefore, it helps to understand how to achieve a better control of the magnetic properties in this family of alloys., Ministerio de Economía y Competitividad (MINECO)/FEDER, Ministerio de Economía y Competitividad (MINECO), Universidad Complutense de Madrid/Banco de Santander, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Resumen del trabajo presentado al American Physical Society (APS) March Meeting, celebrado del 4 al 8 de 2019 en Boston, Massachusetts (USA).

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.

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.

[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.

© 2018 Elsevier B.V. We thank ‘CAI Difracción de rayos-X’ of UCM for x-ray diffractometry measurements and ‘Instituto of Sistemas Optoelectrónicos y Microtecnología’ (ISOM) for using its facilities. We also want to thank BM25-Spline, the Spanish CRG at ESRF in Grenoble (France) for providing beamtime. This work has been financially supported through the project MAT2015-66888-C3-3-R of the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) and project PR26/16- 3B-2 of Santander and Universidad Complutense de Madrid., In this work we show the development of bulk in-plane magnetic anisotropy in high Ga-content (Ga = 28 at. %) Fe_(100-x)Ga_x thin films as the layer thickness increases. This result is in clear contrast with the generally reported decrease of this anisotropy with the film thickness. We propose the interrelation between the enhancement of the Ga-pair correlations and a collinear distortion of the bcc structure within the sample plane as the origin of the magnetic anisotropy. Our results have been obtained by employing a combination of long and local range structural probe techniques with bulk and surface magnetic characterization techniques. The key point shown in this work is that the in-plane structural anisotropy and hence, the magnetic anisotropy, are developed as the layer thickness increases. This fact strongly suggests that the surface to bulk free energy ratio plays a key role in the formation of ordered phases with a distorted bcc cell in Fe_(100-x)Ga_x films with x around 28 at. %. Our work also shows the arising of new phenomena in these high Ga content alloys due to the close correlation between structural and magnetic properties., Ministerio de Economía y Competitividad (MINECO)/FEDER, Universidad Complutense de Madrid/Banco de Santander, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

The perovskite series Sr2CoNb1@xTixO6@d (0,x,1) was investigated in the full compositional range to assess its potential as cathode material for solid oxide fuel cell (SOFC). The variation of transport properties and thus, the area specific resistances (ASR) are explained by a detailed investigation of the defect chemistry. Increasing the titanium content from x=0–1 produces both oxidation of Co 3+ to Co4+ (from 0 up to 40%) and oxygen vacancies (from 6.0 to 5.7 oxygen atom/formula unit), although each charge compensation mechanism predominates in different compositional ranges. Neutron diffraction reveals that samples with high Ti-contents lose a significant amount of oxygen upon heating above 600 K. Oxygen is partially recovered upon cooling as the oxygen release and uptake show noticeably different kinetics. The complex defect chemistry of these compounds, together with the compositional changes upon heating/cooling cycles and atmospheres, produce a complicated behavior of electrical conductivity. Cathodes containing Sr2CoTiO6@d display low ASR values, 0,13 Wcm2 at 973 K, comparable to those of the best compounds reported so far, being a very promising cathode material for SOFC., Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

© Amer Chemical Soc. This work was funded by Spanish MINECO under projects MAT2013-48009-C4-1-P, MAT2014- 52477-C5-2-P and MAT2015-64110-C2-1-P. We acknowledge the European Synchrotron Radiation Facility (ESRF), MINECO and CSIC for provision of synchrotron radiation facilites and the financial support for the beam line (PIE-2010-OE-013-200014). We would like to thank the BM25-SpLine staff for the technical support beyond their duties. We also acknowledge the use of the XRD facilities of the ISOM-UPM and thank A. Prados for her help during the XRD experiments. We also thank G. Pieplow for his help with the analysis using the FSD method. Belén Cortés acknowledges MINECO (FPI program) for her pre-doctoral fellowship., 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, Mossbauer, 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., Ministerio de Economía y Competitividad (MINECO), European Synchrotron Radiation Facility (ESRF), CSIC, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© Elsevier Science SA. This work has been financially supported through projects MAT2015-66888-C3-3-R and PIE-2010-OE-013-200014 of the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) and through the project PR26/16- 3B-2 of Santander and Universidad Complutense de Madrid. We thank “Instituto de Sistemas Optoelectrónicos y Microtecnología” (ISOM) for using its facilities. We also want to thank ESRF and BM25-Spline, the Spanish CRG at ESRF, for providing beamtime., We report on the evolution of the microstructure of Tb-Fe-Ga films deposited by co-sputtering from Tb_(33)Fe_(67) and Fe_(72)Ga_(28) targets. The sputtering power was fixed (90 W) in the Fe_(72)Ga_(28) whereas it was increased from 50 to 90 W in the Tb_(33)Fe_(67) target resulting on Tb_xFe_(73)Ga_(27-x) 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_(3) edges. The increase of Tb in the alloy promotes the phase segregation that produces a larger amount of the TbFe_2 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., Ministerio de Economía y Competitividad (MINECO), Universidad Complutense de Madrid/Banco de Santander, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

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.

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.

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.

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.

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.

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.

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.

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.

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.