Polarization Switching Research Articles

High-throughput UPLC-ESI/MSMS method for simultaneous measurement of the urinary metabolites of volatile organic compounds and tobacco alkaloids.

Human exposure to volatile organic compounds (VOCs) poses significant health risks, contributing to cardiovascular disease, pulmonary disease, and cancer. Measurement of VOC metabolites (VOCm) in urine by liquid chromatography-mass spectrometry (LC-MS) is a preferred method for VOCm analysis; however, existing methods encounter challenges related to sensitivity, throughput, and analyte coverage. In addition to VOCm, the measurement of tobacco alkaloids (TAm) is critical to account for tobacco use in population-based studies. A method is needed that is highly sensitive, offers higher throughput, and can analyze VOCm and TAm in a single run. Herein, we present a robust dilute-and-shoot method aimed at overcoming these analytical challenges and expanding the targeted analysis to include 35 urinary VOCm and TAm and their metabolites. By leveraging high-speed polarity switching and optimized chromatographic parameters, our method achieved comprehensive analyte coverage and enhanced sensitivity, enabling reliable individual level VOC exposure assessment. Validation demonstrates robust linearity, sensitivity, accuracy, and precision, with minimal matrix effects. This high-throughput UPLC-MS/MS method significantly enhances VOC exposure assessment by enabling simultaneous measurement of 35 urinary VOC and TAm with high sensitivity and efficiency. Multiple metabolites from single parent xenobiotics are included in one run, expanding biomarker specificity. Our data indicate the method effectively accounts for tobacco consumption as a confounder in population-based studies, ensuring accurate VOC exposure assessment.

Defective ground structure loaded polarization reconfigurable ring-shaped patch antenna for multiband applications

ABSTRACT A novel stub-loaded polarization-reconfigurable ring-shaped circular patch antenna designed for multi-band operation and switchable polarization is presented, having advantages such as ease in manufacturing and compact size (20 mm × 20 mm). The circular ring is segmented into four sectors, and two stubs are loaded on the inner side of the ring to disrupt the current distribution and create two orthogonal electric field vectors, generating circular polarization. The antenna supports it in switching three distinct polarization states: linear polarization, left-hand circular polarization, and right-hand circular polarization, selectable with different combinations of diodes. From the measured results, ARBW (<3 dB) is 32.12% and 6.06% for CP bands. Additionally, eight LP bands with IBW of 71.66%, 3.55%, 3.94%, 35.88%, 45%, 45.5%, 34.77%, and 8.2% are achieved. The antenna exhibits satisfactory stable gain across all frequency bands and excellent radiation performance, making it a promising candidate for modern wireless communication applications (C-band, ITS2 fixed, X-band, and Ku-band satellite downlink operations).

Reward based optimization of resonance-enhanced piezoresponse spectroscopy

Dynamic spectroscopies in scanning probe microscopy (SPM) are critical for probing material properties, such as force interactions, mechanical properties, polarization switching, electrochemical reactions, and ionic dynamics. However, the practical implementation of these measurements is constrained by the need to balance imaging time and data quality. Signal to noise requirements favor long acquisition times and high frequencies to improve signal fidelity. However, these are limited on the low end by contact resonant frequency and photodiode sensitivity and on the high end by the time needed to acquire high-resolution spectra or the propensity for sample degradation under high field excitation over long times. The interdependence of key parameters such as instrument settings, acquisition times, and sampling rates makes manual tuning labor-intensive and highly dependent on user expertise, often yielding operator-dependent results. These limitations are prominent in techniques like dual amplitude resonance tracking in piezoresponse force microscopy that utilize multiple concurrent feedback loops for topography and resonance frequency tracking. Here, a reward-driven workflow is proposed that automates the tuning process, adapting experimental conditions in real time to optimize data quality. This approach significantly reduces the complexity and time required for manual adjustments and can be extended to other SPM spectroscopic methods, enhancing overall efficiency and reproducibility.

Correlation between ferroelectricity and torsional motion of acetyl groups in tris(4-acetylphenyl)amine observed by muon spin relaxation

It is demonstrated by muon spin relaxation and resonance experiments that the switchable spontaneous polarization of the organic ferroelectric compound tris(4-acetylphenyl)amine is governed by the local molecular dynamics of the acetyl group. The implanted muon forms paramagnetic states, which exhibit longitudinal spin relaxation due to the fluctuation of hyperfine fields exerted from unpaired electrons. The first-principle density functional theory calculations indicate that these states are muonated radicals localized at the phenyl group and on the carbon/oxygen of the acetyl group, thereby suggesting that the spin relaxation is dominated by the random torsional motion of an acetyl group around the C–C bond to the phenyl group. The stepwise change in the relative yield of radicals at T0≈350 K and the gradual increase in the spin relaxation rate with temperature (T) indicate that the torsional motion is significantly enhanced by thermal excitation above T0. This occurs concomitantly with the strong enhancement in the atomic displacement parameter of oxygen in the acetyl group (which is non-linear in T), indicating that it is the local molecular motion of the acetyl groups that drives the structural transition.

Cross-Point Ferroelectric Hf0.5Zr0.5O2 Capacitors for Remanent Polarization-Driven In-Memory Computing.

Ferroelectric Hf0.5Zr0.5O2 (HZO) capacitors have been extensively explored for in-memory computing (IMC) applications due to their nonvolatility and back-end-of-line (BEOL) compatible process. Several IMC approaches using resistance and capacitance states in ferroelectric HZO have been proposed for vector-matrix multiplication (VMM), but previous approaches suffer from limited accuracy and reliability. In this work, we propose a promising approach centered on the remanent polarization (Pr) switching of binary ferroelectric HZO capacitor synapses. We experimentally demonstrate a simple pattern recognition task showing that the voltage readout of Pr switching provides excellent accuracy due to its high on/off ratio and consequent reliability. We also performed large-scale simulations on a complex inference task, achieving high accuracy and immunity to device variations. We therefore believe that our proposed paradigm is promising for near-term neuromorphic IMC.

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.

Switchable Hydrophilicity Amine Product Extraction: Efficient Separation of Tertiary Amines via Carbon Dioxide-Induced Polarity Switch in Homogeneous Catalysis

Switchable Hydrophilicity Amine Product Extraction: Efficient Separation of Tertiary Amines via Carbon Dioxide-Induced Polarity Switch in Homogeneous Catalysis

2D Van der Waals Sliding Ferroelectrics Toward Novel Electronic Devices.

Ferroelectric materials, celebrated for their switchable polarization, have undergone significant evolution since their early discovery in Rochelle salt. Initial challenges, including water solubility and brittleness, are overcome with the development of perovskite ferroelectrics, which enable the creation of stable, high-quality thin films suitable for semiconductor applications. As the demand for miniaturization in nanoelectronics has increased, research has shifted toward low-dimensional materials. Traditional ferroelectrics often lose their properties at the nanoscale; however, 2D van der Waals (vdW) ferroelectrics, including CuInP2S6 and α-In2Se3, have emerged as promising alternatives. The recent discovery of sliding ferroelectricity, where polarization is linked to the polar stacking configuration of originally non-polar monolayers, has significantly broadened the scope of 2D ferroelectrics. This review offers a comprehensive examination of stacking orders in 2D vdW materials, stacking-order-linked ferroelectric polarization structures, and their manifestations in metallic, insulating and semiconducting 2D vdW materials. Additionally, it explores the applications of 2D vdW sliding ferroelectrics, and discusses the future prospects innanotechnology.

High spin-orbit torque efficiency induced by engineering spin absorption for fully electric-driven magnetization switching.

Realizing spin-orbit torque (SOT)-driven magnetization switching offers promising opportunities for the advancement of next-generation spintronics. However, the relatively low charge-spin conversion efficiency accompanied by an ultrahigh critical switching current density (Jc) remains a significant obstacle to the further development of SOT-based storage elements. Herein, spin absorption engineering at the ferromagnet/nonmagnet interface is firstly proposed to achieve high SOT efficiency in Pt/Co/Ir trilayers. The Jc value was significantly decreased to 7.5 × 106 A cm-2, achieving a maximum reduction of 58% when a 4.0-nm Gd layer was inserted into the Co/Ir interface. A similar trend was observed in the trilayers with various rare metal insertions, suggesting the universality of this approach. Simultaneously, the highest effective spin Hall angle of 0.29 was obtained in the Pt/Co/Gd (4.0 nm)/Ir multilayers, which was approximately three times greater than that obtained in the Pt/Co/Ir trilayer. First-principles calculations together with polarized neutron reflectivity results revealed that spin mixed conductivity can be significantly enhanced due to a spontaneous interfacial CoGd alloy, which is critical for high SOT efficiency. In addition, the deterministic field-free switching polarity can be tuned by introducing Gd insertion. These findings provide a promising pathway for deeply understanding the spin-charge conversion mechanism, and further enable the design of low-consumption spintronic circuits.

Unconventional Ferroelectric-Ferroelastic Switching Mediated by Non-Polar Phase in Fluorite Oxides.

HfO2/ZrO2-based ferroelectrics present tremendous potential for next-generation non-volatile memory due to their high scalability and compatibility with silicon technology. Unlike the continuous polar layers in perovskite ferroelectrics, HfO2/ZrO2-based ferroelectrics are composed of alternating polar layers with oxygen shifts and non-polar spacers, which leads to a distinct ferroelectric switching mechanism. However, directly observing the switching process has been a big challenge due to the polymorph feature of nanoscale fluorites and the difficulty in in situ imaging on light elements. Here, the ferroelectric-ferroelastic coupled switching process in freestanding ZrO2 thin films is directly visualized by in situ imaging on oxygen motions. A multi-step 90-degree polarization switching mechanism is uncovered that challenges the conventional one-step 180-degree switching paradigms in fluorite oxides, which is highly consistent with the interlocked nature of ferroelectricity and ferroelasticity. A non-polar tetragonal (T) phase is discovered as a crucial intermediate state, lowering the energy barrier for polarization switching by 35%. More importantly, the T phase prevents irreversible transitions to the non-polar ground state and facilitates stable ferroelectric switching. These findings are fundamental to understanding nanoscale polarization switching mechanisms in fluorite ferroelectrics, paving the way for advanced high-durability devices.

Novel Magnetic-Field-Free Switching Behavior in vdW-Magnet/Oxide Heterostructure.

Magnetization switching by charge current without a magnetic field is essential for device applications and information technology. It generally requires a current-induced out-of-plane spin polarization beyond the capability of conventional ferromagnet/heavy-metal systems, where the current-induced spin polarization aligns in-plane orthogonal to the in-plane charge current and out-of-plane spin current. Here, a new approach is demonstrated for magnetic-field-free switching by fabricating a van-der-Waals magnet and oxide Fe3GeTe2/SrTiO3 heterostructure. This new magnetic-field-free switching is possible because the current-driven accumulated spins at the Rashba interface precess around an emergent interface magnetism, eventually producing an ultimate out-of-plane spin polarization. This interpretation is further confirmed by the switching polarity change controlled by the in-plane initialization magnetic fields with clear hysteresis. Van-der-Waals magnet and oxide are successfully combined for the first time, especially taking advantage of spin-orbit torque on the SrTiO3 oxide. This allows this study to establish a new way of magnetic field-free switching. This work demonstrates an unusual perpendicular switching application of large spin Hall angle materials and precession of accumulated spins, and in doing so, opens up a new field and opportunities for van-der-Waals magnets and oxide spintronics.

Data-Driven Discovery of High-Performance Heterobilayer Transition Metal Dichalcogenide-Based Sliding Ferroelectrics.

The development of efficient sliding ferroelectric (FE) materials is crucial for advancing next-generation low-power nanodevices. Currently, most efforts focus on homobilayer two-dimensional materials, except for the experimentally reported heterobilayer sliding FE, MoS2/WS2. Here, we first screened 870 transition metal dichalcogenide (TMD) bilayer heterostructures derived from experimentally characterized monolayer TMDs and systematically investigated their sliding ferroelectric behavior across various stacking configurations using high-throughput calculations. On the basis of the generated data, we developed an efficient descriptor, named the amplitude of Allen electronegativity difference (Δχm), for identifying van der Waals heterobilayers with sliding FE properties. Finally, 16 semiconducting TMD heterobilayers are identified as exhibiting interlayer sliding FE alongside low switching barriers (<21 meV/f.u.), with 10 outperforming the experimental MoS2/WS2 system, showing the largest out-of-plane polarization (OPP) values up to 10 times higher than MoS2/WS2. These materials exhibit favorable band gaps (0.60-1.80 eV) using the HSE06 method, making them suitable for sliding FE applications. Our findings reveal that polarization switching in these heterobilayers is strongly influenced by the interplay of stacking patterns, material electronegativity, charge transfer, and electronic structures. This study provides a robust framework for designing novel sliding ferroelectric materials and offers a theoretical basis for future experimental research.

Comprehensive untargeted polar metabolite analysis using solvent switching liquid chromatography tandem mass spectrometry.

Metabolomics analyses enable the examination and identification of endogenous biochemical reaction products, revealing information on the metabolic pathways and processes active within a living cell or organism. Determination of metabolic shifts can provide important information on a treatment or disease. Unlike other omics fields that typically have analytes of the same chemical class with common building blocks, those that fall under the nomenclature of metabolites encompass a wide array of different compounds with very diverse physiochemical properties. Development of a comprehensive metabolomic pipeline therefore can be a troublesome and complicated process for the analyst. Often single liquid chromatography-mass spectrometry methods on unfractionated samples are carried out in order to be time-efficient, however this could potentially produce data with a low number of identifiable metabolites. In the present studies, we developed a comprehensive polar metabolomics pipeline for cell-based metabolomics. SH-SY5Y neuroblastoma cells were selected as the sample matrix for method development since they are one of the most widely used cell lines for human neurotoxicity studies. This was accomplished by investigating and optimising different mass spectrometry source and chromatographic conditions to enhance the signal of polar metabolites. Optimised hydrophilic interaction liquid chromatography (HILIC) based metabolomic methods at different pH values were examined in positive, negative, and polarity switching modes to determine which combination yielded the highest number of confidently identified metabolites. Additionally, the use of sequentially running two methods was also compared to determine the degree of overlap and whether there is merit in running two separate methods on one sample. It was determined that solvent switching between two optimised methods, acidic chromatographic conditions in positive mode and basic chromatographic conditions in negative mode, yielded the highest number of unique identifiable metabolites. This could be run in a single analytical batch due to the large pH range of the column. A quick switch method in-between each method allowed both conditioning the column and preparation of the MS source conditions for the sequential method.

High AC field-induced polarization switching unraveled in frequency domain: Enhanced dielectric responses in lanthanum-doped Pb(Ni1/3Nb2/3)O3-Pb(Zr,Ti)O3 relaxor-ferroelectrics

In this study, we delve into the complex dielectric behaviors of lanthanum (La)-doped PNN-PZT relaxor-ferroelectric ceramics under the influence of high AC fields. Our approach involves a meticulous design of dielectric measurements to scrutinize the decoupling phenomenon between local polarization oscillation and global polarization switching. Remarkably, the application of high AC fields (&amp;gt;0.5 kV/mm) causes a dramatic increase in the dielectric permittivity (2x), alongside pronounced frequency dispersion (&amp;gt;65 °C) and a permittivity hump below Tm in 7% La-doped relaxor compositions. For relaxor-ferroelectric ceramics doped with lower La (&amp;lt;=5%) that are featured with tweed-like submicron domains as imaged in in situ transmission electron microscopy, the significantly enhanced dielectric permittivity and dielectric loss (&amp;gt;1) are induced under high AC fields (&amp;lt;0.5 kV/mm). A comparative study with a polarization loop in the time domain under various AC fields and DC bias demonstrates that the dielectric anomaly in the frequency domain is associated with global polarization switching, co-existing with polarization oscillation mechanism in various domains. This frequency domain method reveals threshold AC fields (0.25–0.5 kV/mm) above which polarization switching occurs in relaxor-FE compositions at elevated temperatures, complements the dynamic behaviors of P–E hysteresis, and cautions the control of AC fields in dealing with relaxor-ferroelectric materials for advanced electronic applications.

Dynamic change of polarity in spread through air spaces of pulmonary malignancies.

Spread through air spaces (STAS) is a histological finding of lung tumours where tumour cells exist within the air space of the lung parenchyma beyond the margin of the main tumour. Although STAS is an important prognostic factor, the pathobiology of STAS remains unclear. Here, we investigated the mechanism of STAS by analysing the relationship between STAS and polarity switching in vivo and in vitro. Histopathological analysis revealed that apical membranes were observed outside the STAS lesions around colorectal cancer (CRC) lung metastases and lung adenocarcinomas. When apical-out CRC organoids were administered intratracheally to mice, the organoids had greater metastatic potential than did single cells. To investigate the pathobiology of STAS, we established an in vitro model of STAS in which CRC or lung cancer organoids were co-cultured with 2D-cultured mouse airway epithelial organoids (2D-MAOs). Adhesion of cancer organoids to 2D-MAOs was much less than to type I collagen or endothelial cells, suggesting a protective role of the airway epithelium against adhesion. Loss of the apical membrane of CRC organoids at the contact surface with 2D-MAOs after adhesion was responsible for establishing adhesion. When airway epithelium was stimulated by transforming growth factor beta 1 (TGF-β1), adhesion of CRC organoids was enhanced. Among TGF-β1-induced genes in airway epithelium, follistatin-like protein 1 (FSTL1) increased CRC organoid adhesion by promoting loss of the apical membrane. These results suggested that TGF-β1-induced FSTL1 may promote metastatic progression of STAS by altering the polarity status. Elucidating the mechanism of STAS could contribute to the improvement of survival in patients with pulmonary malignancies associated with STAS. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Design of spike-timing-dependent plasticity synapses based on CoPt-SOT device and its application in all-spin spiking neural network

Spintronic could be used to simulate synapses or neurons due to its multistate storage characteristics. In this work, a reliable design of all-spin spiking neural networks (SNN) based on spin–orbit torque (SOT) devices has been proposed in A1 CoPt single layer. The CoPt-SOT devices exhibited field-free SOT switching, and the magnetization reversal mechanism was inferred to be a combination of domain nucleation and domain-wall propagation as observed through magneto-optical Kerr microscopy images. Moreover, the current-induced SOT switching process of the device exhibited stable multistate magnetic switching behavior, which can be controlled by varying the amplitude and pulse width of the current pulse. Meanwhile, the spike-timing-dependent plasticity (STDP) curve was inverted when the SOT switching polarity was reversed by different magnetic fields, and the change in anomalous Hall resistances (ΔRH) in the STDP curve was linearly related to the SOT switching ratio. In addition, at the zero magnetic field, we constructed an all-spin SNN using STDP synapses and leaky integrate-and-fire neurons of CoPt-SOT devices. The handwritten digits recognition rate of this all-spin SNN network was 89.9%. These results substantiate that the CoPt single layer represents a promising hardware solution for high-performance neuromorphic computing, with applicability in the domain of SNN.

Large Polarization Change Induced by Spin Crossover-Driven Fe(II) Ion Shuttling within a Tripodal Ligand.

The integration of spin crossover (SCO) magnetic switching and electric polarization properties can engender intriguing correlated magnetic and electric phenomena. However, achieving substantial SCO-induced polarization change through rational molecular design remains a formidable challenge. Herein, we present a polar Fe(II) compound that exhibits substantial polarization change in response to a thermally regulated low-spin ↔ high-spin transition. This large polarization change is realized by harnessing an unusual SCO-actuated large displacement of the Fe(II) ion, encapsulated within a cage-like tripodal ligand. Owing to the uniaxially aligned polar molecular structures within the lattice, alterations in the molecular dipole moment translate to notable polarization change of the single crystal with a value of 1.9 μC cm-2. This value is 2.4 times the highest value reported for SCO compounds. The large polarization change and small dielectric constant result in an outstanding pyroelectric response in this compound, with figures of merit comparable to those of typical pyroelectric materials. The intrinsic large displacement of the Fe(II) ion provides a new strategy to effectively modulate the electric polarization via SCO magnetic switching, and the ion shuttling within a cage structure may find applications in next-generation single-molecule magnetoelectric devices.

Structural changes during wake-up and polarization switching in a ferroelectric Hf0.5Zr0.5O2 film

Ferroelectric polycrystalline hafnium oxide films hold great promise for the electronics industry, though an understanding of ferroelectricity in this unconventional material is still lacking. Here, by an in situ synchrotron X-ray microdiffraction experiment, we reveal an important role of reversible and irreversible ferroelastic switching in the mechanism of polarization reversal in a 10 nm thick Hf0.5Zr0.5O2 film and in the origin of the so called wake-up effect consisting in a gradual increase in the remanent polarization of as-prepared memory structures. During the wake-up, the oblique polar axis irreversibly rotates in some ferroelectric orthorhombic grains and becomes more vertical on average in the film, which is the mechanism of the increase in measured polarization. This effect originates from the tensile stress emerging in the film during crystallization annealing and its gradual decrease via the rearrangement of the crystal lattice, which is consistent with first-principles calculations. In the woken-up structures, the polar axis also rotates during polarization switching, but reversibly, which means a different crystal structure of Hf0.5Zr0.5O2 in the upward and downward polarization states and breaking the inversion symmetry. The results provide insight into fundamentals of ferroelectric hafnium oxide and points the way for intelligent material engineering in the field of ferroelectrics-based devices.

Coexistence of altermagnetism and robust ferroelectricity in a bulk MnO wurtzite structure.

Altermagnetism is a new class of material with zero net magnetization, but having a nonrelativistic spin-split band structure. Here, we investigate the multifunctional properties of the hexagonal wurtzite MnO (w-MnO). w-MnO has a direct band gap of 0.39 eV and the altermagnetic behavior is achieved with a spin splitting of up to 188 meV. The bulk w-MnO has an in-plane magnetic anisotropy energy of -0.17 meV per cell along the [100] direction and temperature-dependent magnetization reveals a Néel temperature of around 180 K. Moreover, a maximum spin Hall conductivity of -285(ℏ/e) S cm-1 is obtained at a chemical potential of -0.24 eV. Along with the altermagnetism, we also find a large out-of-plane spontaneous polarization of 76.25 μC cm-2. w-MnO exhibits a low energy barrier of 0.26 eV per formula unit (f.u.) for polarization switching and this is further decreased to 0.15 eV per f.u. under 5% epitaxial tensile strain. The molecular dynamics simulations suggest that w-MnO retains its ferroelectric order below 2100 K indicating excellent thermal stability. These findings suggest that the hexagonal w-MnO can be a promising candidate for multiferroic applications particularly in spintronic and ferroelectric devices with high thermal stability.

Theoretical study on structural stability and miscibility of ScAlN alloys: effect of lattice constraint

Abstract The structural stability and miscibility of ScAlN are theoretically investigated on the basis of density functional calculations. The calculations demonstrate that the relative stability between wurtzite and rocksalt structures depends on Sc composition. The lattice constraint of AlN and GaN substrates enhances the stability of wurtzite structure as well as the miscibility of ScAlN alloys. Furthermore, the calculated energy barrier for polarization switching is also influenced by the lattice constraint. The results give insights for understanding the effect of substrate on structural stability and miscibility of ScAlN alloys.