Química Física

Permanent URI for this collectionhttps://hdl.handle.net/10347/34406

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From Mechanisms to Materials: Oximate Reactivity and Emerging Strategies for Organophosphate Detoxification
(Wiley-VCH GmbH, 2026-04-19) Rodríguez Dafonte, Pedro; Universidade de Santiago de Compostela. Departamento de Química Física
The development of effective strategies for the detoxification of organophosphorus (OP) nerve agents has evolved from the early mechanistic studies of François Terrier and collaborators, who first elucidated the exceptional nucleophilicity of α-effect species such as oximes and hydroxamates, to the modern design of supramolecular and material-based systems. Terrier's pioneering kinetic investigations and the conceptual framework established by Clifford A. Bunton and Erwin Buncel on micellar catalysis provided a foundation for understanding how medium effects and local organization modulate α-nucleophile reactivity. Building on these insights, contemporary research has expanded the chemical landscape of oxime-based reactivators through synthetic modification, computational modeling, and the development of functional scaffolds capable of efficient acetylcholinesterase (AChE) reactivation and direct OP hydrolysis. This review examines the evolution of oxime-based detoxification, with emphasis on structure–reactivity relationships, mechanistic insights, and advances in reaction media. Micellar systems were the first colloidal environments explored, while supramolecular assemblies such as lipids and cyclodextrins combine molecular recognition with catalytic function. Recent developments include inorganic and nanostructured catalysts that enable organophosphate degradation under mild conditions. The transition from α-nucleophile chemistry to multifunctional materials reflects not only the progress of physical organic chemistry in detoxification but also its convergence with supramolecular and materials science.
Multi-omics reveals wastewater sludge bacteria with genomic potential to degrade poly(ethylene terephthalate)
(Elsevier, 2026-03) Vijande, Carlota; Balboa Méndez, Sabela; Lazzari, Massimo; Lema Rodicio, Juan Manuel; Pabst, Martin; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Departamento de Microbioloxía e Parasitoloxía; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
Plastic pollution is a growing concern, especially poly(ethylene terephthalate) (PET), one of the most produced plastic polymers. Although several microorganisms capable of degrading PET have been identified, little is known about those present in wastewater treatment plants (WWTPs). This study explores their ability to degrade PET and the enzymes involved. Activated sludge from two facilities—one urban WWTP and one industrial WWTP—was cultivated with PET of different crystallinities. The inoculum source primarily determined differences in microbial community composition. Metagenomics revealed more than 300 genes homologous to PET-degrading enzymes in all biofilms; however, metaproteomics confirmed expression of only a few of these enzymes in industrial WWTP-derived biofilms. This inoculum demonstrated the ability to degrade PET breakdown products within 24 h. In addition, FTIR analysis revealed initial signs of surface alteration. In conclusion, this study reveals the presence of microorganisms in industrial wastewater treatment sludge that possess the genetic potential to degrade PET.
Correlation between Microstructural and Magnetic Properties of Epitaxial YIG Films by Pulsed Laser Deposition
(ACS Publications, 2026-02-10) Costa, José Diogo; Adelmann, Christoph; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
In this study, we investigate the relationships among film growth conditions, crystalline microstructure, and magnetic properties of epitaxial yttrium iron garnet (Y3Fe5O12, YIG) thin films, deposited on gallium gadolinium garnet (Ga3Gd5O12, GGG). A direct correlation was observed between the residual epitaxial strain, bulk magnetic properties like effective magnetization and magnetic damping, and the performance of spin-wave transmission devices based on these films. This correlation offers a pathway for a simplified, rapid assessment of YIG film quality, avoiding the need for complex time-consuming characterization techniques. In addition, we report a comprehensive investigation into the influence of pulsed-laser deposition parameters, including deposition temperature, pressure, laser fluence, frequency, and annealing conditions. Through systematic deposition optimization, state-of-the-art YIG films exhibiting ultralow magnetic damping could be obtained, which is critical for high-performance spintronic applications
Inverse Conformational Selection in Lipid–Protein Binding
(American Chemical Society, 2021-08-16) Bacle, Amélie; García Fandiño, Rebeca; Ferreira, Tiago M.; Piñeiro Guillén, Ángel; Virtanen, Salla I.; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS); Universidade de Santiago de Compostela. Departamento de Física Aplicada
Interest in lipid interactions with proteins and other biomolecules is emerging not only in fundamental biochemistry but also in the field of nanobiotechnology where lipids are commonly used, for example, in carriers of mRNA vaccines. The outward-facing components of cellular membranes and lipid nanoparticles, the lipid headgroups, regulate membrane interactions with approaching substances, such as proteins, drugs, RNA, or viruses. Because lipid headgroup conformational ensembles have not been experimentally determined in physiologically relevant conditions, an essential question about their interactions with other biomolecules remains unanswered: Do headgroups exchange between a few rigid structures, or fluctuate freely across a practically continuous spectrum of conformations? Here, we combine solid-state NMR experiments and molecular dynamics simulations from the NMRlipids Project to resolve the conformational ensembles of headgroups of four key lipid types in various biologically relevant conditions. We find that lipid headgroups sample a wide range of overlapping conformations in both neutral and charged cellular membranes, and that differences in the headgroup chemistry manifest only in probability distributions of conformations. Furthermore, the analysis of 894 protein-bound lipid structures from the Protein Data Bank suggests that lipids can bind to proteins in a wide range of conformations, which are not limited by the headgroup chemistry. We propose that lipids can select a suitable headgroup conformation from the wide range available to them to fit the various binding sites in proteins. The proposed inverse conformational selection model will extend also to lipid binding to targets other than proteins, such as drugs, RNA, and viruses.
Computational insights into the chemical reaction networks of C3H6O3, C3H7O3 and C2H5O2: implications for the interstellar medium
(Royal Society of Chemistry, 2025-09-17) Lema Saavedra, Anxo; Fernández Ramos, Antonio; Martínez Núñez, Emilio; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
The formation of complex organic molecules (COMs) in the interstellar medium (ISM) is central to astrochemistry and prebiotic chemistry, as these species may act as precursors to biomolecules essential for life. Among COMs, glyceraldehyde (HOCH2CH(OH)C(O)H, GCA) has attracted attention as a potential building block in early biochemical pathways. Although GCA has not yet been detected in the ISM, the presence of structurally related compounds in various astronomical environments suggests that it may form under interstellar conditions. In this study, we employed the automated reaction discovery tool AutoMeKin to systematically explore the gas-phase chemical reaction networks (CRNs) of C3H6O3 (GCA), C3H7O3 (a hydrogenated analog), and C2H5O2. Reaction pathways were characterized at the oB97XD/Def2-TZVPP level of theory, and rate coefficients for key processes were computed using the competitive canonical unified statistical (CCUS) model, which accounts for multiple dynamic bottlenecks. Our analysis revealed several barrierless pathways leading to GCA or to GCA and a leaving group. Notably, the reaction between glyoxal (HCOHCO) and the HOCHCH2OH radical, though neither has yet been detected in the ISM, was found to efficiently produce GCA and a formyl radical, with rate coefficients on the order of 5.4–7.9 10 10 cm3 molecule 1 s 1 across the 10–100 K temperature range. However, aside from the aforementioned exception, most GCA formation channels result in highly vibrationally excited intermediates that are more likely to undergo rapid unimolecular decomposition than to be stabilized by radiative emission under typical ISM conditions. These results suggest that while gas-phase GCA formation is chemically feasible, it is likely transient and difficult to detect directly. In contrast, alternative products such as formaldehyde, glycolaldehyde, and (Z)-ethene-1,2-diol dominate many pathways and align better with current astronomical observations. This work provides detailed mechanistic and kinetic insights that enhance astrochemical modeling and advance our understanding of molecular complexity in star-forming environments. Furthermore, it highlights the utility of automated CRN exploration for uncovering viable synthetic routes to prebiotic molecules in space
Libro de Resumos da V Xuntanza de Investigador@s Nov@s no ámbito da química (XINQ_5)
(2025) Xuntanza Investigador@s Nov@s no ámbito da Química; Universidade de Santiago de Compostela. Facultade de Química; Martínez-Calvo, Miguel; Montes Goyanes, Rosa; Vázquez Vázquez, Carlos; Rumbo Gómez, Antonio
A XINQ é un espazo de encontro no que as investigadoras e investigadores novos que desenvolven o seu traballo no ámbito da química poden dalo a coñecer ao resto da comunidade universitaria. A xuntanza está pensada para que @s nov@s investigador@s entendan que se pode explicar a ciencia, a química no noso caso, en lingua galega ao mesmo tempo que desenvolven as súas capacidades de comunicación en público. A xuntanza desenvólvese a través dunha serie comunicacións orais de carácter divulgativo onde, en galego, expoñen os aspectos máis significativos e xerais da investigación que realizan no seu máster ou doutoramento. Nesta cuarta edición, o comité organizador considera que a XINQ se consolidou xa como un espazo para a difusión da investigación no ámbito da química na nosa universidade en galego. Nesta xuntanza pódense encontrar participantes procedentes da maioría dos centros de investigación e facultades da nosa institución, pero ten máis importancia, na nosa opinión, a participación de estudantes que non teñen o galego como lingua materna. El@s ofrécenos o exemplo da importancia que lle dan as persoas á lingua no proceso de integración e como ven nela un vinculo sentimental fundamental na nosa sociedade. Dende a Comisión de Normalización Lingüística da Facultade de Química débese reflexionar sobre a participación do seu profesorado nesta actividade. Sería positivo que en cada edición unha parella de profesores puidesen expoñer a investigación realizada ou un tema científico de actualidade de xeito divulgativo en lingua galega. Deste xeito, co tempo, poderían animarse a desenvolver a súa actividade docente en galego utilizado en pouca medida na nosa facultade.
POM-Based Water Splitting Catalyst Under Acid Conditions Driven by Its Assembly on Carbon Nanotubes
(Wiley, 2025-11-26) Quirós Díez, Eugenia Pilar; Guillén Soler, Melanie; Herreros Lucas, Carlos; López Moreno, Alejandro; Vila Fungueiriño, José Manuel; Llamas Saiz, Antonio Luis; Strutyński, Karol; Melle Franco, Manuel; Giménez López, María del Carmen; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS); Universidade de Santiago de Compostela. Departamento de Química Física
Development of efficient and stable bifunctional electrocatalysts for water electrolysis under acidic conditions is essential for sustainable hydrogen production. A novel vanadium polyoxometalate (POM)-based material, Na4(H2O)12[(CH2OH)3CNH3]2[V10O28]·4H2O (1) is presented, incorporating non-innocent cations and whose electrocatalytic activity can be switched from the production of oxygen to hydrogen through its assembly on carbon nanotubes (CNT). A physical mixture (1/CNT) shows remarkable oxygen evolution reaction (OER) activity, with an overpotential of 0.34 V at 10 mA cm−2, outperforming commercial IrO2 (0.45 V) and approaching Ir/C (0.31 V), with 80% Faradaic efficiency. In contrast, directed assembly (1@CNT) unlocks TRIS ⁺= [(CH2OH)3CNH3]⁺ groups functionality, enabling high hydrogen evolution reaction (HER) efficiency, with an onset potential of −0.07 V, close to Pt/C, and 94% Faradaic efficiency. Mechanistic studies, strongly supported by in-operando confocal microscopy and theoretical calculations, reveal that the modulation of crystal interactions and the local microenvironment is key to orchestrating the OER/HER tuning. OER is proposed to proceed via an alcohol oxidation reaction (AOR), while HER benefits from TRIS⁺ moieties acting as a “proton sponge”. This work provides a compelling approach for rational design of bifunctional molecular electrocatalysts based on earth-abundant elements and controlled nanoassembly, with clear relevance for advancing green hydrogen production technologies.
Polyimide-Linked Hexaazatriphenylene-Based Porous Organic Polymer with Multiple Redox-Active Sites as a High-Capacity Organic Cathode for Lithium-Ion Batteries
(Wiley, 2025-10-16) Mal, Arindam; Caroni, Jonathan; Patriarchi, Asia; Luzanin, Olivera; Ramos Amigo, Rafael Enrique; Bitenc, Jan; Melle Franco, Manuel; Souto Salom, Manuel; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
The development of high-capacity, sustainable cathode materials remains a critical challenge in advancing lithium-ion battery technologies for next-generation energy storage. Organic electrode materials (OEMs) represent a promising alternative to conventional inorganic cathodes, owing to their composition from earth-abundant elements and chemically tunable structures that enable high theoretical capacities. Herein, a polyimide-linked porous organic polymer (HAT-PTO) is reported to be synthesized via a straightforward hydrothermal reaction from redox-active hexaazatriphenylene (HAT) and pyrene-4,5,9,10-tetraone (PTO) building blocks. The resulting HAT-PTO framework incorporates multiple redox-active C═O and C═N centers, delivering a high theoretical capacity of 484 mAh g−1. To overcome limitations in electronic conductivity, hybrid materials are synthesized by in situ growth of HAT-PTO on multiwalled pristine (CNT) and carboxyl-functionalized carbon nanotubes (cCNT). Notably, the HAT-PTO-cCNT hybrid delivers a high capacity of 397 mAh g−1 at C/10, outstanding rate capability of 225 mAh g−1 at 20 C, and long-term cycling stability, retaining 171 mAh g−1 after 6000 cycles at 2 C. Ex situ FT-IR, supported by density functional theory (DFT) calculations, confirms the involvement of both HAT and PTO units in the charge storage mechanism. This work presents a molecular design strategy and scalable synthesis approach toward high-performance organic cathodes, paving the way for durable, high-rate lithium-organic batteries.
Microfluidics-Driven Manufacturing and Multiscale Analytical Characterization of Nanoparticle-Vesicle Hybrids
(Wiley, 2025-02-07) Cardellini, Jacopo; González Gómez, Manuel Antonio; Rivas Rey, José; Arosio, Paolo; Universidade de Santiago de Compostela. Departamento de Física Aplicada; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Instituto de Materiais (iMATUS)
Coating synthetic nanoparticles (NPs) with lipid membranes is a promising approach to enhance the performance of nanomaterials in various biological applications, including therapeutic delivery to target organs. Current methods for achieving this coating often rely on bulk approaches which can result in low efficiency and poor reproducibility. Continuous processes coupled with quality control represent an attractive strategy to manufacture products with consistent attributes and high yields. Here, this concept is implemented by developing an acoustic microfluidic device together with an analytical platform to prepare nanoparticle-vesicle hybrids and quantitatively characterize the nanoparticle coverage using fluorescence-based techniques at different levels of resolution. With this approach polymethyl methacrylate (PMMA) nanoparticles are successfully coated with liposomes and extracellular vesicles (EVs), achieving a high encapsulation efficiency of 70%. Moreover, the approach enables the identification of design rules to control the efficiency of encapsulation by tuning various operational parameters and material properties, including buffer composition, nanoparticle/vesicle ratio, and vesicle rigidity.
Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
(American Astronomical Society; IOP Publishing, 2026-03-11) Antiñolo, María; Benavente Martínez, Francisco Javier; González Fernández, Daniel; Lema Saavedra, Anxo; Martínez Núñez, Emilio; Fernández Ramos, Antonio; Agúndez Chico, Marcelino; Cernicharo Quintanilla, José; Jiménez Martínez, Elena; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
Sulfur-bearing molecules are key constituents of the interstellar medium (ISM). Particularly, hydrogen sulfide (H2S) and cyano (CN) radicals are key precursors of prebiotic molecules in the ISM. However, the ultralow-temperature gas-phase reactivity remains poorly characterized yet. We report the first experimental and theoretical investigation of the CN + H2S reaction under conditions relevant to cold molecular clouds. Rate coefficients were determined between 11.7 and 45.5 K using the Cinétique de Réaction en Ecoulement Supersonique Uniforme technique coupled with pulsed laser photolysis–laser-induced fluorescence, yielding negligible temperature dependence values around 4.0 × 10−10 cm3 s−1 in excellent agreement with complementary rate coefficients calculations. AutoMeKin and coupled-cluster theory reveal that the dominant channel involves CN addition to H2S, followed by H elimination, forming HSCN. This pathway is energetically more favorable than the previously assumed HCN + SH channel and exhibits submerged transition states, suggesting efficient reactivity at ultracold temperatures. Astrochemical modeling indicates that inclusion of this reaction in chemical networks enhances HSCN abundances in dark clouds, with contributions comparable to those from dissociative recombination routes. Although the CN + H2S reaction is absent from current astrochemical databases, our results demonstrate its potential role in sulfur–nitrogen coupling and the formation of prebiotic molecules in the ISM. These findings underscore the need to update chemical models to account for this process and improve predictions of sulfur chemistry in star-forming regions.
Red-Light-Driven C(sp2)–H Sulfonylation of Anilines Using a Recyclable Benzothiadiazole-Based Covalent Organic Framework
(ACS Publications, 2025-10-13) Alberca Manzano, Saúl; Nair, Akshay M.; Escamilla, Paula; Ferreira, Pedro; Souto Salom, Manuel; Fañanás-Mastral, Martín; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
The limitations of traditional high-energy (NUV or blue) photocatalysis, such as limited penetration in reaction media, off-target reactivity, and health hazards, have spurred the development of seminal red-light-mediated transformations. Despite recent advances, most homogeneous red-light photocatalysts suffer from poor recyclability, and recyclable heterogeneous systems remain underexplored. Herein, we report a red-light-driven C(sp2)–H sulfonylation of anilines using a highly stable benzothiadiazole-based covalent organic framework (Tp-BT COF) as an efficient, recyclable photocatalyst. The reaction proceeds under exceptionally mild conditions, affording sulfonylated products in good to excellent yields with minimal catalyst loading. Notably, the Tp-BT COF retains its catalytic activity over six consecutive cycles. Comparative studies with structurally related COFs highlight the critical role of the BT core in red-light absorption and the superior performance of the AA stacking mode. This work underscores the potential of rationally designed photoactive COFs for sustainable red-light photocatalysis
A general method for constructing and searching conformations in molecular rings: from cremer–pople coordinates to 3D geometries
(AIP Publishing, 2026-02-19) Lema Saavedra, Anxo; Fernández Ramos, Antonio; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS); Universidade de Santiago de Compostela. Departamento de Química Física
We present a general framework to construct and systematically search for ring conformations based on Cremer–Pople (CP) coordinates. To our knowledge, this is the first algorithm that provides reasonable ring geometries across different ring sizes from arbitrary CP coordinates. A two-stage ring reconstruction algorithm is proposed: (i) projecting the molecule in the xy plane and enforcing ring closure while preserving bond lengths, and (ii) redistributing angular distortions across the ring via constrained minimization to achieve chemically viable conformations. The approach is extended to rings with rigid (multiple) bonds through a rigorous ring-reduction scheme that lowers puckering dimensionality and incorporates local stiffness via adjustable parameters, allowing for straightforward recovery of the full structure. In addition, the positions of the substituents attached to the ring are deduced from invariant local references. To systematically explore the conformational space, we formulate a preconditioned sampling of CP amplitudes as a function of hyperspherical coordinates. In addition, the concept of basis conformations is examined to ensure the unambiguous identification of conformers. Applications to saturated and unsaturated rings with up to eight atoms at the ωB97X-D/def2-TZVPP level demonstrate accurate recovery and classification of known conformers, including correct symmetry multiplicities. Overall, this framework offers a robust and general route to generate high-quality starting geometries for subsequent electronic structure optimizations, while facilitating efficient exploration of puckering space
Thermodynamic conditions during growth determine the magnetic anisotropy in epitaxial thin-films of La0.7Sr0.3MnO3.
(IOP Publishing, 2016-07-14) Vila Fungueiriño, José Manuel; Bui, Cong Tinh; Rivas Murias, Beatriz; Winkler, E.; Milano, J.; Santiso, J.; Rivadulla Fernández, José Francisco; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
The suitability of a particular material for use in magnetic devices is determined by the process of magnetization reversal/relaxation, which in turn depends on the magnetic anisotropy. Therefore, designing new ways to control magnetic anisotropy in technologically important materials is highly desirable. Here we show that magnetic anisotropy of epitaxial thin-films of half-metallic ferromagnet La0.7Sr0.3MnO3 (LSMO) is determined by the proximity to thermodynamic equilibrium conditions during growth. We performed a series of x-ray diffraction and ferromagnetic resonance (FMR) experiments in two different sets of samples: the first corresponds to LSMO thin-films deposited under tensile strain on (0 0 1) SrTiO3 by pulsed laser deposition (PLD; far from thermodynamic equilibrium); the second were deposited by a slow chemical solution deposition (CSD) method, under quasi-equilibrium conditions. Thin films prepared by PLD show fourfold in-plane magnetic anisotropy, with an overimposed uniaxial term. However, the uniaxial anisotropy is completely suppressed in the CSD films. This change is due to a different rotation pattern of MnO6 octahedra to accommodate epitaxial strain, which depends not only on the amplitude of tensile stress imposed by the STO substrate, but also on the growth conditions. Our results demonstrate that the nature and magnitude of the magnetic anisotropy in LSMO can be tuned by the thermodynamic parameters during thin-film deposition
Tunnel conduction in epitaxial bilayers of ferromagnetic LaCoO3/La2/3Sr1/3MnO3 deposited by a chemical solution method
(American Chemical Society, 2014-11) Lucas, Irene; Vila Fungueiriño, José Manuel; Jiménez-Cavero, Pilar; Rivas Murias, Beatriz; Magén, César; Morellón, Luis; Rivadulla Fernández, José Francisco; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
We report magnetic and electronic transport measurements across epitaxial bilayers of ferromagnetic insulator LaCoO3 and half-metallic ferromagnet La2/3Sr1/3MnO3 (LCO/LSMO: 3.5 nm/20 nm) fabricated by a chemical solution method. The I–V curves at room temperature and 4K measured with conducting atomic force microscopy (CAFM) on well-defined patterned areas exhibit the typical features of a tunneling process. The curves have been fitted to the Simmons model to determine the height (φ) and width (s) of the insulating LCO barrier. The results yield φ = 0.40 ± 0.05 eV (0.50 ± 0.01 eV) at room temperature (4K) and s = 3 nm, in good agreement with the structural analysis. Our results demonstrate that this chemical method is able to produce epitaxial heterostructures with the quality required for this type of fundamental studies and applications.
Interface magnetic coupling in epitaxial bilayers of La0.92MnO3/ LaCoO3 prepared by polymer-assisted deposition
(American Chemical Society, 2014-01) Vila Fungueiriño, José Manuel; Rivas Murias, Beatriz; Rodríguez-González, Benito; Rivadulla Fernández, José Francisco; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
We report the synthesis of epitaxial bilayers of ultrathin La0.92MnO3/LaCoO3 (LMO/LCO) on SrTiO3 (STO) by polymer solution deposition. We have achieved an excellent control over the thickness (from ∼4 to ∼20 nm) and roughness of the films, which allows the fabrication of the sharp interfaces required for their functionality. We suggest that the large increase in the coercive field observed in the bilayer with respect to isolated films of LMO or LCO is due to a strong ferromagnetic Mn–O–Co superexchange interaction at the interface. Our results demonstrate that abrupt interfaces can be obtained in epitaxial multilayers by a simple and affordable chemical deposition technique, with the quality required for fundamental studies or highly demanding applications.
Room temperature ferromagnetism in thin films of LaMnO3 deposited by a chemical method over large areas
(American Chemical Society, 2015-02-10) Vila Fungueiriño, José Manuel; Rivas Murias, Beatriz; Rodríguez González, Benito; Txoperena, Oihana; Ciudad, D.; Hueso, Luis E.; Lazzari, Massimo; Rivadulla Fernández, José Francisco; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
Hole-doping into the Mott insulator LaMnO3 results in a very rich magneto-electric phase diagram, including colossal magnetoresistance and different types of charge and orbital ordering. On the other hand, LaMnO3 presents an important catalytic activity for oxygen reduction, which is fundamental for increasing the efficiency of solid-oxide fuel cells and other energy-conversion devices. In this work, we report the chemical solution (water-based) synthesis of high-quality epitaxial thin films of LaMnO3, free of defects at square-centimeter scales, and compatible with standard microfabrication techniques. The films show a robust ferromagnetic moment and large magnetoresistance at room temperature. Through a comparison with films grown by pulsed laser deposition, we show that the quasi-equilibrium growth conditions characteristic of this chemical process can be exploited to tune new functionalities of the material
Strong interfacial magnetic coupling in epitaxial bilayers of LaCoO3/LaMnO3 prepared by chemical solution deposition
(Elsevier, 2014-02) Vila Fungueiriño, José Manuel; Rivas Murias, Beatriz; Rivadulla Fernández, José Francisco; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS); Universidade de Santiago de Compostela. Departamento de Química Física
We report the synthesis of high quality epitaxial bilayers of LaMnO3/LaCoO3 (LCO/LMO) on (001) LaAlO3, by spin-coating of a polymeric aqueous solutions. The bilayer shows a very large increase of the magnetization coercive field (≈ 3000%) with respect to the isolated LMO or LCO films. We suggest that the origin of this effect is a strong Mn4 +–O–Co2 + exchange interaction at the interface. Our results demonstrate that a simple chemical method is able to produce high quality epitaxial heterostructures in which interfacial effects can modify substantially the properties of the individual layers
Crystal engineering and ferroelectricity at the nanoscale in epitaxial 1D manganese oxide on silicon
(Royal Society of Chemistry, 2021) Gomez, Andrés; Vila Fungueiriño, José Manuel; Jolly, Claire; Garcia-Bermejo, Ricardo; Oró-Solé, Judith; Ferain, Etienne; Mestres, Narcís; Magén, César; Gazquez, Jaume; Rodriguez-Carvajal, Juan; Carretero-Genevrier, Adrián; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS)
Ferroelectric oxides have attracted much attention due to their wide range of applications, particularly in electronic devices such as nonvolatile memories and tunnel junctions. As a result, the monolithic integration of these materials into silicon technology and their nanostructuration to develop alternative cost-effective processes are among the central points in the current technology. In this work, we used a chemical route to obtain nanowire thin films of a novel Sr1+δMn8O16 (SMO) hollandite-type manganese oxide on silicon. Scanning transmission electron microscopy combined with crystallographic computing reveals a crystal structure comprising hollandite and pyrolusite units sharing the edges of their MnO6 octahedra, resulting in three types of tunnels arranged along the c axis, where the ordering of the Sr atoms produces natural symmetry breaking. The novel structure gives rise to ferroelectricity and piezoelectricity, as revealed by local direct piezoelectric force microscopy measurements, which confirmed the ferroelectric nature of the SMO nanowire thin films at room temperature and showed a piezoelectric coefficient d33 value of 22 ± 6 pC N−1. Moreover, we proved that flexible vertical SMO nanowires can be harvested providing an electrical output energy through the piezoelectric effect, showing excellent deformability and high interface recombination. This work indicates the possibility of engineering the integration of 1D manganese oxides on silicon, a step which precedes the production of microelectronic devices.
Synthesis and magnetic properties of manganite thin films on Si by polymer assisted (PAD) and pulsed laser deposition (PLD)
(Springer Nature, 2012-06-01) Vila Fungueiriño, José Manuel; Rivas Murias, Beatriz; Rivadulla Fernández, José Francisco; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS); Universidade de Santiago de Compostela. Departamento de Química Física
We report the synthesis of polycrystalline films of La1-xCaxMnO3 in Si (111) by Polymer Assisted Deposition (PAD). An aqueous solution polyethyleneimine (PEI) and different metal ions stabilized with EDTA, was spin coated on hydrophilized Si substrates and subsequently annealed under different atmospheres. Homogeneous, dense polycrystalline films are obtained at optimized conditions of 950 °C under flowing O2. The morphology and magnetic properties of the samples are compared with films obtained by Pulsed Laser Deposition.
Strain-induced ferromagnetism and magnetoresistance in epitaxial thin films of LaCoO 3 prepared by polymer-assisted deposition
(ACS Publications, 2013) Rivadulla Fernández, José Francisco; Bi, Zhenxing; Bauer, Eve; Rivas Murias, Beatriz; Vila Fungueiriño, José Manuel; Jia, Quanxi; Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS); Universidade de Santiago de Compostela. Departamento de Química Física
High quality epitaxial thin films of LaCoO3 on SrTiO3 have been prepared by spin-coating of a metal/polymeric aqueous solution. The films (≈ 17 nm) are homogeneous and smooth over large areas. The characteristic low-spin (LS) state is replaced by a higher spin configuration of Co(III), due to strain-induced distortions of the CoO6 octahedra, introducing a ferromagnetic interaction and negative magnetoresistance below TC = 85 K. This simple chemical method produces the high-quality films required for either fundamental studies or applications, similar to physical deposition techniques

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