arXiv subjects

Araceli Gutiérrez-Llorente

Publications and source records attributed to Araceli Gutiérrez-Llorente.

5 recordsLinked to original sources

arXiv2026

Complex polar superstructure controlled thermal conductivity in ferroelectric PbTiO3/SrTiO3 superlattices

Integrating epitaxial thin films of ferroelectric PbTiO3 and paraelectric SrTiO3 into artificially layered periodic superlattices provides a unique platform for tuning strain, depolarization, and interfacial/surface energies, thereby accessing a rich phase diagram of topological polar structures (skyrmions, vortices, merons, or sinusoidal waves) and superstructures (polar supercrystals). Here we show that the 3D arrangement of polar vortices in a supercrystal suppresses thermal conductivity (k) of PTO/STO superlattices (SLs). The temperature dependence of k reflects the evolution of the polar superstructure, as determined by X-ray diffraction and transmission electron microscopy. The comparison with other SLs suggests that the 3D arrangement is crucial for controlling thermal conductivity beyond the usual interfacial scattering. Moreover, we observed an unexpected reduction in thermal conductivity with increasing superlattice thickness, a phenomenon reminiscent of phonon-wave Anderson localization. Our results show that complex polar superstructures can be useful active elements for modulating heat transport in technologies where control over heat dissipation is critical.

cond-mat.mtrl-sci↗

arXiv2026

Higher-order topological bound states in the continuum in a topoelectrical lattice with long-range coupling

Linear electric circuits composed of inductors and capacitors can serve as analogues of tight-binding models that describe the electronic band structure of materials. This mapping provides a versatile approach for exploring topological phenomena within engineered electrical lattices. In this work, the two-dimensional Su-Schrieffer-Heeger model is examined through electric circuit analogues to study the interplay between higher-order topology, bound states in the continuum, and disorder. Building upon this model, the effect of introducing next-nearest-neighbour interactions that preserve chiral and spatial symmetries of the system is analyzed. The results reveal that even without Hamiltonian separability, corner-localized bound states in the continuum remain protected by symmetry in the long-range coupled lattice. This robustness highlights the potential of circuit-based platforms for probing advanced topological phenomena in a highly controllable setting.

cond-mat.other↗

arXiv2025

Epitaxial thin films of pyrochlore iridates: a forward looking approach

Topological quantum materials that show strongly correlated electrons as well as topological order, for which spin-orbit coupling is a key ingredient, exhibit novel states of matter. One such example is the family of pyrochlore iridates, featuring strong spin-orbital coupling, strong electron interactions as well as geometric frustration, making them an ideal platform to study novel topological phases. High-quality epitaxial pyrochlore iridate films, although challenging to produce, provide a pathway to explore unconventional behaviours and unravel the intrinsic properties of these largely unexplored materials. Additionally, designing interfaces with specific properties is crucial to create multilayered devices that can achieve significant technological breakthroughs using topological states of these materials. This article reviews experimental work on epitaxial pyrochlore iridate thin films, discussing evidence of topological phases found in them. Future research directions are outlined, which include exploring the rich tunability offered by chemical doping, especially when combined with the design of epitaxial heterostructures.

cond-mat.str-el↗

arXiv2024

Unraveling p-type and n-type interfaces in Superconducting Infinite-Layer Nickelate thin films

After decades of research, superconductivity was finally found in nickel-based analogs of superconducting cuprates, with infinite-layer (IL) structure. These results are so far restricted to thin films in the case of IL-nickelates. Therefore, the nature of the interface with the substrate, and how it couples with the thin film properties is still an open question. Here, using scanning transmission electron microscopy (STEM)- electron energy loss spectroscopy (EELS) and four-dimensional (4D)-STEM, a novel chemically sharp p-type interface is observed in a series of superconducting IL-praseodymium nickelate samples, and a comparative study is carried out with the previously reported n-type interface obtained in other samples. Both interfaces have strong differences, with the p-type interface being highly polar. In combination with ab-initio calculations, we find that the influence of the interface on the electronic structure is local, and does not extend beyond 2-3 unit cells into the thin film. This decouples the direct influence of the interface in driving the superconductivity, and indicates that the IL-nickelate thin films do not have a universal interface model. Insights into the spatial hole-distribution in SC samples, provided by monochromated EELS and total reflection-hard x-ray photoemission spectroscopy, suggest that this particular distribution might be directly influencing superconductivity.

cond-mat.supr-con↗

arXiv2024

Towards reliable synthesis of superconducting infinite layer nickelate thin films by topochemical reduction

Infinite layer nickelates provide a new route beyond copper oxides to address outstanding questions in the field of unconventional superconductivity. However, their synthesis poses considerable challenges, largely hindering experimental research on this new class of oxide superconductors. That synthesis is achieved in a two-step process that yields the most thermodynamically stable perovskite phase first, then the infinite-layer phase by topotactic reduction, the quality of the starting phase playing a crucial role. Here, we report on reliable synthesis of superconducting infinite-layer nickelate films after successive topochemical reductions of a parent perovskite phase with nearly optimal stoichiometry. Careful analysis of the transport properties of the incompletely reduced films reveals an improvement of the strange metal behaviour of their normal state resistivity over subsequent topochemical reductions, offering insight into the reduction process.

cond-mat.supr-con↗