Search

Your search keyword '"Valbuena, Miguel A."' showing total 112 results
Start Over Author "Valbuena, Miguel A." Publication Year Range Last 10 years
112 results on '"Valbuena, Miguel A."'

1. The role of rare-earth atoms in the anisotropy and antiferromagnetic exchange coupling at a hybrid metal-organic interface

Author

Blanco-Rey, María, Castrillo, Rodrigo, Ali, Khadiza, Gargiani, Pierluigi, Ilyn, Max, Gastaldo, Michele, Paradinas, Markos, Valbuena, Miguel A., Mugarza, Aitor, Ortega, J. Enrique, Schiller, Frederik, and Fernández, Laura

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Strongly Correlated Electrons
Abstract

Magnetic anisotropy and magnetic exchange interactions are crucial parameters that characterize the hybrid metal-organic interface, key component of an organic spintronic device. We show that the incorporation of 4$f$ RE atoms to hybrid metal-organic interfaces of CuPc/REAu$_2$ type (RE= Gd, Ho) constitutes a feasible approach towards on-demand magnetic properties and functionalities. The GdAu$_2$ and HoAu$_2$ substrates differ in their magnetic anisotropy behavior. Remarkably, the HoAu$_2$ surface boosts the inherent out-of-plane anisotropy of CuPc, owing to the match between the anisotropy axis of substrate and molecule. Furthermore, the presence of RE atoms leads to a spontaneous antiferromagnetic (AFM) exchange coupling at the interface, induced by the 3$d$-4$f$ superexchange interaction between the unpaired 3$d$ electron of CuPc and the 4$f$ electrons of the RE atoms. We show that 4$f$ RE atoms with unquenched quantum orbital momentum ($L$), as it is the case of Ho, induce an anisotropic interfacial exchange coupling., Comment: Main paper: 10 pages and 3 figures; Supplementary Material: 13 pages, 5 figures

Published
2024
Full Text
View/download PDF

2. Experimental demonstration of a magnetically induced warping transition in a topological insulator mediated by rare-earth surface dopants

Author

Cano, Beatriz Muñiz, Ferreiros, Yago, Pantaleón, Pierre A., Dai, Ji, Tallarida, Massimo, Figueroa, Adriana I., Marinova, Vera, Díez, Kevin García, Mugarza, Aitor, Valenzuela, Sergio O., Miranda, Rodolfo, Camarero, Julio, Guinea, Francisco, Silva-Guillén, Jose Angel, and Valbuena, Miguel A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Magnetic topological insulators (MTI) constitute a novel class of materials where the topologically protected band structure coexists with long-range ferromagnetic order, which can lead to the breaking of time-reversal symmetry (TRS), introducing a bandgap in the Dirac cone-shaped topological surface state (TSS). The gap opening in MITs has been predicted to be accompanied by a distortion in the TSS, evolving its warped shape from hexagonal to trigonal. In this work, we demonstrate such a transition by means of angle-resolved photoemission spectroscopy after the deposition of low concentrations of magnetic rare earths, namely Er and Dy, on the ternary three-dimensional prototypical topological insulator Bi$_2$Se$_2$Te. Signatures of the gap opening occurring as a consequence of the TRS breaking have also been observed, whose existence is supported by the observation of the aforementioned transition. Moreover, increasing the Er coverage results in a tunable p-type doping of the TSS. As a consequence, the Fermi level (E$_{\textrm{F}}$) of our Bi$_2$Se$_2$Te crystals can be gradually tuned towards the TSS Dirac point, and therefore to the magnetically induced bandgap; thus fulfilling two of the necessary prerequisites for the realization of the quantum anomalous Hall effect (QAHE) in this system. The experimental results are rationalized by a theoretical model where a magnetic Zeeman out-of-plane term is introduced in the hamiltonian governing the TSS band dispersion. Our results offer new strategies to control magnetic interactions with TSSs based on a simple approach and open up viable routes for the realization of the QAHE.

Published
2023
Full Text
View/download PDF

3. Rashba-like spin textures in Graphene promoted by ferromagnet-mediated Electronic-Hybridization with heavy metal

Author

Cano, Beatriz Muñiz, Gudín, Adrían, Sánchez-Barriga, Jaime, Clark, Oliver J., Anadón, Alberto, Díez, Jose Manuel, Olleros-Rodríguez, Pablo, Ajejas, Fernando, Arnay, Iciar, Jugovac, Matteo, Rault, Julien, Févre, Patrick Le, Bertran, François, Mazhjoo, Donya, Bihlmayer, Gustav, Blügel, Stefan, Miranda, Rodolfo, Camarero, Julio, Valbuena, Miguel Angel, and Perna, Paolo

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Epitaxial graphene/ferromagnetic metal (Gr/FM) heterostructures deposited onto heavy metals (HM) have been proposed for the realization of novel spintronic devices because of their perpendicular magnetic anisotropy and sizeable Dzyaloshinskii-Moriya interaction (DMI), allowing for both enhanced thermal stability and stabilization of chiral spin textures. However, establishing routes towards this goal requires the fundamental understanding of the microscopic origin of their unusual properties. Here, we elucidate the nature of the induced spin-orbit coupling (SOC) at Gr/Co interfaces on Ir. Through spin- and angle-resolved photoemission along with density functional theory, we show that the interaction of the HM with the C atomic layer via hybridization with the FM is the source of strong SOC in the Gr layer. Furthermore, our studies on ultrathin Co films underneath Gr reveal an energy splitting of $\sim$\,100 meV (negligible) for in-plane (out-of-plane) spin polarized Gr $\pi$ bands, consistent with a Rashba-SOC at the Gr/Co interface, which is either the fingerprint or the origin of the DMI. This mechanism vanishes at large Co thicknesses, where neither in-plane nor out-of-plane spin-orbit splitting is observed, indicating that Gr $\pi$ states are electronically decoupled from the HM. The present findings are important for future applications of Gr-based heterostructures in spintronic devices., Comment: 11 pages, 7 figures

Published
2022

4. A Molecular Approach for Engineering Interfacial Interactions in Magnetic-Topological Insulator Heterostructures

Author

Cuxart, Marc G., Valbuena, Miguel Angel, Robles, Roberto, Moreno, César, Bonell, Frédéric, Sauthier, Guillaume, Imaz, Inhar, Xu, Heng, Nistor, Corneliu, Barla, Alessandro, Gargiani, Pierluigi, Valvidares, Manuel, Maspoch, Daniel, Gambardella, Pietro, Valenzuela, Sergio O., and Mugarza, Aitor

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Chemical Physics
Abstract

Controlling interfacial interactions in magnetic/topological insulator heterostructures is a major challenge for the emergence of novel spin-dependent electronic phenomena. As for any rational design of heterostructures that rely on proximity effects, one should ideally retain the overall properties of each component while tuning interactions at the interface. However, in most inorganic interfaces interactions are too strong, consequently perturbing, and even quenching, both the magnetic moment and the topological surface states at each side of the interface. Here we show that these properties can be preserved by using ligand chemistry to tune the interaction of magnetic ions with the surface states. By depositing Co-based porphyrin and phthalocyanine monolayers on the surface of Bi$_2$Te$_3$ thin films, robust interfaces are formed that preserve undoped topological surface states as well as the pristine magnetic moment of the divalent Co ions. The selected ligands allow us to tune the interfacial hybridization within this weak interaction regime. These results, which are in stark contrast with the observed suppression of the surface state at the first quintuple layer of Bi$_2$Se$_3$ induced by the interaction with Co phthalocyanines, demonstrate the capability of planar metal-organic molecules to span interactions from the strong to the weak limit.

Published
2020
Full Text
View/download PDF

5. Atomically precise step grids for the engineering of helical states

Author

Ortega, J. Enrique, Vasseur, Guillaume, Piquero-Zulaica, Ignacio, Raoult, Julien, Valbuena, Miguel Angel, Schirone, Stefano, Matencio, Sonia, Mugarza, Aitor, and Lobo-Checa, Jorge

Subjects
Condensed Matter - Materials Science
Abstract

Conventional spin-degenerated surface electrons have been effectively manipulated by using organic and inorganic self-assembled nanoarrays as resonators. Step superlattices naturally assembled in vicinal surfaces are a particularly interesting case since they represent simple one-dimensional (1D) models for fundamental studies, and can imprint strong anisotropies in surface electron transport in real devices. Here we present the first realization of periodic resonator arrays on the BiAg2 atom-thick surface alloy with unprecedented atomic precision, and demonstrate their potential ability for tuning helical Rashba states. By employing curved crystals to select local vicinal planes we achieve tunable arrays of monoatomic steps with different morphology and orientation. Scanning the ultraviolet light beam on the curved surface during angle-resolved photoemission experiments allows one to unveil the scattering behavior of spin-textured helical states. In this way, we find coherent scattering of helical Rashba states from the step arrays, as well as step-density-dependent Rashba band shifts and spin-orbit splitting compared to the extended BiAg2 plane., Comment: 13 pages, 4 figures, 4 supplementary figures

Published
2019

7. Rashba-like Spin Textures in Graphene Promoted by Ferromagnet-Mediated Electronic Hybridization with a Heavy Metal

Author

Muñiz Cano, Beatriz, primary, Gudín, Adrián, additional, Sánchez-Barriga, Jaime, additional, Clark, Oliver, additional, Anadón, Alberto, additional, Díez, Jose Manuel, additional, Olleros-Rodríguez, Pablo, additional, Ajejas, Fernando, additional, Arnay, Iciar, additional, Jugovac, Matteo, additional, Rault, Julien, additional, Le Fèvre, Patrick, additional, Bertran, François, additional, Mazhjoo, Donya, additional, Bihlmayer, Gustav, additional, Rader, Oliver, additional, Blügel, Stefan, additional, Miranda, Rodolfo, additional, Camarero, Julio, additional, Valbuena, Miguel Angel, additional, and Perna, Paolo, additional

Published
2024
Full Text
View/download PDF

8. On‐Surface Synthesis of Organolanthanide Sandwich Complexes

Author

Mathialagan, Shanmugasibi K., primary, Parreiras, Sofia O., additional, Tenorio, Maria, additional, Černa, Lenka, additional, Moreno, Daniel, additional, Muñiz‐Cano, Beatriz, additional, Navío, Cristina, additional, Valvidares, Manuel, additional, Valbuena, Miguel A., additional, Urgel, José I., additional, Gargiani, Pierluigi, additional, Miranda, Rodolfo, additional, Camarero, Julio, additional, Martínez, José I., additional, Gallego, José M., additional, and Écija, David, additional

Published
2024
Full Text
View/download PDF

10. Atomically precise step grids for the engineering of helical states

Author

Ministerio de Ciencia e Innovación (España), Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Saint Petersburg State University, European Commission, Generalitat de Catalunya, Ortega, J. Enrique, Vasseur, Guillaume, Schiller, Frederik, Piquero-Zulaica, Ignacio, Weber, Andrew P., Raoult, Julien, Valbuena, Miguel A., Schirone, S., Matencio, Sonia, Sviatkin, Leonid A., Terenteva, Daria V., Koroteev, Yuri M., Chulkov, Eugene V., Mugarza, Aitor, Lobo-Checa, Jorge, Ministerio de Ciencia e Innovación (España), Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Saint Petersburg State University, European Commission, Generalitat de Catalunya, Ortega, J. Enrique, Vasseur, Guillaume, Schiller, Frederik, Piquero-Zulaica, Ignacio, Weber, Andrew P., Raoult, Julien, Valbuena, Miguel A., Schirone, S., Matencio, Sonia, Sviatkin, Leonid A., Terenteva, Daria V., Koroteev, Yuri M., Chulkov, Eugene V., Mugarza, Aitor, and Lobo-Checa, Jorge

Abstract

Conventional spin-degenerate surface electrons have been effectively manipulated by means of self-organized nano-arrays. Of particular interest are one-dimensional, step superlattices at vicinal surfaces, because their fundamental behavior can be understood through simple model theory, and they can be utilized to imprint strong surface anisotropies in electron transport devices. In this work, the realization of periodic resonator arrays on the BiAg2 atom-thick surface alloy with atomic precision is presented, and their potential ability for tailoring the giant-split helical Rashba states is demonstrated. By employing curved crystals to select local vicinal planes, two sharply defined arrays of BiAg2 monoatomic steps with distinct spacing are fabricated, as experimentally determined from scanning tunneling microscopy and low-energy electron diffraction. The interaction of the Rashba helical states with the step arrays is assessed by scanning the photon beam across the BiAg2 curved surface in angle-resolved photoemission experiments and comparing these results with density functional theory. Remarkably, strong orbital-selective renormalization of bands perpendicular to the step superlattice, as well as spin mixing of Rashba bands, are induced by the coherent scattering of the periodic step potential. These results pave the way to fabricate atomically precise coupled arrays of electron resonators to engineer spin-orbital textures.

Published
2024

12. Experimental Demonstration of a Magnetically Induced Warping Transition in a Topological Insulator Mediated by Rare-Earth Surface Dopants [Dataset]

Author

Valbuena, Miguel A. [miguelangel.valbuena@imdea.org], Muñiz, Beatriz, Ferreiros, Yago, Pantaleón, Pierre A., Dai, Ji, Tallarida, Massimo, Figueroa, Adriana I., Marinova, Vera, García-Díez, Kevin, Mugarza, Aitor, Valenzuela, Sergio O., Miranda, Rodolfo, Camarero, Julio, Guinea, F., Silva-Guillén, José Ángel, Valbuena, Miguel A., Valbuena, Miguel A. [miguelangel.valbuena@imdea.org], Muñiz, Beatriz, Ferreiros, Yago, Pantaleón, Pierre A., Dai, Ji, Tallarida, Massimo, Figueroa, Adriana I., Marinova, Vera, García-Díez, Kevin, Mugarza, Aitor, Valenzuela, Sergio O., Miranda, Rodolfo, Camarero, Julio, Guinea, F., Silva-Guillén, José Ángel, and Valbuena, Miguel A.

Abstract

Magnetic topological insulators constitute a novel class of materials whose topological surface states (TSSs) coexist with long-range ferromagnetic order, eventually breaking time-reversal symmetry. The subsequent bandgap opening is predicted to co-occur with a distortion of the TSS warped shape from hexagonal to trigonal. We demonstrate such a transition by means of angle-resolved photoemission spectroscopy on the magnetically rare-earth (Er and Dy) surface-doped topological insulator Bi2Se2Te. Signatures of the gap opening are also observed. Moreover, increasing the dopant coverage results in a tunable p-type doping of the TSS, thereby allowing for a gradual tuning of the Fermi level toward the magnetically induced bandgap. A theoretical model where a magnetic Zeeman out-of-plane term is introduced in the Hamiltonian governing the TSS rationalizes these experimental results. Our findings offer new strategies to control magnetic interactions with TSSs and open up viable routes for the realization of the quantum anomalous Hall effect.

Published
2023

13. Experimental Demonstration of a Magnetically Induced Warping Transition in a Topological Insulator Mediated by Rare-Earth Surface Dopants

Author

Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Comunidad de Madrid, European Commission, Muñiz, Beatriz [0000-0002-9338-7077], Figueroa, Adriana I. [0000-0002-8498-9383], Marinova, Vera [0000-0002-3499-0212], García-Díez, Kevin [0000-0001-8093-904X], Mugarza, Aitor [0000-0002-2698-885X], Valenzuela, Sergio O. [0000-0002-4632-8891], Camarero, Julio [0000-0003-0078-7280], Silva-Guillén, José Ángel [0000-0002-0483-5334], Valbuena, Miguel A. [0000-0002-0585-5636], Muñiz, Beatriz, Ferreiros, Yago, Pantaleón, Pierre A., Dai, Ji, Tallarida, Massimo, Figueroa, Adriana I., Marinova, Vera, García-Díez, Kevin, Mugarza, Aitor, Valenzuela, Sergio O., Miranda, Rodolfo, Camarero, Julio, Guinea, F., Silva-Guillén, José Ángel, Valbuena, Miguel A., Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Comunidad de Madrid, European Commission, Muñiz, Beatriz [0000-0002-9338-7077], Figueroa, Adriana I. [0000-0002-8498-9383], Marinova, Vera [0000-0002-3499-0212], García-Díez, Kevin [0000-0001-8093-904X], Mugarza, Aitor [0000-0002-2698-885X], Valenzuela, Sergio O. [0000-0002-4632-8891], Camarero, Julio [0000-0003-0078-7280], Silva-Guillén, José Ángel [0000-0002-0483-5334], Valbuena, Miguel A. [0000-0002-0585-5636], Muñiz, Beatriz, Ferreiros, Yago, Pantaleón, Pierre A., Dai, Ji, Tallarida, Massimo, Figueroa, Adriana I., Marinova, Vera, García-Díez, Kevin, Mugarza, Aitor, Valenzuela, Sergio O., Miranda, Rodolfo, Camarero, Julio, Guinea, F., Silva-Guillén, José Ángel, and Valbuena, Miguel A.

Abstract

Magnetic topological insulators constitute a novel class of materials whose topological surface states (TSSs) coexist with long-range ferromagnetic order, eventually breaking time-reversal symmetry. The subsequent bandgap opening is predicted to co-occur with a distortion of the TSS warped shape from hexagonal to trigonal. We demonstrate such a transition by means of angle-resolved photoemission spectroscopy on the magnetically rare-earth (Er and Dy) surface-doped topological insulator Bi2Se2Te. Signatures of the gap opening are also observed. Moreover, increasing the dopant coverage results in a tunable p-type doping of the TSS, thereby allowing for a gradual tuning of the Fermi level toward the magnetically induced bandgap. A theoretical model where a magnetic Zeeman out-of-plane term is introduced in the Hamiltonian governing the TSS rationalizes these experimental results. Our findings offer new strategies to control magnetic interactions with TSSs and open up viable routes for the realization of the quantum anomalous Hall effect.

Published
2023

15. 2D Co‐Directed Metal–Organic Networks Featuring Strong Antiferromagnetism and Perpendicular Anisotropy

Author

Parreiras, Sofia O., primary, Martín‐Fuentes, Cristina, additional, Moreno, Daniel, additional, Mathialagan, Shanmugasibi K., additional, Biswas, Kalyan, additional, Muñiz‐Cano, Beatriz, additional, Lauwaet, Koen, additional, Valvidares, Manuel, additional, Valbuena, Miguel A., additional, Urgel, José I., additional, Gargiani, Pierluigi, additional, Camarero, Julio, additional, Miranda, Rodolfo, additional, Martínez, José I., additional, Gallego, José M., additional, and Écija, David, additional

Published
2023
Full Text
View/download PDF

17. Experimental Demonstration of a Magnetically Induced Warping Transition in a Topological Insulator Mediated by Rare-Earth Surface Dopants

Author

Muñiz Cano, Beatriz, primary, Ferreiros, Yago, additional, Pantaleón, Pierre A., additional, Dai, Ji, additional, Tallarida, Massimo, additional, Figueroa, Adriana I., additional, Marinova, Vera, additional, García-Díez, Kevin, additional, Mugarza, Aitor, additional, Valenzuela, Sergio O., additional, Miranda, Rodolfo, additional, Camarero, Julio, additional, Guinea, Francisco, additional, Silva-Guillén, Jose Angel, additional, and Valbuena, Miguel A., additional

Published
2023
Full Text
View/download PDF

18. Experimental demonstration of a magnetically induced warping transition in a topological insulator mediated by rare-earth surface dopants

Author

Muñiz Cano, Beatriz, Ferreiros, Yago, Pantaleón, Pierre A., Dai, Ji, Tallarida, Massimo, Figueroa, Adriana I., Marinova, Vera, García Díez, Kevin, Mugarza, Aitor, Valenzuela, Sergio O., Miranda, Rodolfo, Camarero, Julio, Guinea, Francisco, Silva-Guillén, José Ángel, Valbuena, Miguel Ángel, Muñiz Cano, Beatriz, Ferreiros, Yago, Pantaleón, Pierre A., Dai, Ji, Tallarida, Massimo, Figueroa, Adriana I., Marinova, Vera, García Díez, Kevin, Mugarza, Aitor, Valenzuela, Sergio O., Miranda, Rodolfo, Camarero, Julio, Guinea, Francisco, Silva-Guillén, José Ángel, and Valbuena, Miguel Ángel

Published
2023

19. Data - Lanthanide metal–organic network featuring strong perpendicular magnetic anisotropy

Author

Parreiras, Sofia O., Moreno, Daniel, Mathialagan, Shanmugasibi K., Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Tenorio, María, Černa, Lenka, Urgel, José I., Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel Ángel, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Miranda, Rodolfo, Camarero, Julio, Écija, David, Parreiras, Sofia O., Moreno, Daniel, Mathialagan, Shanmugasibi K., Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Tenorio, María, Černa, Lenka, Urgel, José I., Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel Ángel, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Miranda, Rodolfo, Camarero, Julio, and Écija, David

Abstract

(i) Multiplet calculations for TDA+Er; (ii) Point charges for multiplet calculations for TDA+Er; (iii) STM images; (iv) STS data; (v) XAS, XMCD and XLD data for TDA+Er

Published
2023

20. Lanthanide metal–organic network featuring strong perpendicular magnetic anisotropy

Author

Parreiras, Sofía O., Moreno, Daniel, Mathialagan, Shanmugasibi K, Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Tenorio, María, Černa, Lenka, Urgel, José I., Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel Ángel, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Miranda, Rodolfo, Camarero, Julio, Écija, David, Parreiras, Sofía O., Moreno, Daniel, Mathialagan, Shanmugasibi K, Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Tenorio, María, Černa, Lenka, Urgel, José I., Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel Ángel, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Miranda, Rodolfo, Camarero, Julio, and Écija, David

Published
2023

21. Lanthanide metal-organic network featuring strong perpendicular magnetic anisotropy

Author

0000-0001-9009-1994, 0000-0002-4499-2561, 0000-0003-2910-7429, 0000-0002-9338-7077, 0000-0002-0632-1636, 0000-0001-7608-2979, 0000-0003-1024-6779, 0000-0002-0585-5636, 0000-0003-1716-0126, 0000-0002-2086-8603, 0000-0002-8661-8295, Parreiras, Sofia O, Moreno, Daniel, Mathialagan, Shanmugasibi K, Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Tenorio, María, Černa, Lenka, Urgel, José I, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel A, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Miranda, Rodolfo, Camarero, Julio, Écija, David, 0000-0001-9009-1994, 0000-0002-4499-2561, 0000-0003-2910-7429, 0000-0002-9338-7077, 0000-0002-0632-1636, 0000-0001-7608-2979, 0000-0003-1024-6779, 0000-0002-0585-5636, 0000-0003-1716-0126, 0000-0002-2086-8603, 0000-0002-8661-8295, Parreiras, Sofia O, Moreno, Daniel, Mathialagan, Shanmugasibi K, Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Tenorio, María, Černa, Lenka, Urgel, José I, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel A, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Miranda, Rodolfo, Camarero, Julio, and Écija, David

Abstract

The coordination of lanthanides atoms in two-dimensional surface-confined metal-organic networks is a promising path to achieve an ordered array of single atom magnets. These networks are highly versatile with plenty of combinations of molecular linkers and metallic atoms. Notably, with an appropriate choice of molecules and lanthanide atoms it should be feasible to tailor the orientation and intensity of the magnetic anisotropy. However, up to now only tilted and almost in-plane easy axis of magnetizations were reported in lanthanide-based architectures. Here we introduce an Er-directed two-dimensional metallosupramolecular network on Cu(111) featuring strong out-of-plane magnetic anisotropy. Our results will contribute to pave avenues for the use of lanthanides in potential applications in nanomagnetism and spintronics.

Published
2023

22. Two-dimensional Co-directed metal-organic networks featuring strong antiferromagnetism and perpendicular anisotropy

Author

European Research Council, Ministerio de Ciencia e Innovación (España), European Commission, Agencia Estatal de Investigación (España), Comunidad de Madrid, Gallego, José M. [0000-0003-1716-0126], Parreiras, Sofia O., Martín-Fuentes, Cristina, Moreno, Daniel, Mathialagan, Shanmugasibi K., Biswas, Kalyan, Muñiz-Cano, Beatriz, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel A., Urgel, José I., Gargiani, Pierluigi, Camarero, Jesús Julio, Miranda, Rodolfo, Martínez, José I., Gallego, José M., Écija, David, European Research Council, Ministerio de Ciencia e Innovación (España), European Commission, Agencia Estatal de Investigación (España), Comunidad de Madrid, Gallego, José M. [0000-0003-1716-0126], Parreiras, Sofia O., Martín-Fuentes, Cristina, Moreno, Daniel, Mathialagan, Shanmugasibi K., Biswas, Kalyan, Muñiz-Cano, Beatriz, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel A., Urgel, José I., Gargiani, Pierluigi, Camarero, Jesús Julio, Miranda, Rodolfo, Martínez, José I., Gallego, José M., and Écija, David

Abstract

Antiferromagnetic spintronics is a rapidly emerging field with the potential to revolutionize the way we store and process information. One of the key challenges in this field is the development of novel two-dimensional antiferromagnetic materials. In this paper, we report the first on-surface synthesis of a Co-directed metal-organic network in which the Co atoms are strongly antiferromagnetically coupled, while featuring a perpendicular magnetic anisotropy. This material is a promising candidate for future antiferromagnetic spintronic devices, as it combines the advantages of twodimensionality and metal-organic chemistry with strong antiferromagnetic order and perpendicular magnetic anisotropy.

Published
2023

23. Use of Reduced Gravity Simulators for Plant Biological Studies

Author

Herranz, Raúl, Valbuena, Miguel A., Manzano, Aránzazu, Kamal, Khaled Y., Villacampa, Alicia, Ciska, Malgorzata, van Loon, Jack J.W.A., Medina, F. Javier, Blancaflor, Elison B., Blancaflor, Elison B., AMS - Ageing & Vitality, AMS - Musculoskeletal Health, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), European Space Agency, Herranz, Raúl [0000-0002-0246-9449], Valbuena, Miguel A. [0000-0002-0585-5636], Manzano, Aranzazu [0000-0002-0150-0803], Kamal, Khaled Y. [0000-0002-6909-8056], Villacampa, Alicia [0000-0002-7398-8545], Ciska, Malgorzata [0000-0002-6514-9493], van Loon, Jack JWA [0000-0001-9051-6016], Medina, F. Javier [0000-0002-0866-7710], Maxillofacial Surgery (AMC + VUmc), Herranz, Raúl, Valbuena, Miguel A., Manzano, Aranzazu, Kamal, Khaled Y., Villacampa, Alicia, Ciska, Malgorzata, van Loon, Jack JWA, and Medina, F. Javier

Subjects
Large Diameter Centrifuge (LDC), Gravity (chemistry), Hypergravity, Biological studies, Reduced Gravity, Computer science, Microgravity Simulation, Spaceflight, Random positioning machine (RPM), law.invention, Seedlings, law, Magnetic levitation, Biochemical engineering, Cell suspension cultures, Space research, Clinostat
Abstract

28 p.-7 fig.-3 tab., Simulated microgravity and partial gravity research on Earth is a necessary complement to space research in real microgravity due to limitations of access to spaceflight. However, the use of ground-based facilities for reduced gravity simulation is far from simple. Microgravity simulation usually results in the need to consider secondary effects that appear in the generation of altered gravity. These secondary effects may interfere with gravity alteration in the changes observed in the biological processes under study. In addition to micro- gravity simulation, ground-based facilities are also capable of generating hypergravity or fractional gravity conditions whose effects on biological systems are worth being tested and compared with the results of microgravity exposure. Multiple technologies (2D clinorotation, random positioning machines, magnetic levitators, or centrifuges) and experimental hardware (different containers and substrates for seedlings or cell cultures) are available for these studies. Experimental requirements should be collectively and carefully considered in defining the optimal experimental design, taking into account that some environmental parameters, or life-support conditions, could be difficult to be provided in certain facilities. Using simula- tion facilities will allow us to anticipate, modify, or redefine the findings provided by the scarce available spaceflight opportunities., Work performed in the authors’ laboratory was financially supported by the Spanish Plan Estatal de Investigación Científica y Desarrollo Tecnológico, Grants #ESP2015-64323-R and #RTI2018-099309-B-I00 (co-funded by EU-ERDF) to F.J.M. and a grant from European Space Agency contract# 4000107455/12/NL/PA awarded to J.J.W.A.v.L.

Published
2021
Full Text
View/download PDF

24. Lanthanide metal–organic network featuring strong perpendicular magnetic anisotropy

Author

Parreiras, Sofia O., primary, Moreno, Daniel, additional, Mathialagan, Shanmugasibi K., additional, Muñiz-Cano, Beatriz, additional, Martín-Fuentes, Cristina, additional, Tenorio, María, additional, Černa, Lenka, additional, Urgel, José I., additional, Lauwaet, Koen, additional, Valvidares, Manuel, additional, Valbuena, Miguel A., additional, Gallego, José M., additional, Martínez, José I., additional, Gargiani, Pierluigi, additional, Miranda, Rodolfo, additional, Camarero, Julio, additional, and Écija, David, additional

Published
2023
Full Text
View/download PDF

25. Slow Magnetic Relaxation of Dy Adatoms with In-Plane Magnetic Anisotropy on a Two- Dimensional Electron Gas

Author

Bellini, Valerio, Rusponi, Stefano, Kolorenč, Jindřich, Mahatha, Sanjoy K., Valbuena, Miguel Ángel, Persichetti, Luca, Pivetta, Marina, Sorokin, Boris V., Merk, Darius, Reynaud, Sébastien, Sblendorio, Dante, Stepanow, Sebastian, Nistor, Corneliu, Gargiani, Pierluigi, Betto, Davide, Mugarza, Aitor, Gambardella, Pietro, Brune, Harald, Carbone, Carlo, Barla, Alessandro, Bellini, Valerio, Rusponi, Stefano, Kolorenč, Jindřich, Mahatha, Sanjoy K, Valbuena, Miguel Angel, Persichetti, Luca, Pivetta, Marina, Sorokin, Boris V, Merk, Dariu, Reynaud, Sébastien, Sblendorio, Dante, Stepanow, Sebastian, Nistor, Corneliu, Gargiani, Pierluigi, Betto, Davide, Mugarza, Aitor, Gambardella, Pietro, Brune, Harald, Carbone, Carlo, Barla, Alessandro, Consiglio Nazionale delle Ricerche, Czech Academy of Sciences, Swiss National Science Foundation, Generalitat de Catalunya, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), and Ministerio de Economía y Competitividad (España)

Subjects
perovskite oxides, Settore FIS/03, atoms, ray circular-dichroism, metal, Perovskite oxides, Slow magnetic relaxation, single atom magnets, X-ray magnetic circular dichroism, density functional theory, scattering, single atom magnet, slow magnetic relaxation, substrate electronic gas with electric fields. slow magnetic relaxation, srtio3, Condensed Matter::Materials Science, perovskite oxide, Single atom magnets, surface, strontium-titanate, beamline
Abstract

We report on the magnetic properties of Dy atoms adsorbed on the (001) surface of SrTiO3. X-ray magnetic circular dichroism reveals slow relaxation of the Dy magnetization on a time scale of about 800 s at 2.5 K, unusually associated with an easy-plane magnetic anisotropy. We attribute these properties to Dy atoms occupying hollow adsorption sites on the TiO2-terminated surface. Conversely, Ho atoms adsorbed on the same surface show paramagnetic behavior down to 2.5 K. With the help of atomic multiplet simulations and first-principles calculations, we establish that Dy populates also the top-O and bridge sites on the coexisting SrO-terminated surface. A simple magnetization relaxation model predicts these two sites to have an even longer magnetization lifetime than the hollow site. Moreover, the adsorption of Dy on the insulating SrTiO3 crystal leads, regardless of the surface termination, to the formation of a spin-polarized two-dimensional electron gas of Ti 3d(xy) character, together with an antiferromagnetic Dy-Ti coupling. Our findings support the feasibility of tuning the magnetic properties of the rare-earth atoms by acting on the substrate electronic gas with electric fields., ACS Nano, 16 (7), ISSN:1936-0851, ISSN:1936-086X

Published
2022
Full Text
View/download PDF

26. Use of reduced gravity simulators for plant biological studies

Author

Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), European Space Agency, Herranz, Raúl [0000-0002-0246-9449], Valbuena, Miguel A. [0000-0002-0585-5636], Manzano, Aranzazu [0000-0002-0150-0803], Kamal, Khaled Y. [0000-0002-6909-8056], Villacampa, Alicia [0000-0002-7398-8545], Ciska, Malgorzata [0000-0002-6514-9493], van Loon, Jack JWA [0000-0001-9051-6016], Medina, F. Javier [0000-0002-0866-7710], Herranz, Raúl, Valbuena, Miguel A., Manzano, Aranzazu, Kamal, Khaled Y., Villacampa, Alicia, Ciska, Malgorzata, van Loon, Jack JWA, Medina, F. Javier, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), European Space Agency, Herranz, Raúl [0000-0002-0246-9449], Valbuena, Miguel A. [0000-0002-0585-5636], Manzano, Aranzazu [0000-0002-0150-0803], Kamal, Khaled Y. [0000-0002-6909-8056], Villacampa, Alicia [0000-0002-7398-8545], Ciska, Malgorzata [0000-0002-6514-9493], van Loon, Jack JWA [0000-0001-9051-6016], Medina, F. Javier [0000-0002-0866-7710], Herranz, Raúl, Valbuena, Miguel A., Manzano, Aranzazu, Kamal, Khaled Y., Villacampa, Alicia, Ciska, Malgorzata, van Loon, Jack JWA, and Medina, F. Javier

Abstract

Simulated microgravity and partial gravity research on Earth is a necessary complement to space research in real microgravity due to limitations of access to spaceflight. However, the use of ground-based facilities for reduced gravity simulation is far from simple. Microgravity simulation usually results in the need to consider secondary effects that appear in the generation of altered gravity. These secondary effects may interfere with gravity alteration in the changes observed in the biological processes under study. In addition to micro- gravity simulation, ground-based facilities are also capable of generating hypergravity or fractional gravity conditions whose effects on biological systems are worth being tested and compared with the results of microgravity exposure. Multiple technologies (2D clinorotation, random positioning machines, magnetic levitators, or centrifuges) and experimental hardware (different containers and substrates for seedlings or cell cultures) are available for these studies. Experimental requirements should be collectively and carefully considered in defining the optimal experimental design, taking into account that some environmental parameters, or life-support conditions, could be difficult to be provided in certain facilities. Using simula- tion facilities will allow us to anticipate, modify, or redefine the findings provided by the scarce available spaceflight opportunities.

Published
2021

27. On-Surface Design of a 2D Cobalt-Organic Network Preserving Large Orbital Magnetic Moment

Author

Martín-Fuentes, Cristina, primary, Parreiras, Sofia O., additional, Urgel, José I., additional, Rubio-Giménez, Víctor, additional, Muñiz Cano, Beatriz, additional, Moreno, Daniel, additional, Lauwaet, Koen, additional, Valvidares, Manuel, additional, Valbuena, Miguel A., additional, Gargiani, Pierluigi, additional, Kuch, Wolfgang, additional, Camarero, Julio, additional, Gallego, José M., additional, Miranda, Rodolfo, additional, Martínez, José I., additional, Martí-Gastaldo, Carlos, additional, and Écija, David, additional

Published
2022
Full Text
View/download PDF

29. Engineering Periodic Dinuclear Lanthanide‐Directed Networks Featuring Tunable Energy Level Alignment and Magnetic Anisotropy by Metal Exchange (Small 22/2022)

Author

Moreno, Daniel, primary, Parreiras, Sofia O., additional, Urgel, José I., additional, Muñiz‐Cano, Beatriz, additional, Martín‐Fuentes, Cristina, additional, Lauwaet, Koen, additional, Valvidares, Manuel, additional, Valbuena, Miguel A., additional, Gallego, José M., additional, Martínez, José I., additional, Gargiani, Pierluigi, additional, Camarero, Julio, additional, Miranda, Rodolfo, additional, and Écija, David, additional

Published
2022
Full Text
View/download PDF

30. Engineering Periodic Dinuclear Lanthanide-Directed Networks Featuring Tunable Energy Level Alignment and Magnetic Anisotropy by Metal Exchange

Author

Moreno D., Parreiras S.O., Urgel J.I., Muñiz-Cano B., Martín-Fuentes C., Lauwaet K., Valvidares M., Valbuena, Miguel Ángel, Gallego J.M., Martínez J.I., Gargiani P., Camarero, Julio, Miranda, Rodolfo, Écija, David, Moreno D., Parreiras S.O., Urgel J.I., Muñiz-Cano B., Martín-Fuentes C., Lauwaet K., Valvidares M., Valbuena, Miguel Ángel, Gallego J.M., Martínez J.I., Gargiani P., Camarero, Julio, Miranda, Rodolfo, and Écija, David

Published
2022

31. Data - Tuning the Magnetic Anisotropy of Lanthanides on a Metal Substrate by Metal–Organic Coordination

Author

Parreiras, Sofía O., Moreno, Daniel, Cirera, Borja, Valbuena, Miguel Ángel, Urgel, José I., Paradinas, Markos, Panighel, Mirco, Ajejas, Fernando, Niño, Miguel A., Gallego, José M., Valvidares, Manuel, Gargiani, Pierluigi, Kuch, Wolfgang, Martínez, José I., Mugarza, Aitor, Camarero, Julio, Miranda, Rodolfo, Perna, Paolo, Écija, David, Parreiras, Sofía O., Moreno, Daniel, Cirera, Borja, Valbuena, Miguel Ángel, Urgel, José I., Paradinas, Markos, Panighel, Mirco, Ajejas, Fernando, Niño, Miguel A., Gallego, José M., Valvidares, Manuel, Gargiani, Pierluigi, Kuch, Wolfgang, Martínez, José I., Mugarza, Aitor, Camarero, Julio, Miranda, Rodolfo, Perna, Paolo, and Écija, David

Abstract

(i) Multiplet calculations for TDA+Dy, TPA+Dy, and antiprism+Dy; (ii) Point charges for multiplet calculations for TDA+Dy and TPA+Dy; (iii) STM images for TDA+Dy and TPA+D; (iv) STS data for TDA+Dy; (v) XAS, XMCD and XNLD data for TDA+Dy, TPA+Dy and Dy clusters

Published
2022

32. Data - Engineering Periodic Dinuclear Lanthanide-Directed Networks Featuring Tunable Energy Level Alignment and Magnetic Anisotropy by Metal Exchange

Author

Moreno, Daniel, Parreiras, Sofía O., Urgel, José I., Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel Ángel, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Camarero, Julio, Miranda, Rodolfo, Écija, David, Moreno, Daniel, Parreiras, Sofía O., Urgel, José I., Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel Ángel, Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Camarero, Julio, Miranda, Rodolfo, and Écija, David

Abstract

(i) Multiplet calculations for DPBP+Dy and DPBP+Er; (ii) Point charges for multiplet calculations for DPBP+Dy and DPBP+Er; (iii) STM images for DPBP+Dy and DPBP+Er; (iv) STS data for DPBP+Dy and DPBP+Er; (v) XAS, XMCD and XLD data for DPBP+Dy and DPBP+Er

Published
2022

33. Slow Magnetic Relaxation of Dy Adatoms with In-Plane Magnetic Anisotropy on a Two-Dimensional Electron Gas

Author

Consiglio Nazionale delle Ricerche, Academy of Sciences of the Czech Republic, Swiss National Science Foundation, Generalitat de Catalunya, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Bellini, Valerio, Rusponi, S., Kolorenč, Jindřich, Mahatha, Sanjoy K., Valbuena, Miguel A., Persichetti, Luca, Pivetta, Marina, Sorokin, Boris V., Merk, Darius, Reynaud, Sébastien, Sblendorio, Dante, Stepanow, Sebastian, Nistor, Corneliu, Gargiani, Pierluigi, Betto, D., Mugarza, Aitor, Gambardella, Pietro, Brune, H., Carbone, Carlo, Barla, Alessandro, Consiglio Nazionale delle Ricerche, Academy of Sciences of the Czech Republic, Swiss National Science Foundation, Generalitat de Catalunya, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Bellini, Valerio, Rusponi, S., Kolorenč, Jindřich, Mahatha, Sanjoy K., Valbuena, Miguel A., Persichetti, Luca, Pivetta, Marina, Sorokin, Boris V., Merk, Darius, Reynaud, Sébastien, Sblendorio, Dante, Stepanow, Sebastian, Nistor, Corneliu, Gargiani, Pierluigi, Betto, D., Mugarza, Aitor, Gambardella, Pietro, Brune, H., Carbone, Carlo, and Barla, Alessandro

Abstract

We report on the magnetic properties of Dy atoms adsorbed on the (001) surface of SrTiO3. X-ray magnetic circular dichroism reveals slow relaxation of the Dy magnetization on a time scale of about 800 s at 2.5 K, unusually associated with an easy-plane magnetic anisotropy. We attribute these properties to Dy atoms occupying hollow adsorption sites on the TiO2-terminated surface. Conversely, Ho atoms adsorbed on the same surface show paramagnetic behavior down to 2.5 K. With the help of atomic multiplet simulations and first-principles calculations, we establish that Dy populates also the top-O and bridge sites on the coexisting SrO-terminated surface. A simple magnetization relaxation model predicts these two sites to have an even longer magnetization lifetime than the hollow site. Moreover, the adsorption of Dy on the insulating SrTiO3 crystal leads, regardless of the surface termination, to the formation of a spin-polarized two-dimensional electron gas of Ti 3dxy character, together with an antiferromagnetic Dy-Ti coupling. Our findings support the feasibility of tuning the magnetic properties of the rare-earth atoms by acting on the substrate electronic gas with electric fields.

Published
2022

34. Engineering Periodic Dinuclear Lanthanide-Directed Networks Featuring Tunable Energy Level Alignment and Magnetic Anisotropy by Metal Exchange

Author

European Research Council, European Commission, Moreno, Daniel, Parreiras, Sofia O., Urgel, José I., Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel A., Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Camarero, Jesús Julio, Miranda, Rodolfo, Écija, David, European Research Council, European Commission, Moreno, Daniel, Parreiras, Sofia O., Urgel, José I., Muñiz-Cano, Beatriz, Martín-Fuentes, Cristina, Lauwaet, Koen, Valvidares, Manuel, Valbuena, Miguel A., Gallego, José M., Martínez, José I., Gargiani, Pierluigi, Camarero, Jesús Julio, Miranda, Rodolfo, and Écija, David

Abstract

[EN] The design of lanthanide multinuclear networks is an emerging field of research due to the potential of such materials for nanomagnetism, spintronics, and quantum information. Therefore, controlling their electronic and magnetic properties is of paramount importance to tailor the envisioned functionalities. In this work, a multidisciplinary study is presented combining scanning tunneling microscopy, scanning tunneling spectroscopy, X-ray absorption spectroscopy, X-ray linear dichroism, X-ray magnetic circular dichroism, density functional theory, and multiplet calculations, about the supramolecular assembly, electronic and magnetic properties of periodic dinuclear 2D networks based on lanthanide-pyridyl interactions on Au(111). Er- and Dy-directed assemblies feature identical structural architectures stabilized by metal–organic coordination. Notably, despite exhibiting the same +3 oxidation state, there is a shift of the energy level alignment of the unoccupied molecular orbitals between Er- and Dy-directed networks. In addition, there is a reorientation of the easy axis of magnetization and an increment of the magnetic anisotropy when the metallic center is changed from Er to Dy. Thus, the results show that it is feasible to tune the energy level alignment and magnetic anisotropy of a lanthanide-based metal-organic architecture by metal exchange, while preserving the network design.

Published
2022

35. The FixBox: hardware to provide on-orbit fixation capabilities to the EMCS on the ISS

Author

Ministerio de Ciencia e Innovación (España), Ministerio de Economía y Competitividad (España), NASA Astrobiology Institute (US), European Space Agency, Manzano, Aranzazu [0000-0002-0150-0803], Tomás, Albert [0000-0001-9835-8825], Valbuena, Miguel A. [0000-0002-0585-5636], Villacampa, Alicia [0000-0002-7398-8545], Ciska, Malgorzata [0000-0002-6514-9493], Edelmann, Richard E. [0000-0002-8316-526X], Kiss, John Z. [0000-0003-1326-127X], Medina, F. Javier [0000-0002-0866-7710], Herranz, Raúl [0000-0002-0246-9449], Manzano, Aranzazu, Creus, Eva, Tomás, Albert, Valbuena, Miguel A., Villacampa, Alicia, Ciska, Malgorzata, Edelmann, Richard E., Kiss, John Z., Medina, F. Javier, Herranz, Raúl, Ministerio de Ciencia e Innovación (España), Ministerio de Economía y Competitividad (España), NASA Astrobiology Institute (US), European Space Agency, Manzano, Aranzazu [0000-0002-0150-0803], Tomás, Albert [0000-0001-9835-8825], Valbuena, Miguel A. [0000-0002-0585-5636], Villacampa, Alicia [0000-0002-7398-8545], Ciska, Malgorzata [0000-0002-6514-9493], Edelmann, Richard E. [0000-0002-8316-526X], Kiss, John Z. [0000-0003-1326-127X], Medina, F. Javier [0000-0002-0866-7710], Herranz, Raúl [0000-0002-0246-9449], Manzano, Aranzazu, Creus, Eva, Tomás, Albert, Valbuena, Miguel A., Villacampa, Alicia, Ciska, Malgorzata, Edelmann, Richard E., Kiss, John Z., Medina, F. Javier, and Herranz, Raúl

Abstract

Plant biology is an important area for the future of space exploration, but biological spaceflight experiments have been always constrained by the hardware capabilities. The European Modular Cultivation System (EMCS) unit was an incubator for small organisms, such as Arabidopsis thaliana, built by the European Space Agency (ESA) and was decommissioned in 2018. Here, we describe the FixBox system as add-on hardware to provide fixation capabilities to the plant growth cassettes, which, initially, were not designed to be used for that purpose. Tests were performed to ensure the successful use of this device in the EMCS facility. We also evaluate the required adaptations to the hardware, e.g., to guarantee that the reduced fluid motion in microgravity does not cause any bubbles that could impair the quality of fixation. Arabidopsis thaliana seedlings grown during spaceflight were fixed in the FixBox either in glutaraldehyde or formaldehyde. Electron microscopical images and confocal microscopy immunofluorescent localizations showed an excellent preservation of both cell ultrastructure and antigen conformation. Thus, it is possible to modify existing hardware to comply with the scientific requirements to augment the existing capabilities on board the ISS. In addition, it is also possible to reuse culture chambers from predesigned experimental containers into new modular subunits as FixBox. Similarly, we can design new hardware compatible with a novel cultivation chamber on board, such as is available in BIOLAB, to be used later with FixBox. Lessons learned for future space plant biology researchers include how to manage the number of hardware requirements and constraints on how to preserve the biological samples.

Published
2020

37. Tuning the Magnetic Anisotropy of Lanthanides on a Metal Substrate by Metal–Organic Coordination (Small 35/2021)

Author

Parreiras, Sofia O., primary, Moreno, Daniel, additional, Cirera, Borja, additional, Valbuena, Miguel A., additional, Urgel, José I., additional, Paradinas, Markos, additional, Panighel, Mirco, additional, Ajejas, Fernando, additional, Niño, Miguel A., additional, Gallego, José M., additional, Valvidares, Manuel, additional, Gargiani, Pierluigi, additional, Kuch, Wolfgang, additional, Martínez, José I., additional, Mugarza, Aitor, additional, Camarero, Julio, additional, Miranda, Rodolfo, additional, Perna, Paolo, additional, and Écija, David, additional

Published
2021
Full Text
View/download PDF

38. Tuning the Magnetic Anisotropy of Lanthanides on a Metal Substrate by Metal–Organic Coordination

Author

Parreiras S.O., Moreno D., Cirera B., Valbuena, Miguel Ángel, Urgel J.I., Paradinas M., Panighel M., Ajejas F., Niño M.A., Gallego J.M., Valvidares M., Gargiani P., Kuch W., Martínez J.I., Mugarza A., Camarero, Julio, Miranda, Rodolfo, Perna, Paolo, Écija, David, Parreiras S.O., Moreno D., Cirera B., Valbuena, Miguel Ángel, Urgel J.I., Paradinas M., Panighel M., Ajejas F., Niño M.A., Gallego J.M., Valvidares M., Gargiani P., Kuch W., Martínez J.I., Mugarza A., Camarero, Julio, Miranda, Rodolfo, Perna, Paolo, and Écija, David

Published
2021

39. Tuning the Magnetic Anisotropy of Lanthanides on a Metal Substrate by Metal–Organic Coordination

Author

European Commission, Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Parreiras, S. O., Moreno, Daniel, Cirera, Borja, Valbuena, Miguel A., Urgel, José I., Paradinas, Markos, Ajejas, Fernando, Niño, Miguel Ángel, Gallego, José M., Valvidares, Manuel, Gargiani, Pierluigi, Kuch, Wolfgang, Martínez, José I., Mugarza, Aitor, Camarero, Jesús Julio, Miranda, Rodolfo, Perna, Paolo, Écija, David, European Commission, Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Parreiras, S. O., Moreno, Daniel, Cirera, Borja, Valbuena, Miguel A., Urgel, José I., Paradinas, Markos, Ajejas, Fernando, Niño, Miguel Ángel, Gallego, José M., Valvidares, Manuel, Gargiani, Pierluigi, Kuch, Wolfgang, Martínez, José I., Mugarza, Aitor, Camarero, Jesús Julio, Miranda, Rodolfo, Perna, Paolo, and Écija, David

Abstract

Taming the magnetic anisotropy of lanthanides through coordination environments is crucial to take advantage of the lanthanides properties in thermally robust nanomaterials. In this work, the electronic and magnetic properties of Dy-carboxylate metal–organic networks on Cu(111) based on an eightfold coordination between Dy and ditopic linkers are inspected. This surface science study based on scanning probe microscopy and X-ray magnetic circular dichroism, complemented with density functional theory and multiplet calculations, reveals that the magnetic anisotropy landscape of the system is complex. Surface-supported metal–organic coordination is able to induce a change in the orientation of the easy magnetization axis of the Dy coordinative centers as compared to isolated Dy atoms and Dy clusters, and significantly increases the magnetic anisotropy. Surprisingly, Dy atoms coordinated in the metallosupramolecular networks display a nearly in-plane easy magnetization axis despite the out-of-plane symmetry axis of the coordinative molecular lattice. Multiplet calculations highlight the decisive role of the metal–organic coordination, revealing that the tilted orientation is the result of a very delicate balance between the interaction of Dy with O atoms and the precise geometry of the crystal field. This study opens new avenues to tailor the magnetic anisotropy and magnetic moments of lanthanide elements on surfaces.

Published
2021

40. Molecular Approach for Engineering Interfacial Interactions in Magnetic/Topological Insulator Heterostructures

Author

Cuxart, Marc G., primary, Valbuena, Miguel Angel, additional, Robles, Roberto, additional, Moreno, César, additional, Bonell, Frédéric, additional, Sauthier, Guillaume, additional, Imaz, Inhar, additional, Xu, Heng, additional, Nistor, Corneliu, additional, Barla, Alessandro, additional, Gargiani, Pierluigi, additional, Valvidares, Manuel, additional, Maspoch, Daniel, additional, Gambardella, Pietro, additional, Valenzuela, Sergio O., additional, and Mugarza, Aitor, additional

Published
2020
Full Text
View/download PDF

41. Towards microscopic control of the magnetic exchange coupling at the surface of a topological insulator

Author

German Research Foundation, Helmholtz Association, Ministero dell'Istruzione, dell'Università e della Ricerca, Russian Science Foundation, Generalitat de Catalunya, European Commission, Ministerio de Economía y Competitividad (España), Rüßmann, Philipp [0000-0002-6196-2700], Valbuena, Miguel A. [0000-0002-0585-5636], Mugarza, Aitor [0000-0002-2698-885X], Gargiani, Pierluigi [0000-0002-6649-0538], Valvidares, Manuel [0000-0003-4895-8114], Brookes, Nicholas B. [0000-0002-1342-9530], Bihlmayer, Gustav [0000-0002-6615-1122], Mavropoulos, Phivos [0000-0002-0205-8025], Barla, Alessandro [0000-0002-5632-4915], Rüßmann, Philipp, Mahatha, Sanjoy K., Sessi, Paolo, Valbuena, Miguel A., Bathon, Thomas, Fauth, Kai, Godey, Sylvie, Mugarza, Aitor, Kokh, Konstantin A., Tereshchenko, Oleg E., Gargiani, Pierluigi, Valvidares, Manuel, Jiménez, Erika, Brookes, Nicholas B., Bode, Matthias, Bihlmayer, Gustav, Blügel, Stefan, Mavropoulos, Phivos, Carbone, Carlo, Barla, Alessandro, German Research Foundation, Helmholtz Association, Ministero dell'Istruzione, dell'Università e della Ricerca, Russian Science Foundation, Generalitat de Catalunya, European Commission, Ministerio de Economía y Competitividad (España), Rüßmann, Philipp [0000-0002-6196-2700], Valbuena, Miguel A. [0000-0002-0585-5636], Mugarza, Aitor [0000-0002-2698-885X], Gargiani, Pierluigi [0000-0002-6649-0538], Valvidares, Manuel [0000-0003-4895-8114], Brookes, Nicholas B. [0000-0002-1342-9530], Bihlmayer, Gustav [0000-0002-6615-1122], Mavropoulos, Phivos [0000-0002-0205-8025], Barla, Alessandro [0000-0002-5632-4915], Rüßmann, Philipp, Mahatha, Sanjoy K., Sessi, Paolo, Valbuena, Miguel A., Bathon, Thomas, Fauth, Kai, Godey, Sylvie, Mugarza, Aitor, Kokh, Konstantin A., Tereshchenko, Oleg E., Gargiani, Pierluigi, Valvidares, Manuel, Jiménez, Erika, Brookes, Nicholas B., Bode, Matthias, Bihlmayer, Gustav, Blügel, Stefan, Mavropoulos, Phivos, Carbone, Carlo, and Barla, Alessandro

Abstract

Magnetically doped topological insulators may produce novel states of electronic matter, where for instance the quantum anomalous Hall effect state can be realized. Pivotal to this goal is a microscopic control over the magnetic state, defined by the local electronic structure of the dopants and their interactions. We report on the magnetic coupling among Mn or Co atoms adsorbed on the surface of the topological insulator Bi2Te3. Our findings uncover the mechanisms of the exchange coupling between magnetic atoms coupled to the topological surface state in strong topological insulators. The combination of x-ray magnetic circular dichroism and ab initio calculations reveals that the sign of the magnetic coupling at short adatom–adatom distances is opposite for Mn with respect to Co. For both elements, the magnetic exchange reverses its sign at a critical distance between magnetic adatoms, as a result of the interplay between superexchange, double exchange and Ruderman–Kittel–Kasuya–Yoshida interactions.

Published
2018

42. Influence of 4f filling on electronic and magnetic properties of rare earth-Au surface compounds

Author

Fernandez Gomez-Recuero, Laura, Blanco Rey, Maria, Castrillo-Bodero, R., Ilyn, M., Ali, Khadiza, Turco, Elia, Corso, Martina, Ormaza, Maider, Gargiani, Pierluigi, Valbuena, Miguel Ángel, Mugarza, Aitor, Moras, Paolo, Sheverdyaeva, Polina, Kundu, Asish K., Jugovac, Matteo, Laubschat, C., Ortega Conejero, Enrique, Schiller, Frederik, Fernandez Gomez-Recuero, Laura, Blanco Rey, Maria, Castrillo-Bodero, R., Ilyn, M., Ali, Khadiza, Turco, Elia, Corso, Martina, Ormaza, Maider, Gargiani, Pierluigi, Valbuena, Miguel Ángel, Mugarza, Aitor, Moras, Paolo, Sheverdyaeva, Polina, Kundu, Asish K., Jugovac, Matteo, Laubschat, C., Ortega Conejero, Enrique, and Schiller, Frederik

Abstract

Altres ajuts: This work was supported in part by the Basque Government Project IT-1255-19, and University of the Basque Country (UPV/EHU) grant GIU18/138 and the European Regional Development Fund (ERDF) under the program Interreg V-A España-Francia-Andorra (Contract No. EFA 194/16 TNSI)., One-atom-thick rare-earth/noble metal (RE-NM) compounds are attractive materials to investigate two-dimensional magnetism, since they are easy to synthesize into a common RE-NM2 structure with high crystal perfection. Here we perform a comparative study of the GdAu2, HoAu2, and YbAu2 monolayer compounds grown on Au(111). We find the same atomic lattice quality and moiré superlattice periodicity in the three cases, but different electronic properties and magnetism. The YbAu2 monolayer reveals the characteristic electronic signatures of a mixed-valence configuration in the Yb atom. In contrast, GdAu2 and HoAu2 show the trivalent character of the rare-earth and ferromagnetic transitions below 22 K. Yet, the GdAu2 monolayer has an in-plane magnetic easy-axis, versus the out-of-plane one in HoAu2. The electronic bands of the two trivalent compounds are very similar, while the divalent YbAu2 monolayer exhibits different band features. In the latter, a strong 4f-5d hybridization is manifested in neatly resolved avoided crossings near the Fermi level. First principles theory points to a residual presence of empty 4f states, explaining the fluctuating valence of Yb in the YbAu2 monolayer.

Published
2020

43. Influence of 4f filling on electronic and magnetic properties of rare earth-Au surface compounds

Author

Fernandez L., Blanco-Rey M., Castrillo-Bodero R., Ilyn M., Ali K., Turco E., Corso M., Ormaza M., Gargiani P., Valbuena, Miguel Ángel, Mugarza A., Moras P., Sheverdyaeva P.M., Kundu A.K., Jugovac M., Laubschat C., Ortega J.E., Schiller F., Fernandez L., Blanco-Rey M., Castrillo-Bodero R., Ilyn M., Ali K., Turco E., Corso M., Ormaza M., Gargiani P., Valbuena, Miguel Ángel, Mugarza A., Moras P., Sheverdyaeva P.M., Kundu A.K., Jugovac M., Laubschat C., Ortega J.E., and Schiller F.

Published
2020

44. Influence of 4f filling on electronic and magnetic properties of rare earth-Au surface compounds

Author

Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Universidad del País Vasco, Eusko Jaurlaritza, European Commission, Fernández, Laura, Blanco-Rey, María, Castrillo-Bodero, Rodrigo, Ilyn, Max, Ali, Khadiza, Turco, E., Corso, Martina, Ormaza, Maider, Gargiani, Pierluigi, Valbuena, Miguel A., Mugarza, Aitor, Moras, Paolo, Sheverdyaeva, P. M., Kundu, A. K., Jugovac, M., Laubschat, Clemens, Ortega, J. Enrique, Schiller, Frederik, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Universidad del País Vasco, Eusko Jaurlaritza, European Commission, Fernández, Laura, Blanco-Rey, María, Castrillo-Bodero, Rodrigo, Ilyn, Max, Ali, Khadiza, Turco, E., Corso, Martina, Ormaza, Maider, Gargiani, Pierluigi, Valbuena, Miguel A., Mugarza, Aitor, Moras, Paolo, Sheverdyaeva, P. M., Kundu, A. K., Jugovac, M., Laubschat, Clemens, Ortega, J. Enrique, and Schiller, Frederik

Abstract

One-atom-thick rare-earth/noble metal (RE-NM) compounds are attractive materials to investigate two-dimensional magnetism, since they are easy to synthesize into a common RE-NM2 structure with high crystal perfection. Here we perform a comparative study of the GdAu2, HoAu2, and YbAu2 monolayer compounds grown on Au(111). We find the same atomic lattice quality and moiré superlattice periodicity in the three cases, but different electronic properties and magnetism. The YbAu2 monolayer reveals the characteristic electronic signatures of a mixed-valence configuration in the Yb atom. In contrast, GdAu2 and HoAu2 show the trivalent character of the rare-earth and ferromagnetic transitions below 22 K. Yet, the GdAu2 monolayer has an in-plane magnetic easy-axis, versus the out-of-plane one in HoAu2. The electronic bands of the two trivalent compounds are very similar, while the divalent YbAu2 monolayer exhibits different band features. In the latter, a strong 4f–5d hybridization is manifested in neatly resolved avoided crossings near the Fermi level. First principles theory points to a residual presence of empty 4f states, explaining the fluctuating valence of Yb in the YbAu2 monolayer.

Published
2020

45. Atomically precise step grids for the engineering of helical states

Author

Generalitat de Catalunya, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Eusko Jaurlaritza, Gobierno de Aragón, European Commission, Ortega, J. Enrique, Vasseur, Guillaume, Piquero-Zulaica, Ignacio, Schiller, Frederik, Raoult, Julien, Valbuena, Miguel A., Schirone, S., Matencio, Sonia, Mugarza, Aitor, Lobo-Checa, Jorge, Generalitat de Catalunya, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Eusko Jaurlaritza, Gobierno de Aragón, European Commission, Ortega, J. Enrique, Vasseur, Guillaume, Piquero-Zulaica, Ignacio, Schiller, Frederik, Raoult, Julien, Valbuena, Miguel A., Schirone, S., Matencio, Sonia, Mugarza, Aitor, and Lobo-Checa, Jorge

Abstract

Conventional spin-degenerated surface electrons have been effectively manipulated by using organic and inorganic self-assembled nano-arrays as resonators. Step superlattices naturally assembled in vicinal surfaces are a particularly interesting case since they represent simple one-dimensional (1D) models for fundamental studies, and can imprint strong anisotropies in surface electron transport in real devices. Here we present the first realization of periodic resonator arrays on the BiAg2 atom-thick surface alloy with unprecedented atomic precision, and demonstrate their potential ability for tuning helical Rashba states. We employ a Ag cylindrical crystal curved around the Ag(645) vicinal surface [c-Ag(645) sample] to be able of selecting local vicinal planes with kinked steps. After sublimation and post-annealing of a 0.3 ML Bi layer, we achieve a homogenous BiAg2 surface alloy, featuring sharp arrays of extraordinarily straight Bi-terminated, monoatomic steps, with variable (tunable) density across the curved surface. Scanning the ultraviolet light beam on such Bi/c-Ag(645) interface in angle-resolved photoemission (ARPES) experiments allowed us to observe the characteristic signatures of strong and coherent step-lattice scattering in the spin-textured bands of the BiAg2 alloy, that is, step-umklapps, and a large, step-density-dependent Rashba band shift. First-principle DFT calculations reveal a complex terrace/step spin/orbital composition, which in turn explains the large spectral broadening and strong photon-energy dependence observed in ARPES. DFT also predicts the split-off of 1D electron-like step and terrace bands dispersing parallel to surface steps.

Published
2020

46. Molecular approach for engineering interfacial interactions in magnetic/topological insulator heterostructures

Author

Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, European Commission, European Research Council, Cuxart, M. G., Valbuena, Miguel A., Robles, Roberto, Moreno, César, Bonell, Fréderic, Sauthier, Guillaume, Imaz, Inhar, Xu, Heng, Nistor, Corneliu, Gargiani, Pierluigi, Valvidares, Manuel, Maspoch, Daniel, Gambardella, Pietro, Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, European Commission, European Research Council, Cuxart, M. G., Valbuena, Miguel A., Robles, Roberto, Moreno, César, Bonell, Fréderic, Sauthier, Guillaume, Imaz, Inhar, Xu, Heng, Nistor, Corneliu, Gargiani, Pierluigi, Valvidares, Manuel, Maspoch, Daniel, and Gambardella, Pietro

Abstract

Controlling interfacial interactions in magnetic/topological insulator heterostructures is a major challenge for the emergence of novel spin-dependent electronic phenomena. As for any rational design of heterostructures that rely on proximity effects, one should ideally retain the overall properties of each component while tuning interactions at the interface. However, in most inorganic interfaces, interactions are too strong, consequently perturbing, and even quenching, both the magnetic moment and the topological surface states at each side of the interface. Here, we show that these properties can be preserved using ligand chemistry to tune the interaction of magnetic ions with the surface states. By depositing Co-based porphyrin and phthalocyanine monolayers on the surface of Bi2Te3 thin films, robust interfaces are formed that preserve undoped topological surface states as well as the pristine magnetic moment of the divalent Co ions. The selected ligands allow us to tune the interfacial hybridization within this weak interaction regime. These results, which are in stark contrast with the observed suppression of the surface state at the first quintuple layer of Bi2Se3 induced by the interaction with Co phthalocyanines, demonstrate the capability of planar metal–organic molecules to span interactions from the strong to the weak limit.

Published
2020

47. Electronic properties and magnetic interaction of metal organic molecules on a monolayer thick GdAu2 substrate

Author

Castrillo-Bodero, R., Ilin, M., Fernández, Laura, Paradinas, Markos, Valbuena, Miguel A., Mugarza, Aitor, and Schiller, Frederik

Abstract

Trabajo presentado en el X Iberian Conference on Tribology y XI Iberian Vacuum Conference (IBERTRIVA) celebrada en Sevilla (España), del 26 al 28 de junio de 2019, Fundamental research on new states of the matter and technological applications in fields like spintronics (1) relays on the interfaces between magnetic materials and other states of the matter like superconductors, semiconductors or topological insulators. In the case of twodimensional (2D) ferromagnetic materials, it is necessary to keep the long-range magnetic order. To maintain this 2D magnetism the chemical and structural stability is mandatory. A molecular overlayer could influence these properties due to charge transfer. 2D rareearth/Noble-metal monolayer alloys show great potential as nanostructured magnetic patterns. Many of the lanthanides have shown already its potential by forming highly ordered corrugated structures when deposited on Au(111) and Ag(111) (2) nevertheless their magnetic and electronic structure after molecular deposition remains unknown. Here, we show evidence of the interaction between a GdAu2 monolayer alloy and magnetic molecules (metal centered porphyrin and phthalocyanines) that mutually influence their magnetic behavior. For example in the case of a one monolayer (ML) Co-tetraphenylporphyrin we observe a ferromagnetic interaction of the Co atom to the substrate, while the underlying material keeps basically its electronic and magnetic properties (Fig. 1). On the other hand a ML thick Co-phthalocyanine molecules film does not reveal any magnetic interaction. Only the second layer show a small magnetic signal.

Published
2019

49. Electronic and magnetic properties of phtalocyanine molecules on rare-earth noble-metal surfaces

Author

Fernández, Laura, Castrillo-Bodero, R., Blanco-Rey, María, Ali, Khadiza, Ilyn, Max, Gastaldo, M., Valbuena, Miguel A., Mugarza, Aitor, Ortega, J. Enrique, and Schiller, Frederik

Abstract

Trabajo presentado en Joint European Magnetic Symposia (JEMS), celebrado en Uppsala (Suecia), del 26 al 30 de agosto de 2019, Fundamental knowledge of magnetic and electronic interaction phenomena that takes place at the hybrid metalorganic interface is decisive to explore the possibility to create highly spin-polarized spinterfaces to enhance the performance of organic spintronic devices [1]. To this end, tailoring magnetic properties on structurally robust substrates is crucial. The survival of the long-range magnetic order upon interface formation is a basic requirement for one application type that intent to maintain the substrate magnetism and that is the reason why, besides structural stability and chemical inertness, substrate materials with strong ferromagnetism, i.e., high Curie temperatures TC are sought. For the survival of the magnetism of single molecular magnets, however, strong substrate ferromagnetism supresses all the desired properties of the molecules and there, a different type of magnetic substrates is needed. Rare-earth/noble metal monolayer alloys, grown on noble metal surfaces, possess a big potential as nanostructured magnetic templates with structural stability. Different elements of the lanthanide series have been observed to form surface-confined alloys in Au(111) [2], characterized by a high crystal quality and nanoscale periodic corrugation. In the case of the Gd-Au combination, by varying the Gd coverage, Moiré or trigon patterns can be tuned, which have been shown to drive the selforganized growth of ferromagnetic Co nanodot arrays. Notably, the Gd-Au templates remain structurally stable upon Co growth, allowing to trigger magnetic coupling of the Co nanodot array with the supporting Gd alloy [3]. Given the variety of REs and their exotic magnetism, the observations made on GdAu2 encouraged a thorough search combining different RE elements and noble metals. In this sense, a remarkable high Tc = 85 K in GdAg2 compared to Tc = 19 K in GdAu2 was recently observed [3]. It was show by photoemission experiments and by Density Functional Theory that magnetic coupling is effectively mediated by a noble metal-Gd hybrid s,p-d band giving rise to such a strong increase in Tc . On the other hand, our results of the magnetic properties in SmAu2 reveal completely different behaviour with respect to GdAu2, namely zero magnetic moment in the hard axis, while maintaining a ferromagnetic loop along the in-plane easy axis with a much lower Tc compared to the GdAu2. Here we will present experimental evidence based on photoemission and X-ray magnetic dichroism experiments that magnetic properties of the substrate and the magnetic molecules are influenced by each other depending on the strength of the magnetic moment of each contributor

Published
2019

50. Polarization dependence of angle-resolved photoemission with submicron spatial resolution reveals emerging one-dimensionality of electrons in NbSe3

Author

Valbuena, Miguel Ángel, Chudzinski P., Pons S., Conejeros S., Alemany P., Canadell E., Berger H., Frantzeskakis E., Ávila J., Asensio M.C., Giamarchi T., Grioni M., Valbuena, Miguel Ángel, Chudzinski P., Pons S., Conejeros S., Alemany P., Canadell E., Berger H., Frantzeskakis E., Ávila J., Asensio M.C., Giamarchi T., and Grioni M.

Published
2019

Catalog

Books, media, physical & digital resources
See catalog results