Erratum: Interlaboratory study on SbS interplay between structure, dielectric function, and amorphous-to-crystalline phase change for photonics.

[This corrects the article DOI: 10.1016/j.isci.

Liquid-Crystal-Like Dynamic Transition in Ferroelectric-Dielectric Superlattices.

Nanostructured ferroelectrics display exotic multidomain configurations resulting from the electrostatic and elastic boundary conditions they are subject to. While the ferroelectric domains appear frozen in experimental images, atomistic second-principles studies suggest that they may become spontaneously mobile upon heating, with the polar order melting in a liquidlike fashion. Here, we run molecular dynamics simulations of model systems (PbTiO_{3}/SrTiO_{3} superlattices) to study the unique features of this transformation.

Interlayer Coupling Controlled Ordering and Phases in Polar Vortex Superlattices.

The recent discovery of polar topological structures has opened the door for exciting physics and emergent properties. There is, however, little methodology to engineer stability and ordering in these systems, properties of interest for engineering emergent functionalities. Notably, when the surface area is extended to arbitrary thicknesses, the topological polar texture becomes unstable.

Pure Chiral Polar Vortex Phase in PbTiO/SrTiO Superlattices with Tunable Circular Dichroism.

Nontrivial polarization textures have been demonstrated in ferroelectric/dielectric superlattices, where the electrostatic, elastic, and different gradient energies compete in a delicate balance. When PbTiO/SrTiO superlattices are grown on DyScO, the coexistence of ferroelectric domains and vortex structure is observed for = 12-20 unit cells. Here, we report an approach to achieve single-phase vortex structures in superlattices by controlling the epitaxial strain using SrAlGaTaO substrates.

Emergent Ferroelectric Switching Behavior from Polar Vortex Lattice.

Topologically protected polar textures have provided a rich playground for the exploration of novel, emergent phenomena. Recent discoveries indicate that ferroelectric vortices and skyrmions not only host properties markedly different from traditional ferroelectrics, but also that these properties can be harnessed for unique memory devices. Using a combination of capacitor-based capacitance measurements and computational models, it is demonstrated that polar vortices in dielectric-ferroelectric-dielectric trilayers exhibit classical ferroelectric bi-stability together with the existence of low-field metastable polarization states.

Emergent chirality in a polar meron to skyrmion phase transition.

Polar skyrmions are predicted to emerge from the interplay of elastic, electrostatic and gradient energies, in contrast to the key role of the anti-symmetric Dzyalozhinskii-Moriya interaction in magnetic skyrmions. Here, we explore the reversible transition from a skyrmion state (topological charge of -1) to a two-dimensional, tetratic lattice of merons (with topological charge of -1/2) upon varying the temperature and elastic boundary conditions in [(PbTiO)/(SrTiO)] membranes. This topological phase transition is accompanied by a change in chirality, from zero-net chirality (in meronic phase) to net-handedness (in skyrmionic phase).

Interlaboratory study on SbS interplay between structure, dielectric function, and amorphous-to-crystalline phase change for photonics.

Antimony sulfide, SbS, is interesting as the phase-change material for applications requiring high transmission from the visible to telecom wavelengths, with its band gap tunable from 2.2 to 1.6 eV, depending on the amorphous and crystalline phase.

Inherent Spin-Polarization Coupling in a Magnetoelectric Vortex.

Solid-state materials are currently being explored as a platform for the manipulation of spins for spintronics and quantum information science. More broadly, a wide spectrum of ferroelectric materials, spanning from inorganic oxides to polymeric systems such as PVDF, present a different approach to explore quantum phenomena in which the spins are set and manipulated with electric fields. Using dilute Fe-doped ferroelectric PbTiO-SrTiO superlattices as a model system, we demonstrate intrinsic spin-polarization control of spin directionality in complex ferroelectric vortices and skyrmions.

Electric field control of chirality.

Polar textures have attracted substantial attention in recent years as a promising analog to spin-based textures in ferromagnets. Here, using optical second-harmonic generation–based circular dichroism, we demonstrate deterministic and reversible control of chirality over mesoscale regions in ferroelectric vortices using an applied electric field. The microscopic origins of the chirality, the pathway during the switching, and the mechanism for electric field control are described theoretically via phase-field modeling and second-principles simulations, and experimentally by examination of the microscopic response of the vortices under an applied field.

Atomic scale crystal field mapping of polar vortices in oxide superlattices.

Polar vortices in oxide superlattices exhibit complex polarization topologies. Using a combination of electron energy loss near-edge structure analysis, crystal field multiplet theory, and first-principles calculations, we probe the electronic structure within such polar vortices in [(PbTiO)/(SrTiO)] superlattices at the atomic scale. The peaks in Ti [Formula: see text]-edge spectra shift systematically depending on the position of the Ti cations within the vortices i.

Vortex Domain Walls in Ferroelectrics.

Controlling the domain formation in ferroelectric materials at the nanoscale is a fertile ground to explore emergent phenomena and their technological prospects. For example, charged ferroelectric domain walls in BiFeO and ErMnO exhibit significantly enhanced conductivity which could serve as the foundation for next-generation circuits (Estévez and Laurson, , , 054407). Here, we describe a concept in which polar vortices perform the same role as a ferroelectric domain wall in classical domain structures with the key difference being that the polar vortices can accommodate charged (.

Siesta: Recent developments and applications.

A review of the present status, recent enhancements, and applicability of the Siesta program is presented. Since its debut in the mid-1990s, Siesta's flexibility, efficiency, and free distribution have given advanced materials simulation capabilities to many groups worldwide. The core methodological scheme of Siesta combines finite-support pseudo-atomic orbitals as basis sets, norm-conserving pseudopotentials, and a real-space grid for the representation of charge density and potentials and the computation of their associated matrix elements.

Author Correction: Spatially resolved steady-state negative capacitance.

In this Letter, the first name of author Bhagwati Prasad was misspelled Bhagawati. This error has been corrected online.

Theoretical guidelines to create and tune electric skyrmion bubbles.

Researchers have long wondered whether ferroelectrics may present topological textures akin to magnetic skyrmions and chiral bubbles, the results being modest thus far. An electric equivalent of a typical magnetic skyrmion would rely on a counterpart of the Dzyaloshinskii-Moriya interaction and seems all but impossible; further, the exotic ferroelectric orders reported to date rely on specific composites and superlattices, limiting their generality and properties. Here, we propose an original approach to write topological textures in simple ferroelectrics in a customary manner.

Spatially resolved steady-state negative capacitance.

Negative capacitance is a newly discovered state of ferroelectric materials that holds promise for electronics applications by exploiting a region of thermodynamic space that is normally not accessible. Although existing reports of negative capacitance substantiate the importance of this phenomenon, they have focused on its macroscale manifestation. These manifestations demonstrate possible uses of steady-state negative capacitance-for example, enhancing the capacitance of a ferroelectric-dielectric heterostructure or improving the subthreshold swing of a transistor.

Emergent chirality in the electric polarization texture of titanate superlattices.

Chirality is a geometrical property by which an object is not superimposable onto its mirror image, thereby imparting a handedness. Chirality determines many important properties in nature-from the strength of the weak interactions according to the electroweak theory in particle physics to the binding of enzymes with naturally occurring amino acids or sugars, reactions that are fundamental for life. In condensed matter physics, the prediction of topologically protected magnetic skyrmions and related spin textures in chiral magnets has stimulated significant research.

Giant Optical Polarization Rotation Induced by Spin-Orbit Coupling in Polarons.

We have uncovered a giant gyrotropic magneto-optical response for doped ferromagnetic manganite La_{2/3}Ca_{1/3}MnO_{3} around the near room-temperature paramagnetic-to-ferromagnetic transition. At odds with current wisdom, where this response is usually assumed to be fundamentally fixed by the electronic band structure, we point to the presence of small polarons as the driving force for this unexpected phenomenon. We explain the observed properties by the intricate interplay of mobility, Jahn-Teller effect, and spin-orbit coupling of small polarons.

Dynamically slow solid-to-solid phase transition induced by thermal treatment of DimimFeCl4 magnetic ionic liquid.

The results reported here represent the first direct experimental observations supporting the existence of a solid-to-solid phase transition induced by thermal treatment in magnetic ionic liquids (MILs). The phase transitions of the solid phases of 1,3-dimethylimidazolium tetrachloroferrate, DimimFeCl4, are closely related to its thermal history. Two series of solid-to-solid phase transitions can be described in this MIL: (i) from room temperature (RT) phase II [space group (s.

Anion-π and halide-halide nonbonding interactions in a new ionic liquid based on imidazolium cation with three-dimensional magnetic ordering in the solid state.

We present the first magnetic phase of an ionic liquid with anion-π interactions, which displays a three-dimensional (3D) magnetic ordering below the Néel temperature, TN = 7.7 K. In this material, called Dimim[FeBr4], an exhaustive and systematic study involving structural and physical characterization (synchrotron X-ray, neutron powder diffraction, direct current and alternating current magnetic susceptibility, magnetization, heat capacity, Raman and Mössbauer measurements) as well as first-principles analysis (density functional theory (DFT) simulation) was performed.

A magnetic ionic liquid based on tetrachloroferrate exhibits three-dimensional magnetic ordering: a combined experimental and theoretical study of the magnetic interaction mechanism.

A new magnetic ionic liquid (MIL) with 3D antiferromagnetic ordering has been synthetized and characterized. The information obtained from magnetic characterization was supplemented by analysis of DFT calculations and the magneto-structural correlations. The result gives no evidence for direct iron-iron interactions, corroborating that the 3D magnetic ordering in MILs takes place via super-exchange coupling containing two diamagnetic atoms intermediaries.