Materials Science
Descriptor-Based Classification of Interfacial Electronic Coupling in Janus XP3-Based 2D Heterostructures
Erika N. Lima, Teldo A. S. Pereira, Elisangela S. Barboza et al. (+2 more)
Understanding and controlling interfacial electronic coupling in two-dimensional (2D)
heterostructures is essential for designing functional materials for electronic, optoelectronic, and catalytic applications. Here, we investigate vertical heterobilayers constructed from two distinct XP3 monolayers (X = As, Ge, Sb, Bi, Sn, Al, Ga, and Pb) using first-principles density functional theory. The resulting Janus heterobilayers are energetically favorable and elastically stable, with electronic band gaps ranging from metallic and near-metallic to semiconducting regimes. Interlayer interactions induce significant band renormalization, including transitions between type I and type II
alignment upon structural relaxation. To rationalize these effects, we establish a descriptor-based framework based on the metal metal interlayer distance, interfacial electron localization, and Bader charge redistribution. This combined analysis discriminates vdW-like, polar covalent, and ionic interaction regimes, with systematic trends governed by the average atomic number of the constituent elements. Optical absorption calculations indicate visible-to-near-infrared activity in selected systems, and band-edge
alignment identifies promising candidates for selective redox processes. Overall, the proposed descriptor-based strategy provides a physically grounded route for identifying and engineering interfacial coupling in XP3
heterostructures and can be extended to other classes of two-dimensional material interfaces.
Read the full abstract ▾
All authors Erika N. Lima, Teldo A. S. Pereira, Elisangela S. Barboza, Dominike Pacine, Igor S. S. de Oliveira
Materials Science
Mechanical Control of Polar Order
Pushpendra Gupta, Peter Meisenheimer, Xinyan Li et al. (+5 more)
BiFeO3 is a model multiferroic in which the ferroelectric polarization is coupled to ferroelastic
lattice distortions, yet deterministic control of its domain structure remains limited by high switching fields and competing polarization variants. Here, we identify a mechanically assisted polarization switching pathway in epitaxial BiFeO3 thin films that fundamentally alters the switching energetics. Using just out-of-plane electric fields, polarization reversal requires voltages of approximately 4 V and stabilizes coexisting polarization states. In contrast, when mechanical pressure is applied concurrently, the coercive voltage can be significantly reduced (even to 0V), resulting in spontaneous switching. Piezoresponse force microscopy measurements reveal that applied mechanical pressure suppresses ferroelastic domain competition, indicating a decrease in the required electrical energy barrier associated with polarization rotation and domain wall motion. These results demonstrate that stress acts as an active thermodynamic control parameter, enabling access to switching pathways that are inaccessible under only an electric field. By directly coupling
lattice distortions to polarization reversal, mechanically assisted switching provides a general framework for controlling coupled order parameters in multiferroic
oxides, which can be directly applied in the device-level architecture, where a small mechanical pressure can help in achieving lower switching energy of ferroelectric polarization. This work advances the fundamental understanding of electromechanical coupling in complex ferroics and establishes mechanical energy as a powerful tool for probing and manipulating ferroelastic ferroelectric interactions.
Read the full abstract ▾
All authors Pushpendra Gupta, Peter Meisenheimer, Xinyan Li, Sajid Husain, Vishantak Srikrishna, Ashley Cortesis, Yimo Han, Ramamoorthy Ramesh
Materials Science · Cross-listed from physics.optics
A Route to Pure Optical Rotation in Self-Assembled Materials through Energetic Non-Degeneracy
Daniel J. Gracias, Thomas J. Ugras and Richard D. Robinson
Achieving large optical rotation with minimal ellipticity and absorption, 'pure' optical rotation, remains a central challenge in
chiral photonics. Solution-processed self-assembled materials can exhibit exceptional chiroptical responses (g-factors > 1), yet their circular birefringence (CB) typically overlaps with circular dichroism (CD) and resonant loss (Absorption), leading to elliptical, attenuated signals. Here, we establish a general, theory-guided design principle showing that non-degeneracy provides a route towards pure optical rotation in self-assembled systems. Using a generalized coupled-oscillator framework, we demonstrate that breaking degeneracy between the excited states of interacting chromophores produces CB in spectral regions where CD and absorption are naturally weak. We experimentally validate this mechanism using mixed assemblies of $\alpha$- and $\beta$-CdS magic-sized clusters, which exhibit the predicted off-resonant, emergent CB. Guided by this principle, we design a layered architecture that maximizes non-degenerate neighbors through alternating chromophore planes. This structural architecture results in optical response lineshapes optimized for pure rotation. Because the mechanism relies solely on dipolar coupling and energetic detuning, it is generalizable across wavelengths, including in the ultraviolet (~310 nm), where suitable nanocrystal and organic chromophores are readily available. Simulations predict a 50 meV (12 THz) window exhibiting low-dispersion optical rotation of ~20{\deg}, >40% transmission, and <1{\deg} ellipticity-strong performing
benchmarks typically associated with lithographic metamaterials. These results establish non-degenerate coupling as a general mechanism for engineering chiroptical response and provide a strategy for realizing pure optical rotation in self-assembled systems.
Read the full abstract ▾
Materials Science · Cross-listed from cond-mat.str-el
Anomalous Thermal Conductivity Reversal Driven by a Fluctuating Charge Density Wave
Han Huang, Jinghang Dai, Joyce Christiansen-Salameh et al. (+14 more)
For more than a century, the
lattice thermal conductivity of crystalline solids has been known to decrease with increasing temperature, as the
phonons that carry heat scatter more strongly via Umklapp processes. Here we report a pronounced violation of this rule in the layered charge-density-wave (CDW) metal 2H-TaSe2. Its in-plane thermal conductivity is strongly nonmonotonic: it peaks sharply at the 122 K ordering transition, collapses to a deep minimum near 210 K, and then anomalously reverses, rising with temperature to at least 350 K. Such a high-temperature reversal, in which a
crystal conducts heat more efficiently as it is heated, is rare in crystalline solids. Its thermal conductivity minimum lies deep in the disordered phase well above the ordering transition, unlike the weak, transition-centered anomalies of other charge-density-wave systems, pointing to heat conduction governed by fluctuating rather than established order. Combining inelastic X-ray scattering, selected-area electron diffraction, and synchrotron X-ray diffraction, we attribute the reversal to
phonons scattering off persistent, fluctuating charge order that survives more than 150 K above the long-range transition, to at least 300 K. A phenomenological
phonon-CDW scattering model, tied directly to the measured diffraction linewidth and intensity, quantitatively reproduces the entire nonmonotonic curve. We also reveal that the charge order melts not abruptly but through a fluctuation- and defect-driven, weak first-order process, leaving short-range correlations far above the transition. This work establishes fluctuating charge order as a sensitive control knob for thermal transport in
quantum materials and thermal conductivity as a powerful probe of the hidden charge order.
Read the full abstract ▾
All authors Han Huang, Jinghang Dai, Joyce Christiansen-Salameh, Jiyoung Kim, Samuel Kielar, Desheng Ma, Noah Schinitzer, Danrui Ni, Gustavo Alvarez, Chen Li, Carla Slebodnick, Mario Medina, Bilal Azhar, Ahmet Alatas, Robert Cava, David Muller, Zhiting Tian
Materials Science · Cross-listed from physics.med-ph
The FLASH enigma
Diana Shvydka, Victor Karpov and Nilendu Gupta
We consider physics behind the FLASH modality of cancer radiation treatment where extremely short treatment times are achieved with ultra high dose rates maintaining the conventional antitumor effectiveness and yet substantially reducing damage to normal tissues (sparing effect). The difference in responses between normal and tumor tissues is attributed here to different recombination rates related to their structure morphologies: ordered in normal vs disordered in the tumor tissues. Correspondingly different are their charge densities under ionizing radiation. In normal tissues it is high enough to form electron-hole
liquid (EHL). Because of low EHL diffusivities, the chemical reaction and generation of free radicals are suppressed; hence, sparing effect. To the contrary, a disordered tumor tissue renders efficient energy relaxation channels forming antitumor free radicals. We describe the FLASH thresholds for doses and dose rates.
Read the full abstract ▾
Materials Science
Tuning the optoelectronic properties of graphene quantum dots by BN-ring doping: A density functional theory study
Samayita Das and Alok Shukla
Graphene monolayer is a material with zero band gap, because of which its applications in optoelectronics are limited. The question arises, can we modify the optoelectronic properties of
graphene by doping it with other atoms? Synthesis of 2D monolayer of
graphene doped with hetero-atoms such as boron and nitrogen, and a few computational studies of their structural and electronic properties were previously reported. In this work, we aim to answer this question for
graphene quantum dots (GQDs) by replacing their carbon rings with $(BN)_3$ (borazine) hexagonal rings. We have studied in detail the geometry, electronic structure, and optical absorption spectra of fourteen different borazine-ring doped diamond-shaped GQDs using first-principles density functional theory (DFT). These BN-GQDs differ in the location, orientation, and the number of borazine rings. We computed their optical absorption spectra using time-dependent DFT (TDDFT) and examined: (a) for single-ring doped BN-GQDs the influence of ring location on optical properties, and (b) for double-ring doped systems, the influence of location, mutual distance and orientation of the rings on their absorption spectra. Frontier molecular orbitals are studied in detail to understand the nature of low-lying optical excitations. We also performed a group-theoretic analysis of the influence of their reduced
symmetries on their optical properties. Our results indicate that BN-ring doping can achieve significant control over the optical properties of GQDs. The comparison of the optical absorption spectra of the BN-GQDs with the parent GQD shows remarkable spectral broadening with optical gap spanning over infrared to visible region. Thus, systematic BN-ring doping provides easy tunability of the electronic and optical properties of BN-GQDs, which is very promising for optoelectronic applications.
Read the full abstract ▾
Materials Science
Assessing the suitability of the Thomas-Fermi-von Weizsäcker density functional for itinerant magnetism
Bishal Thapa, Phanish Suryanarayana and Igor I. Mazin
We assess the ability of the Thomas–
Fermi–von Weizsacker (TFW) functional within orbital-free density functional theory (DFT) to describe itinerant magnetism.
Magnetic stability is evaluated through the susceptibility obtained from the second derivative of the total energy with respect to the net magnetization. Calculations are performed for the paramagnetic metals Al and Pd and the canonical ferromagnets Fe, Co, and Ni, with the results benchmarked against Kohn–Sham DFT. The orbital-free results show poor agreement with the Kohn–Sham predictions, failing to capture even the qualitative trends. Using the orbital-free ground-state density with the Kohn–Sham functional in a non-self-consistent calculation yields reasonable qualitative agreement, although the quantitative agreement remains limited. These results highlight fundamental limitations of the TFW functional for describing itinerant magnetism.
Read the full abstract ▾
Materials Science
Synthesis and Transfer of Freestanding Strain-Engineered Vertically Aligned Nanocomposite Thin Films
Carlos Rodríguez Cortéz, Moussa Mebarki, Bruno Berini et al. (+11 more)
The recent development of freestanding
oxide thin films opens up exciting opportunities for the design of novel
heterostructures with enhanced functionalities. Here, we explore the fabrication of membranes consisting of dense arrays of ultrathin CoxNi1-x nanowires epitaxially embedded in a SrTiO3
matrix. Through combined x-ray absorption spectroscopy, x-ray resonant
magnetic scattering, x-ray diffraction and magnetooptical experiments, we show how a SrVO3-mediated lift-off process can be used to create and transfer these membranes while simultaneously preserving the structural and chemical integrity of the self-assembled, metallic CoxNi1-x nanopillars. With this approach, the large axial deformation of the embedded nanostructures is kept intact and, as a direct consequence, the
magnetic properties of the nano-composite thin films remain largely unaltered after substrate removal. Our findings thus highlight a novel route for the synthesis of freestanding, strain-engineered vertically aligned
heterostructures and pave the way for their future integration into spintronic and optomagnetic devices.
Read the full abstract ▾
All authors Carlos Rodríguez Cortéz, Moussa Mebarki, Bruno Berini, Dominique Demaille, Vincent Polewczyk, Yunlin Zheng, Pal Bhuyan, Boris Vodungbo, Emmanuelle Jal, Horia Popescu, Nicolas Jaouen, Yves Dumont, Marcel Hennes, Franck Vidal
Materials Science
LLM-Driven Discovery of High-Entropy Catalysts via Retrieval-Augmented Generation
AI Scientists, Xinyi Lin, Danqing Yin et al. (+1 more)
CO2 reduction requires efficient catalysts, yet materials discovery remains bottlenecked by 10-20 year development cycles requiring deep domain expertise. This paper demonstrates how large
language models can assist the catalyst discovery process by helping researchers explore chemical spaces and interpret results when augmented with
retrieval-based grounding. We introduce a
retrieval-augmented generation framework that enables GPT-4 to navigate chemical space by accessing a database of 50,000+ known materials, adapting general-purpose
language understanding for high-throughput materials design. Our approach generated over 250 catalyst candidates with an 82% thermodynamic stability rate while addressing multi-objective constraints: 68% achieved <$100/kg cost with metallic conductivity (band gap<0.1eV) and mechanical stability (B/G>1.75). The best-performing Fe0.2Co0.2Ni0.2Ir0.1Ru0.3 achieves 0.285V limiting potential (25% improvement over IrO2), while Cr0.2Fe0.2Co0.3Ni0.2Mo0.1 optimally balances performance-cost trade-offs at $18/kg. Volcano plot analysis confirms that 78% of LLM-generated catalysts cluster near the theoretical activity optimum, while our system achieves 200x computational efficiency compared to traditional high-throughput screening. By demonstrating that
retrieval-augmented generation can ground AI creativity in physical constraints without sacrificing exploration, this work demonstrates an approach where natural
language interfaces can streamline materials discovery workflows, enabling researchers to explore chemical spaces more efficiently while the LLM assists in result interpretation and hypothesis generation.
Read the full abstract ▾
All authors AI Scientists, Xinyi Lin, Danqing Yin, Ying Guo
Materials Science · Cross-listed from cond-mat.stat-mech
Non-Thermal Aging of Supercooled Liquids in Optical Cavities
Muhammad R. Hasyim, Arianna Damiani and Norah M. Hoffmann
Aging is a hallmark of disordered materials such as glasses, plastics, and pharmaceuticals, where it often limits long-term stability and performance. In practice, aging is controlled through global parameters like temperature or pressure, which act uniformly on the entire system. Here we introduce a fundamentally different approach, using light confined in optical cavities as a precise and selective tool to guide aging dynamics. We show that a supercooled
liquid coupled to an optical cavity undergoes non-thermal aging, where aging is induced by light without a thermal quench. Light selectively pumps fast vibrational modes while the bath temperature remains unchanged, reshaping the slow structural dynamics of the
liquid. The cavity-coupled
liquid thereby behaves as if it were structurally colder than its surroundings. Exploiting this effective structural cooling together with the timescale separation, we introduce cavity configurational feedback ($\mathrm{C^2F}$) cooling, which uses cavity coupling to reach progressively lower structural temperatures. Our results establish a connection between glass physics and strong light-matter interactions and open a new route toward optical control of aging, glass formation, and nonequilibrium materials dynamics.
Read the full abstract ▾
Materials Science
Benchmarking Machine Learning Approaches for Polarization Mapping in Ferroelectrics Using 4D-STEM
Matej Martinc, Goran Dražič, Anton Kokalj et al. (+5 more)
Four-dimensional scanning transmission electron microscopy (4D-STEM) provides rich, atomic-scale insights into materials structures. However, extracting specific physical properties - such as polarization directions essential for understanding functional properties of ferroelectrics - remains a significant challenge. In this study, we systematically
benchmark multiple machine learning models, namely ResNet, VGG, a custom convolutional neural network, and PCA-informed k-Nearest Neighbors, to automate the detection of polarization directions from 4D-STEM diffraction patterns in ferroelectric potassium sodium niobate. While models trained on synthetic data achieve high accuracy on idealized synthetic diffraction patterns of equivalent thickness, the domain gap between simulation and experiment remains a critical barrier to real-world deployment. In this context, a custom made prototype representation training regime and PCA-based methods, combined with data augmentation and filtering, can better bridge this gap. Error analysis reveals periodic missclassification patterns, indicating that not all diffraction patterns carry enough information for a successful classification. Additionally, our qualitative analysis demonstrates that irregularities in the model's prediction patterns correlate with defects in the
crystal structure, suggesting that supervised models could be used for detecting structural defects. These findings guide the development of robust, transferable machine learning tools for electron microscopy analysis.
Read the full abstract ▾
All authors Matej Martinc, Goran Dražič, Anton Kokalj, Katarina Žiberna, Janina Roknić, Matic Poberžnik, Sašo Džeroski, Andreja Benčan Golob
Materials Science
Engineering van der Waals heterostructures for dispersion-selective meV-scale quantum sensing
Elizabeth A. Peterson
Quantum sensing of meV-scale scattering and absorption of impinging particles with electrons in solid state detectors is a challenging technological advancement with the potential to enable breakthroughs in
quantum information applications and studies of fundamental physics. However, a key obstacle for current sensing schemes is the difficulty in distinguishing the signals from particles of interest and from intrinsic excitations, like
phonons or
magnons. Here we propose a technique to selectively detect impinging particles based not only on their imparted energy, but specifically by their dispersion relations. By harnessing interfacial orbital hybridization in van der Waals
heterostructures of Dirac materials, interlayer charge transfer may be promoted only for pre-selected impinging particles of interest. Using first-principles density functional theory (DFT) calculations of
heterostructures of the layered Dirac materials ZrTe5 and HfTe5, we examine the effects of strain and layer number for successfully tuning orbital hybridization in their electronic structure. We demonstrate a proof-or-principle feasibility study for using Dirac materials to construct dispersion filters to be leveraged for next-generation meV-scale
quantum sensors.
Read the full abstract ▾
Materials Science
High-Throughput Computational Exploration of MOFs for Short-Chain PFAS Removal
Mengru Zhang, Satyanarayana Bonakala, Taku Watanabe et al. (+2 more)
Short-chain per- and polyfluoroalkyl substances (PFASs) are increasingly replacing regulated long-chain PFASs, yet they remain challenging to remove from water due to their high persistence, mobility, and weak affinity toward conventional adsorbents. In this work, we developed a hybrid high-throughput computational screening (HTCS) strategy to identify high-performance MOFs for the selective adsorption of perfluorobutanoic acid (PFBA), a representative short-chain PFAS, from water. The workflow begins with a curated MOF
dataset and employs Monte Carlo (MC) simulations based on synergistic use of a classical universal force field (UFF) and a universal machine-learned interatomic potential (u-MLIP), enabling scalable and quantitatively accurate prediction of adsorption across large MOF databases. A set of promising MOFs initially identified using UFF-based HTCS, that combine strong PFBA affinity and high PFBA/H2O selectivity were re-evaluated with u-MLIP to refine adsorption predictions and to assess guest-induced framework flexibility, enabling the exclusion of materials with unfavourable high water-framework interactions. Ultimately, four high-performance MOFs were identified that optimally balance strong PFBA interactions, high PFBA selectivity over water, and practical considerations including sustainability, water stability, and synthetic feasibility. This study demonstrates that combining classical force fields with u-MLIPs enables scalable, quantitatively accurate MOF adsorption screening and establishes transferable principles for the rational design of adsorbents targeting short-chain PFAS.
Read the full abstract ▾
All authors Mengru Zhang, Satyanarayana Bonakala, Taku Watanabe, Karim Hamzaoui, Guillaume Maurin
Materials Science
Agentic workflow enables the recovery of critical materials from complex feedstocks via selective precipitation
Andrew Ritchhart, Sarah I. Allec, Pravalika Butreddy et al. (+5 more)
We present a multi-agentic workflow for critical materials recovery that deploys a series of AI
agents and automated instruments to recover critical materials from produced water and magnet leachates. This approach achieves selective precipitation from real-world feedstocks using simple chemicals, accelerating the development of efficient, adaptable, and scalable separations to a timeline of days, rather than months and years.
Read the full abstract ▾
All authors Andrew Ritchhart, Sarah I. Allec, Pravalika Butreddy, Krista Kulesa, Qingpu Wang, Dan Thien Nguyen, Maxim Ziatdinov, Elias Nakouzi
Materials Science · Cross-listed from cond-mat.str-el
Single-Crystal Growth and Physical Properties of the Antiferromagnetic Double Perovskite Ba_2CoMoO_6
A.R.N. Hanna, M. M. Ferreira-Carvalho, S.H. Chen et al. (+6 more)
This work presents a comprehensive investigation of the structural,
magnetic, and electronic properties of the double perovskite Ba$_2$CoMoO$_6$ (BCMO). Single
crystals were grown via floating-zone and Czochralski growth techniques and characterized using a set of complementary methods. X-ray diffraction analysis confirmed that BCMO crystallizes in a face-centered cubic (FCC) structure with space group $Fm\overline{3}m$.
Magnetic susceptibility measurements exhibit
antiferromagnetic ordering below $T_{\mathrm{N}} = 20.1(1)$~K. A
spin-flop transition is observed at 26.5~kOe. Heat capacity measurements and
entropy analysis are consistent with a $J_{\mathrm{eff}} = 1/2$ ground state for Co$^{2+}$ ions. X-ray absorption spectroscopy provided insight into the local electronic structure, revealing the
spin-orbit and
crystal field effects. The cluster-model analysis yields a $g$-factor of 4.36, consistent with a
spin-orbit-entangled ground state. Surface photovoltage spectroscopy demonstrates a strong near surface optical response with an onset near 1.5~eV and a pronounced feature at 2.65~eV, consistent with visible range Co–O–Mo transitions in line with related Ba-based double perovskites, highlighting its potential for spintronic and energy conversion applications.
Read the full abstract ▾
All authors A.R.N. Hanna, M. M. Ferreira-Carvalho, S.H. Chen, C. F. Chang, C. Y. Kuo, A.T.M.N. Islam, R. Feyerherm, L.H. Tjeng, B. Lake
Materials Science
Understanding early stages of low-temperature hydrogen-driven direct co-reduction of Fe-Ni mixed oxide thin films at the near atomic scale
Emmanuel Uwayezu, Shaolou Wei, Yujiao Li et al. (+3 more)
Kinetic understanding of hydrogen co-reduction of multinary and multi-phase
oxides is of interest for enhancing sustainability of
alloy production and transition to a hydrogen-based economy. Benefits include decrease in energy consumption, enhanced kinetics, and conversion of
oxides to
alloys. Thin films provide a platform to study these processes as reactive co-deposition from multiple elemental,
alloy or compound targets and precise oxygen flow control allow atomic mixing into various
oxide phases which are well-defined nanoscale precursor structures for the subsequent reduction study at the near atomic scale. The early stages of hydrogen direct reduction of
oxide thin films are investigated using a Fe50Ni50Ox thin film consisting of NiFe2O4 and NiO phases. After reduction at 280 C in pure H2 for different times, structural, morphological, and nanoscale changes were examined by different characterisation methods including atom probe
tomography (APT). The low-temperature reduction is nucleation-limited marked by grain-boundary nucleation preceded by an incubation time of more than 5 min. APT revealed that the early-stages of the reduction involves phase separation into a Ni-rich FexNiy metallic phase and a transformed remaining
oxide (magnetite, Fe3O4). Further reduction induces magnetite reduction and alloying into a nearly equiatomic FeNi
alloy. The low-temperature reduction and alloying are facilitated by synergetic effects from the nanostructure of the film, and Ni autocatalytic effects through alloying and hydrogen spillover. The results pave the way for low-temperature formation of Fe-Ni
alloy thin films with tunable compositions directly from
oxides, and broaden the scope of hydrogen direct reduction of multinary
oxides to thin-film platforms.
Read the full abstract ▾
All authors Emmanuel Uwayezu, Shaolou Wei, Yujiao Li, Johannes D. Bartl, Dierk Raabe, Alfred Ludwig
Materials Science
Microstructural characteristics, atomic-scale features, and growth mechanisms of deuterides (hydrides) in hafnium
Di Wang, Catriona M McGilvery, James O Douglas et al. (+1 more)
Hafnium hydride is a promising material for next-generation
nuclear reactors, particularly as control rods for fast fission and shielding in fusion systems. The material's intrinsic brittleness encourages its use in the form of hydride-metal composites, where the functional and mechanical performance is strongly influenced by the multiscale structure of hydride-
matrix interfaces. In this study, we employ a suite of microscopy techniques, including scanning electron microscopy with electron backscatter diffraction, transmission electron microscopy with electron energy-loss spectroscopy, and atom probe
tomography, to investigate the deuteride-
matrix interfaces in a deuterium-charged Hf
alloy. We characterise their structure and chemistry, extracting key information including the deuteride-
matrix crystallographic orientation relationship, microstructural features, misfit-induced dislocation distributions, electron energy-loss characteristics, and the segregation of oxygen during deuteride growth. These findings help clarify the mechanisms of interface
evolution and may contribute to improved understanding of hydride-metal systems, with potential relevance for their processing, performance, and design in
nuclear applications.
Read the full abstract ▾
All authors Di Wang, Catriona M McGilvery, James O Douglas, Siyang Wang
Materials Science
Epitaxial growth of topological insulator $\beta$-Ag2Te thin films
Ayuki Takegawa, Kouya Imoto, Minoru Kawamura et al. (+2 more)
We report epitaxial growth of $\beta$-Ag2Te thin films by molecular beam epitaxy. $\beta$-Ag2Te, recently identified as a topological
insulator, was grown by depositing Ag on InP substrate at room temperature followed by Te supply at elevated temperature. X-ray diffraction measurements and transmission electron microscopy analyses confirmed the (002)
crystal orientation and the epitaxial atomic arrangement of $\beta$-Ag2Te thin films. Electrical transport measurements revealed that the $\beta$-Ag2Te thin film exhibits two-dimensional metallic conduction while the bulk remains insulating. The epitaxial $\beta$-Ag2Te thin films obtained here provide a viable platform for investigating emergent phenomena arising from surface Dirac states and for designing heterojunction-based device structures.
Read the full abstract ▾
All authors Ayuki Takegawa, Kouya Imoto, Minoru Kawamura, Moeta Tsukamoto, Ryutaro Yoshimi
Materials Science
Polar Charge-Ordered States in BiFeO$_3$/CaFeO$_3$ Superlattice
Rajan Gowsalya, Monirul Shaikh, Sathiyamoorthy Buvaneswaran et al. (+1 more)
Oxide superlattices represent a potent avenue for tailoring emergent electronic phases through sophisticated interfacial charge transfer and dynamic
lattice distortions. This study systematically investigates the structural and electronic attributes of the BiFeO$_3$/CaFeO$_3$ superlattice, leveraging a comprehensive approach that integrates first-principles computations with detailed
symmetry-mode analysis. The strategic integration of polar bismuth ferrite alongside charge-transfer calcium ferrite instigates profound
lattice instabilities, notably manifest in octahedral rotations and cooperative FeO$_6$ breathing modes that might not necessarily be soft. However, their synergistic coupling stabilizes a non-centrosymmetric $Pc$ ground state that intrinsically features polar charge ordering of Fe ions. This resultant phase ingeniously unifies C-type antiferromagnetism with robust ferroelectric
semiconductor characteristics, exhibiting a calculated indirect band gap of about 0.6 eV. Our discoveries firmly establish ferrite superlattices as an exceptionally versatile and tunable platform for the rational design of next-generation multifunctional materials, offering precise control over polarization, charge ordering phenomena, and electronic transport behavior via advanced interface and strain engineering techniques.
Read the full abstract ▾
All authors Rajan Gowsalya, Monirul Shaikh, Sathiyamoorthy Buvaneswaran, Saurabh Ghosh
Materials Science · Cross-listed from cond-mat.mes-hall
Low-frequency noise as a probe of microscopic disorder in CVD-grown graphene
Jagadis Prasad Nayak, Smrutirekha Sahoo, Shreya Barman et al. (+1 more)
We report a detailed investigation of low-frequency resistance fluctuations (1/f noise) in chemical vapor deposition (CVD) grown
graphene. Systematic measurements reveal that the magnitude of 1/f noise in CVD-grown
graphene is significantly higher by several orders of magnitude than that typically observed in exfoliated single-
crystal graphene. This enhancement is attributed to structural imperfections such as grain boundaries and defect states within the polycrystalline film. Detailed analysis of the temperature dependence of the noise demonstrates that the resistance fluctuations arise from thermally activated dynamics of localized defects. These results provide key insights into the microscopic mechanism of noise in scalable
graphene films and highlight the role of defect engineering in optimizing
graphene for large-scale electronic applications. Our findings establish low-frequency noise as a sensitive probe of microscopic disorder in CVD
graphene, providing a practical pathway for assessing material quality in scalable electronic technologies.
Read the full abstract ▾
All authors Jagadis Prasad Nayak, Smrutirekha Sahoo, Shreya Barman, Gopi Nath Daptary
Materials Science
Will it form a glass? Tackling glass formation using binary classification
Diogo P. L. Carvalho, Ana C. B. Loponi and Daniel R. Cassar
Glass formation is one of the most important and fundamental open problems in glass science. Predicting whether a
liquid can be easily frozen into a glass appears simple but is far from it. In this communication, we address glass formation in inorganic nonmetallic
liquids using binary classification to predict the probability that a given
liquid will form a glass under typical laboratory conditions. Using a
dataset of more than 50,000 examples, we trained random forest classifiers that achieved ROC-AUC values around 0.89 and PR-AUC close to 0.95 on the holdout
dataset (i.e., unseen data). A rigorous model selection routine was employed, including hyperparameter tuning with cross-validation, and four different data treatment routes were evaluated. Using SHAP values, we extracted valuable insights from the trained models that both agree with established knowledge and extend it. For example, we identified that the bandgap energy of the constituent chemical elements is positively correlated with glass formation. When glass stability parameters and Jezica were added to the
dataset, no performance improvement was observed, but model complexity decreased significantly. This result is particularly relevant for composition screening, especially in inverse design problems.
Read the full abstract ▾