Low Polarization Research Articles

La judicialización de la política y el control constitucional en modelos híbridos restringidos: el activismo judicial por “defecto” de ParaguayThe judicialization of politics and judicial review in restricted hybrid models: judicial activism by “default” in Paraguay

Abstract Does the institutional design of constitutional review affect the judicialization of politics and judicial behavior? Traditionally, political factors and the personal characteristics of judges are considered the main explanations for judicial behavior, often overlooking the role of institutional design. This article examines the “restricted hybrid” model of constitutional review in Paraguay, a country with low political polarization due to party hegemony, yet marked by judicial activism. The analysis of the Constitutional Chamber between 1995 and 2015 reveals that the restricted hybrid design influences judges voting behavior, suggesting that judicial activism is not necessarily a deliberate strategy but an unintended consequence of the institutional design. In contexts of low polarization and restricted constitutional review, like in Paraguay, judges have shown deference to strong presidents but not to strong congresses.

A Strategy of Enhancing Polarization to Achieve Excellent Energy Storage Performance in Simple Bi0.5K0.5TiO3‐Based Relaxors

AbstractDielectric energy storage capacitors are indispensable components in advanced electronic and electrical systems. Excellent performance requires the dielectric materials possessing low residual polarization (Pr), high breakdown strength (Eb), and large maximum polarization (Pm). The first two parameters can be typically achieved through chemical regulation, while the Pmax is closely related to the matrix. Theoretical calculations demonstrate that a strong coupling of A‐O bonds and a large lattice can enhance polarization, thus identifying the prototype Bi0.5K0.5TiO3 as a favorable matrix. Here, ultrahigh energy density of 16.5 J/cm3 and high efficiency of 88.2 % are achieved in 0.76Bi0.5K0.5TiO3‐0.24Ca0.5Sr0.5HfO3 binary system. This system exhibits the highest comprehensive performance among all reported Bi0.5K0.5TiO3‐based ceramics. The large perovskite framework facilitated by the large ionic radius of K+ enhances the local polarity of Bi−O and Ca−O, resulting in a large Pm of 57.4 μC/cm2 under an ultrahigh Eb of 82 kV/mm. The highly disordered local polar clusters at the nanoscale lead to negligible Pr and high η. This work not only provides a unique design concept to enhance the comprehensive energy storage performance from the perspective of local structure, but also offers insight into the origin of high performance.

High Heat Resistance and Low Dielectric o‐Cresol Formaldehyde Epoxy Resin Solder Resist Containing Photocurable Small Molecular Compound Based on 3,4‐Epoxycyclohexylmethyl Methacrylate

ABSTRACTHigh heat resistance and low dielectric constant are the development trend for PCB ink. Generally, higher crosslinking density and rigid molecular structure are beneficial for improving the heat resistance, and low polarity molecules and larger three‐dimensional structure are helpful for reducing dielectric constant. In this work, based on the photocurable small molecular epoxy compound 3,4‐epoxycyclohexylmethyl methacrylate (TTA15), we successively grafted it with acrylic acid (AA) and 1,2,5,6‐tetrahydrophthalic anhydride (THPA), named 15AT. After modification with AA and THPA, two unsaturated double bonds were introduced. In 15AT, containing three double bonds and a cyclohexyl ring, mixed as an auxiliary resin into the main resin EPT‐001 (industrialized o‐cresol formaldehyde epoxy resin grafted with AA and THPA products), it is obviously possible to improve the heat resistance. According to the addition mass of 15AT in total resin, 0%, 5%, 10%, 15%, and 20% were named EAT, EAT15‐5, EAT15‐10, EAT15‐15, and EAT15‐20, respectively. The results show that the introduction of 15AT increases the Tg value by up to 37.1°C and also has the lowest dielectric constant (2.45), which is 0.29 lower than the original resin EAT, thereby offering a new approach to improving the properties of PCB ink.

Innovative Approach to Achieving Polarization Dependent Highly Directional Nanolasers Through Propagating States in Diverse Plasmonic Lattices.

With their extremely small mode volumes, excellent field enhancement, and low radiative loss, metallic nanoparticle arrays supporting plasmonic lattice resonances have emerged as a potential design for on-chip plasmonic lasers. Due to the similarities between photonic crystals and plasmonic lattices in terms of structural features and energy band structure, the properties of plasmonic lattice-based nanolasers, including low threshold, lasing wavelength, coherence, directionality, and polarization, can be designed using band structure computations. Here 2D plasmonic lattices of Al nanocone arrays (NCAs) are presented, supporting narrow linewidth resonances that provide optical feedback for the stimulated emission process of optically pumped Rhodamine 6G (R6G). Remarkably, highly directional nanoscale lasing with polarization dependence at red-light wavelengths is presented by the artificially predesigned plasmonic band structure at the propagating state with different lattice symmetries and enables effective coupling with quantum emitters at various wavelengths. Furthermore, the lasing dynamics in these structures are also investigated, employing a dynamic semi-quantum approach that considers both stimulated and spontaneous emission. These findings broaden the lasing characteristics diversity in plasmonic nanoparticle arrays and provide a simple framework for presenting promising prospects for the management and operation of on-chip nanoscale laser sources.

Experimental unified pH scale in 1,2-dichloroethane.

Experimental potentiometric unified pH (pHabs) scale is presented in 1,2-dichloroethane (1,2-DCE). The scale was compiled using differential potentiometric measurements, carried out by pair-wise comparisons between solutions. Aqueous standard buffer solutions were used as anchor points, so that the obtained pH values are linked to (i.e., are traceable to) the conventional aqueous pH scale and are expressed as values. They are directly comparable to pH values in water in terms of the chemical potential of the solvated proton. The "ladder" approach was used for data analysis and values were assigned to 19 solutions in 1,2-DCE, leading to a scale spanning from -2.9 to 11.0. This is the first time that successful potentiometric measurements have been carried out in a solvent of as low polarity as 1,2-DCE. The whole set of measurements, comprising a total of 85 ΔpHabs values, has a consistency standard deviation of 0.17 pH units. This is higher compared to the consistency standard deviations reported in the literature for similar measurements in other solvents and reflects the experimental difficulties with potentiometric measurements in a low-polarity solvent. This result means that potentiometric measurement of values is possible in low-polarity solvents, and it is thus expected that potentiometric measurement is possible in most organic solvents, opening the possibility of experimentally connecting many solvents into the unified scale.

A Strategy of Enhancing Polarization to Achieve Excellent Energy Storage Performance in Simple Bi0.5K0.5TiO3-Based Relaxors.

Dielectric energy storage capacitors are indispensable components in advanced electronic and electrical systems. Excellent performance requires the dielectric materials possessing low residual polarization (Pr), high breakdown strength (Eb), and large maximum polarization (Pm). The first two parameters can be typically achieved through chemical regulation, while the Pmax is closely related to the matrix. Theoretical calculations demonstrate that a strong coupling of A-O bonds and a large lattice can enhance polarization, thus identifying the prototype Bi0.5K0.5TiO3 as a favorable matrix. Here, ultrahigh energy density of 16.5 J/cm3 and high efficiency of 88.2% are achieved in 0.76Bi0.5K0.5TiO3-0.24Ca0.5Sr0.5HfO3 binary system. This system exhibits the highest comprehensive performance among all reported Bi0.5K0.5TiO3-based ceramics. The large perovskite framework facilitated by the large ionic radius of K+ enhances the local polarity of Bi-O and Ca-O, resulting in a large Pm of 57.4 µC/cm2 under an ultrahigh Eb of 82 kV/mm. The highly disordered local polar clusters at the nanoscale lead to negligible Pr and high η. This work not only provides a unique design concept to enhance the comprehensive energy storage performance from the perspective of local structure, but also offers insight into the origin of high performance.

Self-Adaptive Polarized Photoresponse in Organic Single-Crystal Phototransistors for Bionic Night-Time Polarization Perception.

The emerging semiconductor micro/nanocrystals with intrinsic anisotropy have provided new perspectives for low-cost and simplified polarimetry. However, the low polarization sensitivity of state-of-the-art polarimeters based on anisotropic semiconductors under weak and partially polarized light severely hinders their practical application in complex dim environments. Here, a photo-adaptive polarization-sensitive organic phototransistor (POL-OPT) is demonstrated for bionic weak-light polarization perception. The combination of highly anisotropic organic crystals with charge-storage accumulative effect enables a self-adaptive polarized photoresponse of the phototransistor to imitate the bionic scotopic adaptation process. Consequently, an ultrahigh dichroic ratio (DR) of over 105 is achieved through time accumulation under an ultraweak light intensity of 200 nW cm-2, which is among the highest in polarization-sensitive photodetectors. Furthermore, POL-OPT array is constructed for effective polarization perception in an artificial moonlit environment with a low degree of linear polarization (DoLP) down to 0.26, reaching the detection threshold of night-active dung beetles. This study offers a new opportunity for the development of new-generation high-performance polarimeters for polarization imaging, bionic navigation, and artificial visual systems.

Giant Capacitive Energy‐Storage in BaTiO3‐Based Fine‐Grained Relaxors via Local Polarization Enhancement

AbstractPb‐free dielectric energy storage capacitors are core components in advanced pulse‐power electronic systems and devices. However, the relatively low energy density (Wrec) for the industrial pillar BaTiO3 (BT)‐based capacitors remains a significant obstacle for their cutting‐edge applications, due to their low intrinsic polarization and breakdown strength (EB). Herein, through chemical composition and local structure design, a giant Wrec of 15.1 J cm−3 along with a high efficiency (η) of 85% is demonstrated in a BT‐based relaxor bulk ceramic. This is achieved by introducing rare A‐site polarization enhancement substitution (Bi0.5Na0.5)2+ ions in combination with B‐site fastest relaxation alternative (Zn1/3Nb2/3)4+ ions to enhance local polarization and refine grain structure. Atomic‐level local structure analysis has revealed that the diversified atomic polar displacement vectors, characterized by largely extended magnitude and heterogeneous directions, assemble into highly polarizable clusters at several unit‐cells scale. Consequently, it exerts a large polarization difference (ΔP) of 49 µC cm−2 and a high EB of 90 kV mm−1. Moreover, a giant power density (677 MW cm−3), high discharge energy density (3.9 J cm−3), and excellent stability are achieved. This study overcomes the current Wrec bottleneck of ≈10 J cm−3 in BT‐based bulk ceramics, presenting an approach to optimize the energy storage performance of Pb‐free relaxors.

Highly Nucleophilic Pyridinamide Anions in Apolar Organic Solvents due to Asymmetric Ion Pair Association.

Free ions in organic solvents of low polarity would be valuable tools for the activation of low-reactivity substrates. However, the formation of unreactive ion pairs at concentrations relevant for synthesis has prevented the success of this concept so far. On the example of highly nucleophilic pyridinamide phosphonium salts in dichloromethane, we show that asymmetric aggregation offers a solution to this general problem. A combination of conductivity, diffusion-ordered NMR (DOSY), and kinetic measurements utilizing a refined ionic strength-controlled benzhydrylium ion methodology enables unique insight into the aggregation/association state of the ions and the nucleophilicity of the involved anions. This approach reveals that pyridinamide tetraphenylphosphonium salts aggregate in dichloromethane solution asymmetrically to form sandwich-type cations and anions together with their free counterions. The nucleophilicity of free pyridinamide ions exceeds that of the neutral reference nucleophile 9-azajulolidine (TCAP) by up to 2 orders of magnitude. Based on these results, we suggest that asymmetric aggregation in organic solvents of low polarity might be a general pathway to boost the reactivity of anionic nucleophiles.

Metallic Sliding Ferroelectricity in Trilayer Penta‐NiN2

AbstractThe experimental observation of metallic ferroelectricity has challenged the traditional understanding in recent years, as metallicity and ferroelectricity are historically considered mutually exclusive. This breakthrough has sparked significant interest in this field. However, the coexistence of metallicity and sliding ferroelectricity in 2D pentagonal materials has not been reported yet. Here, this is theoretically studied that the sliding ferroelectricity in metallic trilayer penta‐NiN2. By scanning the configuration space of stacking patterns, a pair of polarized configurations is identified with strong out‐of‐plane ferroelectric polarization of ± 5.39 × 10−13 C m−1 and a low polarization switching barrier of 14.33 meV/atom together with a non‐polarized configuration as the intermediate state for the ferroelectric transition. It is also found that there are substantial changes in the second harmonic generation of the stable configurations that would facilitate experimental observation. This work demonstrates the potential of pentagonal sheets as promising metallic sliding ferroelectrics, which would significantly expand the family of sliding ferroelectric materials.

Piezoelectric Vitamin-Based Self-Assemblies for Energy Generation.

Structural diversity of biomolecules leads to various supramolecular organizations and asymmetric architectures of self-assemblies with significant piezoelectric response. However, the piezoelectricity of biomolecular self-assemblies has not been fully explored and the relationship between supramolecular structures and piezoelectricity remains poorly understood, which hinders the development of piezoelectric biomaterials. Herein, for the first time, the piezoelectricity of vitamin-based self-assemblies for power generation is systematically explored. X-ray diffraction studies revealed that vitamin molecules can self-assemble into different supramolecular structures, which exhibited tunable piezoelectric coefficients ranging from 3.8 to 42.8 pCN-1 by density functional theory (DFT) calculations. Notably, vitamin B7 D-biotin (D-BIO) self-assemblies exhibited superior piezoelectricity due to low crystal symmetry and high polarization of supramolecular arrangements. The D-BIO assemblies-based piezoelectric nanogenerator (PENG) produced output voltages of ≈0.8 V under a mechanical force of 47 N, showing high mechanical durability after 5400 pressing-releasing cycles and high stability of at least three months. The PENG-based wearable sensor successfully detected bending motions of human limbs. Furthermore, the PENG-based insole converted biomechanical energy into stable electrical energy upon foot movement, illuminating 12 light-emitting diodes (LEDs). This work fills knowledge gaps in piezoelectricity of vitamin-based self-assemblies, providing paradigms for realizing high-performance piezoelectric biomaterials through supramolecular engineering.

Linear Dielectric Polymers with Ferroelectric-Like Crystals for High-Temperature Capacitive Energy Storage.

Achieving optimal capacitive energy storage performance necessitates the integration of high energy storage density, typical of ferroelectric dielectrics, with the low polarization loss associated with linear dielectrics. However, combining these characteristics in a single dielectric material is challenging due to the inherent contradictions between the spontaneous polarization of ferroelectric dielectrics and the adaptability of linear dielectrics to changes in the electric field. To address this issue, a linear isotactic sulfonylated polynorbornene dielectric characterized by ferroelectric-like crystals has been developed. The sulfonyl dipoles in the ferroelectric-like crystals are oriented in the same direction, thereby enabling this polymer to exhibit a considerable dielectric constant (7.5) at room temperature. Notably, when the operating temperature surpasses the polymer's glass transition temperature (Tg ≈ 140 °C), its dielectric constant rises to 12 with just minor changes in the dissipation factor. At 150 °C, 90% efficiency of the discharge energy density reaches as high as 6.76 Jcm-1 under a low electric field of 320 MV m-1, which is ten times that of the state-of-the-art, high-temperature, capacitor-grade polyetherimide. The enhancement of high-temperature capacitive performance, achieved by utilizing the crystallinity of isotactic polymers to form a polar structure, presents a new perspective for the design of high-temperature dielectric polymers.

High-entropy assisted capacitive energy storage in relaxor ferroelectrics by chemical short-range order

Next-generation advanced high/pulsed power capacitors rely heavily on dielectric ceramics with high energy storage performance. Although high entropy relaxor ferroelectric exhibited enormous potential in functional materials, the chemical short-range order, which is a common phenomenon in high entropy alloys to modulate performances, have been paid less attention here. We design a chemical short-range order strategy to modulate polarization response under external electric field and achieve substantial enhancements of energy storage properties, i.e. an ultrahigh energy density of ~16.4 J/cm3 with markedly improved efficiency ~90% at an electric field of 85 kV/mm in Nb doped (Bi0.2Na0.2K0.2La0.2Sr0.2) TiO3 system. Atomic-scale scanning transmission electron microscopy observations show that Nb exhibits a chemical short-range order structure, with Nb enriched regions displaying ultrasmall polar nanoregions and more flexible polarization configurations, which is conducive to achieving high maximum polarization and low residual polarization. Moreover, refined grain size of ~0.25μm, suppressed oxygen vacancies and enhanced bandwidth contribute to a high breakdown field strength. These collective factors result in exceptionally high energy storage density and efficiency. This short-range order strategy is expected to enhance the functional performances in other high entropy relaxor ferroelectrics.

A DIY Bioreactor for in Situ Metabolic Tracking in 3D Cell Models via Hyperpolarized 13C NMR Spectroscopy.

Nuclear magnetic resonance (NMR) spectroscopy is a valuable diagnostic tool limited by low sensitivity due to low nuclear spin polarization. Hyperpolarization techniques, such as dissolution dynamic nuclear polarization, significantly enhance sensitivity, enabling real-time tracking of cellular metabolism. However, traditional high-field NMR systems and bioreactor platforms pose challenges, including the need for specialized equipment and fixed sample volumes. This study introduces a scalable, 3D-printed bioreactor platform compatible with low-field NMR spectrometers, designed to accommodate bioengineered 3D cell models. The bioreactor is fabricated using biocompatible materials and features a microfluidic system for media recirculation, ensuring optimal culture conditions during NMR acquisition and cell maintenance. We characterized the NMR compatibility of the bioreactor components and confirmed minimal signal distortion. The bioreactor's efficacy was validated using HeLa and HepG2 cells, demonstrating prolonged cell viability and enhanced metabolic activity in 3D cultures compared to 2D cultures. Hyperpolarized [1-13C] pyruvate experiments revealed distinct metabolic profiles for the two cell types, highlighting the bioreactor's ability to discern metabolic profiles among samples. Our results indicate that the bioreactor platform supports the maintenance and analysis of 3D cell models in NMR studies, offering a versatile and accessible tool for metabolic and biochemical research in tissue engineering. This platform bridges the gap between advanced cellular models and NMR spectroscopy, providing a robust framework for future applications in nonspecialized laboratories. The design files for the 3D printed components are shared within the text for easy download and customization, promoting their use and adaptation for further applications.

Spin injection and detection using perpendicularly magnetized Mn/Co bilayers grown on GaAs via all electrical methods

The electrical spin injection and detection in perpendicularly magnetized Mn/Co/n-GaAs junction was investigated using a non-local method. Clear non-local spin-valve signals and Hanle effect signals were observed at 77 K, providing direct evidence of the injection and detection of perpendicularly polarized spins through all electrical methods. The magnitude of the spin-valve signal was one order of magnitude smaller than that observed in a reference sample with an in-plane magnetized CoFe due to the low spin polarization of the ultrathin Mn/Co electrodes. It was found that the spin polarization at the interface between Mn/Co electrode and n+-GaAs had a relatively weak bias-current dependence in contrast to that at CoFe/n+-GaAs interface. The estimated spin lifetime of perpendicular spins injected from the Mn/Co bilayer into n-GaAs was approximately 1.9 ns at 77 K. This value is similar to that of in-plane spins injected from CoFe, indicating that the spin lifetime was not strongly dependent on the spin orientation in the bulk GaAs channel.

Amorphous/Crystalline Urchin-Like TiO2 SERS Platform for Selective Recognition and Efficient Identification of Glutathione.

Glutathione serves as a common biomarkers in tumor diagnosis and treatment. The levels of its intracellular concentration permit detailed investigation of the tumor microenvironment. However, low polarization and weak Raman scattering cross-section make direct and indirect Raman detection challenging. This study designs an amorphous-crystalline urchin-like TiO2 (AC-UL-TiO2) for the accurate identification of GSH and GSSG. By synergistically regulating the crystalline core and amorphous shell, the bandgap structure is optimized, thereby enhancing charge transfer efficiency. AC-UL-TiO2 demonstrates excellent SERS performance in detecting dye molecules with good selectivity for mixed analytes. The enhancement factor (EF) for R6G is 6.89 × 106, and the limit of detection (LOD) is 10-10M. A SERS-colorimetric dual-modality platform is developed based on the AC-UL-TiO2@DTNB system to accurately monitor GSH concentrations from 0 to 1000 µM, providing a robust dual-confirmation result. Importantly, combined with the principal component analysis method, the AC-UL-TiO2 SERS platform can directly distinguish GSH and GSSG molecules. Besides, direct SERS detection LOD for GSH and GSSG are 10-8M, which is 100 times higher than that of indirect detection. These findings indicate that AC-UL-TiO2 holds potential for biomarkers trace detection in tumor microenvironments.

Synthesis of a photocrosslinkable polyimide with a chalcone side chain and its properties as a coating material for a secondary battery separator

A carboxyl-containing polyimide (PI) was synthesized with a flexible main chain. Then, a polymer reaction was conducted to introduce a chalcone side chain. The polymer reaction occurred stoichiometrically, and a high yield of the resulting photocrosslinkable polyimide (PI-Ch) polymer was obtained (91 %) along with a high molecular weight of 9.4 × 104 g/mol. The PI-Ch had a density of 1.15 g/cm3, a fractional free volume of 0.20, and a solubility parameter of 18.8 MPa1/2. Due to its low polarity, the PI-Ch was very soluble in a moderately polar, low-boiling-point solvent of THF. Moreover, the temperature required to promote 5 % weight loss was quite high at 383 °C, while the glass transition temperature was relatively low at 146 °C. The THF solution was considered to be optimal for the dip-coating method and was applied to PE separator coating. The ATR-mode FTIR analysis of the separator coated with a 1 wt% PI-Ch solution showed that the PI-Ch was coated extensively on the surface of the PE separator. Further, the photodimerization reaction of the chalcone side chain via UV irradiation was successful. The PE separator had a thermal shrinkage of 46 % before coating, which decreased to 29 % after coating and UV treatment. When coated with a 3 wt% PI-Ch solution, some of the pores in the separator were blocked, while the air permeability and average pore size also decreased. All the pores appeared blocked after coating with the 5 wt% PI-Ch solution.

Electrochemical-thermal-mechanical overcharge model on a scale of particle for lithium-ion batteries

During overcharging of lithium-ion batteries, lithium plating can occur on the anode surface when the maximum lithium intercalation concentration is exceeded, while the cathode is in a lithium-poor state, which can result in shortened battery lifespan and safety. In this work, the geometric structure of the positive electrode particles is designed based on the tomography data, while the negative electrode particles are represented by spheres with different sizes. The homogenization method is used, with the carbon filler, binder and electrolyte regarded as a single porous conductive adhesive domain. Based on the main mechanism of lithium-ion battery overcharge, a coupled three-dimensional electrochemical-mechanical-thermal overcharge model on a particle scale is developed for NCM cathode and graphite anode. The coupled mathematical model consists of four parts, namely the electrochemical model, the lithium plating model, the thermal model and the stress-strain model. In terms of lithium precipitation, the particle radius parameter and charging rates are investigated. The results show that the lithium plating concentration of the particles near the separator is higher, following the “principle of proximity” , namely the sequence of lithium deintercalation is related to the migration path. The surface of anode particles with small particle size is more prone to lithium precipitation due to the high maximum lithium ion concentration on the surface of the particles, the low surface lithium precipitation overpotential, and the high average Von Mises stress. At high charging rate, fast charge transfer rate and ion diffusion rate result in a low voltage at the anode, triggering off lithium precipitation. At a low rate, polarization and low temperature can lead to the precipitation of more lithium on the surface of the anode particles. In terms of stress, the spatial distribution between particles and thermal effects are investigated. The ratio of the distance from the contact surface to the center of the particle to the particle radius is calculated and defined as the contact depth (<inline-formula><tex-math id="M2">\begin{document}$Jr$\end{document}</tex-math></inline-formula>), in order to better describe the law of particle contact stress. It is shown that the contact depth between particles is inversely proportional to the stress on the contact area. When the heat generation effect is considered, the temperature of the battery rises faster with the increase of the charging rate. The electrochemical parameters related to temperature and the lithium concentration diffusion gradient increase significantly, and the influence of temperature on the particle stress is also more significant. The relevant results can provide theoretical basis and guidance for designing battery and optimizing charge strategies.

A general polarimetric model for transiting and nontransiting ringed exoplanets

Context. The detection and characterization of exorings (rings around exoplanets) will help us to better understand the origin and evolution of planetary rings in the Solar System and beyond. However, exorings are still elusive, and new and clever methods for identifying them need to be developed and tested. Aims. We explore the potential of polarimetry as a tool for discovering and characterizing exorings. Methods. For this purpose, we improved the general publicly available photometric code Pryngles by adding the results of radiative transfer calculations with an adding-doubling algorithm that fully includes polarization. With this improved code, we computed the total and polarized fluxes and the degree of polarization of model gas giant planets with or without rings. Additionally, we demonstrate the versatility of our code by predicting the polarimetric signal of the puffed-up planet HIP 41378 f as if it had an exoring. Results. Spatially unresolved dusty rings can significantly modify the flux and polarization signals of the light that is reflected by a gas giant exoplanet along its orbit. Rings are expected to have a low polarization signal, but they will decrease the degree of polarization of reflected light when they cast a shadow on the planet and/or block part of the planet. The most diagnostic feature of a ring occurs around the ring-plane crossings when sharp changes in the flux and degree of polarization curves are predicted by our model. When we applied our methods to HIP 41378 f, we found that if it is surrounded by a ring, noticeable changes in the degree of polarization of reflected light will arise. Although the reflected light on the planet cannot yet be directly imaged, the addition of polarimetry to future observations would aid in the characterization of the system.

Chiral perovskites with a unique 1D chain structure: impact of chiral ligand geometry on local inversion asymmetry and chiral-induced spin selectivity.

Chiral hybrid organic-inorganic perovskites (HOIPs) have demonstrated significant potential in spintronics, primarily due to inversion symmetry breaking as well as strong spin-orbit coupling (SOC) arising from their heavy-element composition. Numerous studies have confirmed that chiral perovskites exhibit superior chiral-induced spin selectivity (CISS). However, the key factors underlying such pronounced spin polarization selectivity, especially within organic-inorganic hybrid systems, are not well understood. This oversight marks a critical area for deeper exploration in spintronics research. We introduce R/S-1-amino-2-propanol (R/S-HP1A) as a chiral spacer to synthesize chiral perovskites, (R/S-HP1A)PbI3, characterized by a distinct 1D chain structure with two layers of inorganic octahedrons in each chain. In (R/S-HP1A)PbI3, the chiral carbon locates away from the perovskite's inorganic skeleton, resulting in a slight degree of inversion asymmetry within the inorganic sublattice while maintaining a global chiral space group (P212121). As a result, (R/S-HP1A)PbI3 exhibits small Rashba-Dresselhaus spin-splitting, a purely in-plane spin texture, a short spin lifetime (4 ± 1.5 ps) and a relatively low polarization degree of the CISS effect (58% and 66% for R- and S-forms, respectively), in comparison to other reported low-dimensional chiral perovskites. These findings emphasize that the local inversion asymmetry of the inorganic octahedrons, beyond global chirality, significantly influences the CISS effect in chiral perovskites, which is important for targeted improvements in spintronic applications.