Search

Your search keyword '"Alcalà, Jordi"' showing total 29 results
Start Over Author "Alcalà, Jordi"
29 results on '"Alcalà, Jordi"'

2. High harmonic spectroscopy of quantum phase transitions in a high-T$_c$ superconductor

Author

Alcalà, Jordi, Bhattacharya, Utso, Biegert, Jens, Ciappina, Marcelo, Elu, Ugaitz, Graß, Tobias, Grochowski, Piotr T., Lewenstein, Maciej, Palau, Anna, Sidiropoulos, Themistoklis P. H., Steinle, Tobias, and Tyulnev, Igor

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Materials Science, Physics - Optics
Abstract

We report on the new non--linear optical signatures of quantum phase transitions in the high-temperature superconductor YBCO, observed through high harmonic generation. While the linear optical response of the material is largely unchanged when cooling across the phase transitions, the nonlinear optical response sensitively imprints two critical points, one at the critical temperature of the cuprate with the exponential growth of the surface harmonic yield in the superconducting phase, and another critical point, which marks the transition from strange metal to pseudo gap phase. To reveal the underlying microscopic quantum dynamics, a novel strong-field quasi-Hubbard model was developed, which describes the measured optical response dependent on the formation of Cooper pairs. Further, the new theory provides insight into the carrier scattering dynamics and allows to differentiate between the superconducting, pseudo gap, and strange metal phases. The direct connection between non--linear optical response and microscopic dynamics provides a powerful new methodology to study quantum phase transitions in correlated materials. Further implications are light-wave control over intricate quantum phases, light-matter hybrids, and application for optical quantum computing.

Published
2022
Full Text
View/download PDF

3. Potential of Copper Oxide High-Temperature Superconductors for Tailoring Ferromagnetic Spin Textures

Author

Alcalà, Jordi, Roig, Mercè, Martín, Sergi, Barrera, Aleix, Fernández-Rodríguez, Alejandro, Pomar, Alberto, Balcells, Lluís, Coll, Mariona, Mestres, Narcís, Palau, Anna, Roca, Alejandro G., editor, Mele, Paolo, editor, Kijima-Aoki, Hanae, editor, Fantechi, Elvira, editor, Vejpravova, Jana K., editor, Kalbac, Martin, editor, Kaneko, Satoru, editor, and Endo, Tamio, editor

Published
2021
Full Text
View/download PDF

5. High harmonic spectroscopy of quantum phases in a high-Tc superconductor

Author

European Research Council, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, Fundació Privada Cellex, Alexander von Humboldt Foundation, Agencia Estatal de Investigación (España), Fundación Privada Mir-Puig, National Science Centre (Poland), Fundación la Caixa, European Cooperation in Science and Technology, Guangdong Province, Alcalà, Jordi, Bhattacharya, Utso, Ciappina, Marcelo, Elu, Ugaitz, Graß, Tobias, Grochowski, Piotr T., Lewenstein, Maciej, Palau, Anna, Sidiropoulos, Themistoklis P.H., Steinle, Tobias, Tyulnev, Igor, Biegert, Jens, European Research Council, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, Fundació Privada Cellex, Alexander von Humboldt Foundation, Agencia Estatal de Investigación (España), Fundación Privada Mir-Puig, National Science Centre (Poland), Fundación la Caixa, European Cooperation in Science and Technology, Guangdong Province, Alcalà, Jordi, Bhattacharya, Utso, Ciappina, Marcelo, Elu, Ugaitz, Graß, Tobias, Grochowski, Piotr T., Lewenstein, Maciej, Palau, Anna, Sidiropoulos, Themistoklis P.H., Steinle, Tobias, Tyulnev, Igor, and Biegert, Jens

Abstract

Ultrafast carrier dynamics are uniquely sensitive to the correlated interactions within quantum materials as well as their transition to different phases, like the emergence of superconductivity (SC) [1,2].

Published
2023

7. High-harmonic spectroscopy of quantum phase transitions in a high-Tc superconductor

Author

Alcalà, Jordi, primary, Bhattacharya, Utso, additional, Biegert, Jens, additional, Ciappina, Marcelo, additional, Elu, Ugaitz, additional, Graß, Tobias, additional, Grochowski, Piotr T., additional, Lewenstein, Maciej, additional, Palau, Anna, additional, Sidiropoulos, Themistoklis P. H., additional, Steinle, Tobias, additional, and Tyulnev, Igor, additional

Published
2022
Full Text
View/download PDF

9. Tunable Perpendicular Magnetoresistive Sensor Driven by Shape and Substrate Induced Magnetic Anisotropy

Author

Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Ciencia e Innovación (España), European Commission, Generalitat de Catalunya, European Cooperation in Science and Technology, Fonds de La Recherche Scientifique (Belgique), Barrera, Aleix, Fourneau, Emile, Martin Rio, Sergi, Batllori, Josep Maria, Alcalà, Jordi, Balcells, Lluis, Mestres, Narcís, Nguyen, Ngoc Duy, Sánchez, Álvaro, Silhanek, Alejandro V., Palau, Anna, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Ciencia e Innovación (España), European Commission, Generalitat de Catalunya, European Cooperation in Science and Technology, Fonds de La Recherche Scientifique (Belgique), Barrera, Aleix, Fourneau, Emile, Martin Rio, Sergi, Batllori, Josep Maria, Alcalà, Jordi, Balcells, Lluis, Mestres, Narcís, Nguyen, Ngoc Duy, Sánchez, Álvaro, Silhanek, Alejandro V., and Palau, Anna

Abstract

Control of magnetization reversal processes is a key issue for the implementation of magnetic materials in technological applications. The modulation of shape magnetic anisotropy in nanowire structures with a high aspect ratio is an efficient way to tune sharp in-plane magnetic switching. However, control of fast magnetization reversal processes induced by perpendicular magnetic fields is much more challenging. Here, tunable sharp magnetoresistance changes, triggered by out-of-plane magnetic fields, are demonstrated in thin permalloy strips grown on LaAlO3 single crystal substrates. Micromagnetic simulations are used to evaluate the resistance changes of the strips at different applied field values and directions and correlate them with the magnetic domain distribution. The experimentally observed sharp magnetic switching, tailored by the shape anisotropy of the strips, is properly accounted for by numerical simulations when considering a substrate-induced uniaxial magnetic anisotropy. These results are promising for the design of magnetic sensors and other advanced magnetoresistive devices working with perpendicular magnetic fields by using simple structures.

Published
2022

10. High-harmonic spectroscopy of quantum phase transitions in a high-Tc superconductor

Author

European Research Council, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, Fundació Privada Cellex, Alexander von Humboldt Foundation, Fundación Privada Mir-Puig, National Science Centre (Poland), La Caixa, Foundation for Polish Science, Polish Academy of Sciences, Ministerio de Economía y Competitividad (España), European Cooperation in Science and Technology, Guangdong Science and Technology Department, Alcalà, Jordi, Bhattacharya, Utso, Biegert, Jens, Ciappina, Marcelo, Elu, Ugaitz, Grass, Tobias, Grochowski, Piotr T., Lewenstein, Maciej, Palau, Anna, Sidiropoulos, Themistoklis P. H., Steinle, Tobias, Tyulnev, Igor, European Research Council, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, Fundació Privada Cellex, Alexander von Humboldt Foundation, Fundación Privada Mir-Puig, National Science Centre (Poland), La Caixa, Foundation for Polish Science, Polish Academy of Sciences, Ministerio de Economía y Competitividad (España), European Cooperation in Science and Technology, Guangdong Science and Technology Department, Alcalà, Jordi, Bhattacharya, Utso, Biegert, Jens, Ciappina, Marcelo, Elu, Ugaitz, Grass, Tobias, Grochowski, Piotr T., Lewenstein, Maciej, Palau, Anna, Sidiropoulos, Themistoklis P. H., Steinle, Tobias, and Tyulnev, Igor

Abstract

We report on the nonlinear optical signatures of quantum phase transitions in the high-temperature superconductor YBCO, observed through high harmonic generation. While the linear optical response of the material is largely unchanged when cooling across the phase transitions, the nonlinear optical response sensitively imprints two critical points, one at the critical temperature of the cuprate with the exponential growth of the surface harmonic yield in the superconducting phase and another critical point, which marks the transition from strange metal to pseudogap phase. To reveal the underlying microscopic quantum dynamics, a strong-field quasi-Hubbard model was developed, which describes the measured optical response dependent on the formation of Cooper pairs. Further, the theory provides insight into the carrier scattering dynamics and allows us to differentiate between the superconducting, pseudogap, and strange metal phases. The direct connection between nonlinear optical response and microscopic dynamics provides a powerful methodology to study quantum phase transitions in correlated materials. Further implications are light wave control over intricate quantum phases, light-matter hybrids, and application for optical quantum computing.

Published
2022

12. Chemical Synthesis of La0.75Sr0.25CrO3Thin Films for p-Type Transparent Conducting Electrodes

Author

Machado, Pamela, Guzmán, Roger, Morera, Ramon J., Alcalà, Jordi, Palau, Anna, Zhou, Wu, and Coll, Mariona

Abstract

The imperative need for highly performant and stable p-type transparent electrodes based on abundant metals is stimulating the research on perovskite oxide thin films. Moreover, exploring the preparation of these materials with the use of cost-efficient and scalable solution-based techniques is a promising approach to extract their full potential. Herein, we present the design of a chemical route, based on metal nitrate precursors, for the preparation of pure phase La0.75Sr0.25CrO3(LSCO) thin films to be used as a p-type transparent conductive electrode. Different solution chemistries have been evaluated to ultimately obtain dense, epitaxial, and almost relaxed LSCO films. Optical characterization of the optimized LSCO films reveals promising high transparency with ∼67% transmittance while room temperature resistivity values are 1.4 Ω·cm. It is suggested that the presence of structural defects, i.e., antiphase boundaries and misfit dislocations, affects the electrical behavior of LSCO films. Monochromated electron energy loss spectroscopy allowed changes in the electronic structure in LSCO films to be determined, revealing the creation of Cr4+and unoccupied states at the O 2pupon Sr-doping. This work offers a new venue to prepare and further investigate cost-effective functional perovskite oxides with potential to be used as p-type transparent conducting electrodes and be easily integrated in many oxide heterostructures.

Published
2023
Full Text
View/download PDF

14. Low-Fluorine Ba-Deficient Solutions for High-Performance Superconducting YBCO Films

Author

European Commission, Ministerio de Economía y Competitividad (España), European Cooperation in Science and Technology, Generalitat de Catalunya, Ternero, Pau, Alcalà, Jordi, Piperno, Laura, Pop, Cornelia, Ricart, Susagna, Mestres, Narcís, Obradors, Xavier, Puig Molina, Teresa, Sotgiu, Giovanni, Celentano, Giuseppe, Palau, Anna, European Commission, Ministerio de Economía y Competitividad (España), European Cooperation in Science and Technology, Generalitat de Catalunya, Ternero, Pau, Alcalà, Jordi, Piperno, Laura, Pop, Cornelia, Ricart, Susagna, Mestres, Narcís, Obradors, Xavier, Puig Molina, Teresa, Sotgiu, Giovanni, Celentano, Giuseppe, and Palau, Anna

Abstract

High-performing superconducting YBa2Cu3O7–x (YBCO) films are fabricated by a chemical solution deposition methodology through novel barium-deficient low-fluorine solutions. The precursor solutions, distinguished for being straightforward, inexpensive and eco-friendly, allow us to reduce the growing temperature of YBCO down to 750 °C. We investigated the influence of the growing temperatures on both the microstructure and superconducting properties of YBCO films by using conventional thermal annealing and flash-heating approaches. A clear correlation between the growing temperature (Tg) and the superconducting performance of the films was obtained with improved performances observed at low Tg.

Published
2021

19. Vortex pinning properties at dc and microwave frequencies of YBa2Cu3O7-x films with nanorods and nanoparticles

Author

European Commission, Ministerio de Economía y Competitividad (España), Generalitat de Catalunya, Bartolomé, Elena, Alcalà, Jordi, Vallés, Ferran, Puig Molina, Teresa, Obradors, Xavier, Pompeo, N., Alimenti, A., Torokhtii, K., Rizzo, Francesca, Augieri, A., Celentano, Giuseppe, Silva, E., Palau, Anna, European Commission, Ministerio de Economía y Competitividad (España), Generalitat de Catalunya, Bartolomé, Elena, Alcalà, Jordi, Vallés, Ferran, Puig Molina, Teresa, Obradors, Xavier, Pompeo, N., Alimenti, A., Torokhtii, K., Rizzo, Francesca, Augieri, A., Celentano, Giuseppe, Silva, E., and Palau, Anna

Abstract

YBa2Cu3O7−x (YBCO) nanocomposites for wire applications need to operate in a broad range of frequencies, ranging from dc in magnets to GHz in cavities and screenings of future particle accelerators. We have investigated the in-field and angular vortex pinning performance in dc and at 50 GHz of two types of nanocomposites, pulsed laser deposition (PLD) YBCO with mixed Ba2YNbO6 + Ba2YTaO6 (BYNTO) nanorods and chemical solution deposited (CSD) YBCO with BaHfO3 (BHO) nanoparticles (NPs), and the pristine counterpart films, grown on top of single-crystalline substrates. Transport measurements performed up to 9 T between 5 and 77 K show that CSD nanocomposites exhibit a smooth field decay and increased single-to-collective crossover field H* compared to pristine samples, associated to the enhanced isotropic pinning contribution induced by the NPs, while PLD films exhibit unchanged H* and superior critical current densities up to higher irreversibility fields, associated to the anisotropic contribution introduced by the rods. Microwave in-field measurements of the pinning constant kp revealed CSD NCs exhibit a qualitatively similar, but smoother kp(H) than pristine samples, whereas for PLD samples, a growing kp(H) dependence is observed as a result of the increased relevance of the stiffness of the fluxons pinned by nanorods.

Published
2020

26. Influence of growth temperature on the pinning landscape of YBa2Cu3O7−δ films grown from Ba-deficient solutions

Author

Jordi Alcalà, Pau Ternero, Cornelia Pop, Laura Piperno, Susagna Ricart, Narcís Mestres, Teresa Puig, Xavier Obradors, Alexander Meledin, Giuseppe Celentano, Anna Palau, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, European Cooperation in Science and Technology, Alcalà, Jordi, Obradors, Xavier, Celentano, Giuseppe, and Palau, Anna

Subjects
High-temperature superconductors, Materials Chemistry, Metals and Alloys, Ceramics and Composites, ddc:530, Electrical and Electronic Engineering, Condensed Matter Physics, Critical current density, Vortex pinning, Chemical solution deposition
Abstract

Cuprate coated conductors are promising materials for the development of large-scale applications, having superior performance over other superconductors. Tailoring their vortex pinning landscape through nanostructure engineering is one of the major challenges to fulfill the specific application requirements. In this work, we have studied the influence of the growth temperature on the generation of intrinsic pinning defects in YBa2Cu3O7-δ films grown by chemical solution deposition using low Ba precursor solutions. We have analysed the critical current density as a function of the temperature, applied magnetic field magnitude and orientation, J c(T,H,θ), to elucidate the nature and strength of pinning sites and correlate the microstructure of the films with their superconducting performance. An efficient pinning landscape consisting of stacking faults and associated nanostrain is naturally induced by simply tuning the growth temperature without the need to add artificial pinning sites. Samples grown at an optimized temperature of 750 °C show very high self-field J c values correlated with an overdoped state and improved J c(T,H,θ) performances., This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom Research and Training Programme 2014–2018 and 2019–2020 under Grant Agreement No. 633 053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. TEM analysis was funded from the EU Horizon 2020 research and innovation program under grant agreement 823717—ESTEEM3. The authors acknowledge financial support from Spanish Ministry of Economy and Competitiveness through the 'Severo Ochoa' Programme for Centres of Excellence in R&D (SEV-2015-0496 and CEX2019-000917-S), SuMaTe RTI2018-095853-B-C21, co-financed by the European Regional Development Fund), the Catalan Government with Grant 2017-SGR-1519 and the EU COST action NANOCOHYBRI CA16218. We also acknowledge the Scientific Services at ICMAB. J A like to thank the UAB PhD program in Materials Science., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Published
2022
Full Text
View/download PDF

27. Low-Fluorine Ba-Deficient Solutions for High-Performance Superconducting YBCO Films

Author

Anna Palau, Susagna Ricart, Cornelia Pop, Giuseppe Celentano, Teresa Puig, Giovanni Sotgiu, Narcis Mestres, Xavier Obradors, Laura Piperno, Pau Ternero, Jordi Alcalà, Ternero, Pau, Alcal??, Jordi, Piperno, Laura, Pop, Cornelia, Ricart, Susagna, Mestres, Narci, Obradors, Xavier, Puig, Teresa, Sotgiu, Giovanni, Celentano, Giuseppe, Palau, Anna, European Commission, Ministerio de Economía y Competitividad (España), European Cooperation in Science and Technology, Generalitat de Catalunya, and Alcalà, Jordi

Subjects
Chemical solution deposition, Materials science, High-temperature superconductivity, chemistry.chemical_element, 02 engineering and technology, 01 natural sciences, law.invention, law, High-temperature superconductors, vortex pinning, 0103 physical sciences, Materials Chemistry, Composite material, 010306 general physics, Superconductivity, Surfaces and Interfaces, high-temperature superconductor, 021001 nanoscience & nanotechnology, Microstructure, Critical current density, high-temperature superconductors, chemical solution deposition, Surfaces, Coatings and Films, chemistry, lcsh:TA1-2040, Fluorine, 0210 nano-technology, Vortex pinning, lcsh:Engineering (General). Civil engineering (General), critical current density
Abstract

High-performing superconducting YBa2Cu3O7–x (YBCO) films are fabricated by a chemical solution deposition methodology through novel barium-deficient low-fluorine solutions. The precursor solutions, distinguished for being straightforward, inexpensive and eco-friendly, allow us to reduce the growing temperature of YBCO down to 750 °C. We investigated the influence of the growing temperatures on both the microstructure and superconducting properties of YBCO films by using conventional thermal annealing and flash-heating approaches. A clear correlation between the growing temperature (Tg) and the superconducting performance of the films was obtained with improved performances observed at low Tg., This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom Research and Training Programme 2014–2018 and 2019–2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. We acknowledge financial support from Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496, FUNFUTURE CEX2019-000917-S), SUMATE project RTI2018-095853-B-C21, cofinanced by the European Regional Development Fund, COST-Nanocohybri CA16218 and Catalan Government with 2017-SGR-1519 and XRE4S.

Published
2021

29. Chemical Synthesis of La 0.75 Sr 0.25 CrO 3 Thin Films for p -Type Transparent Conducting Electrodes.

Author

Machado P, Guzmán R, Morera RJ, Alcalà J, Palau A, Zhou W, and Coll M

Abstract

The imperative need for highly performant and stable p -type transparent electrodes based on abundant metals is stimulating the research on perovskite oxide thin films. Moreover, exploring the preparation of these materials with the use of cost-efficient and scalable solution-based techniques is a promising approach to extract their full potential. Herein, we present the design of a chemical route, based on metal nitrate precursors, for the preparation of pure phase La 0.75 Sr 0.25 CrO 3 (LSCO) thin films to be used as a p -type transparent conductive electrode. Different solution chemistries have been evaluated to ultimately obtain dense, epitaxial, and almost relaxed LSCO films. Optical characterization of the optimized LSCO films reveals promising high transparency with ∼67% transmittance while room temperature resistivity values are 1.4 Ω·cm. It is suggested that the presence of structural defects, i.e., antiphase boundaries and misfit dislocations, affects the electrical behavior of LSCO films. Monochromated electron energy loss spectroscopy allowed changes in the electronic structure in LSCO films to be determined, revealing the creation of Cr 4+ and unoccupied states at the O 2 p upon Sr-doping. This work offers a new venue to prepare and further investigate cost-effective functional perovskite oxides with potential to be used as p -type transparent conducting electrodes and be easily integrated in many oxide heterostructures., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results