Materials Science
Comparative high-pressure study on rare-earth entropy fluorite-type oxides
Pablo Botellaa, David Vie, Leda Kolarek et al. (+6 more)
We report a comparative high-pressure study of two fluorite-type rare-earth
oxides with increasing configurational
entropy, (CePr)O$_{2-{\delta}}$ and (CePrLa)O$_{2-{\delta}}$. Synchrotron-based powder X-ray diffraction and Raman spectroscopy were carried out up to 30 GPa and 20 GPa, respectively. Both compounds retain the cubic fluorite structure throughout the pressure range explored, although an anomaly is observed between 9-16 GPa, characterized by a compressibility plateau and changes in vibrational modes. This behavior is attributed to local
lattice distortions and a progressive bond angle bending rather than abrupt phase transitions. In (CePrLa)O$_{2-{\delta}}$, the onset of amorphization is observed above 22 GPa, highlighting its reduced structural stability. The bulk modulus of both systems shows a slight decrease after the onset of the anomaly, suggesting subtle
lattice softening. Raman spectroscopy reveals suppression of the F$_{2g}$ mode intensity with increasing cationic disorder, and under compression, partial reordering is evidenced by an increase in the RE-O mode intensity. Our results highlight the complex interplay between configurational
entropy, cation size, and pressure in determining the structural stability and vibrational properties of rare-earth high-
entropy oxides and provide insight into the mechanisms governing their resilience and local disorder under extreme conditions.
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All authors Pablo Botellaa, David Vie, Leda Kolarek, Neha Bura, Peijie Zhang, Anna Herlihy, Dominik Daisenberger, Catalin Popescu, Daniel Errandonea
Materials Science
2D Ferroelectric Ruddlesden-Popper Perovskites: an Emerging Fully Electronically Controllable Shift Current and Persistent Spin Helix
Yue Zhao, Fu Li, Vikrant Chaudhary et al. (+5 more)
Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) are promising candidates for next-generation optoelectronic and spintronic applications. This work systematically investigates the relationship between structural distortions and functional responses in three $C_{2v}$-symmetric Ruddlesden–Popper (RP) ferroelectric perovskites, $(4,4\text{-DFPD})_{2}\mathrm{PbI}_{4}$, $(\mathrm{DFCHA})_{2}\mathrm{PbI}_{4}$, and PEPI, using first-principles calculations combined with irreducible representation decomposition and wave-vector point-group
symmetry (WPGS) analysis. The results reveal that the lead–iodide framework yields shift-current (SC) magnitudes comparable to, and in specific cases even an order of magnitude larger than, those of traditional ferroelectric
oxides, with PEPI reaching a maximum of $69.16\ \mu\mathrm{A}/\mathrm{V}^{2}$. The SC magnitude correlates positively with the octahedral distortion index ($D_i$), while a competition mechanism is identified between covalent bond strength and structural asymmetry, where increased average bond lengths can offset the enhancement induced by $D_i$. Regarding spintronics, $C_{2v}$
symmetry-protected persistent
spin textures (PST) are identified. A transition to $C_2$-protected quasi-PST occurs in monoclinic $(4,4\text{-DFHHA})_{2}\mathrm{PbI}_{4}$, leading to a persistent
spin helix (PSH) with long-distance
spin transport. The synergy among ferroelectricity, SC, and PST enables nonvolatile electrical control of both photocurrent direction and
spin configurations. This work provides evaluation criteria and practical guidance for designing high-performance integrated spintronic–photovoltaic devices.
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All authors Yue Zhao, Fu Li, Vikrant Chaudhary, Hongbin Zhang, Gaoyang Gou, Niuzhuang Yang, Yue Hao, Wenyi Liu
Materials Science · Cross-listed from physics.chem-ph
From Full Dynamic to Pure Static: A Family of $GW$-Based Approximations
Pierre-François Loos and Johannes Tölle
We introduce a systematic hierarchy of one-body Green's function methods derived from the $GW$ approximation, constructed by progressively reducing the dynamical content of the self-energy. Starting from the fully dynamical Dyson formulation, we generate a family of approximations that interpolates between the standard $GW$ approximation to purely static effective single-particle
Hamiltonians. This framework enables a controlled investigation of the role of dynamical effects and particle-hole coupling in the description of ionization potentials. Within this unified formalism, the hole and particle branches can be selectively decoupled through downfolding strategies into reduced one-particle spaces. By benchmarking the different members of this hierarchy on molecular ionization energies, we assess their accuracy, numerical robustness, and algorithmic complexity. We demonstrate that consistently derived partially static schemes can yield reliable quasiparticle energies while significantly simplifying the underlying
eigenvalue problem. We further introduce a novel static Hermitian self-energy obtained as the static limit of this hierarchy. Despite its conceptually distinct origin, it produces results remarkably close to those of qs$GW$, thereby providing an alternative static route toward partial self-consistency.
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Materials Science · Cross-listed from cond-mat.mes-hall
Modern Approach to Orbital Hall Effect Based on Wannier Picture of Solids
Mirco Sastges, Insu Baek, Hojun Lee et al. (+3 more)
The orbital
Hall effect (OHE) and its key figure of merit, the orbital
Hall conductivity (OHC), are central to the emerging field of orbitronics. The OHC is conventionally computed via Kubo linear response theory, where the orbital angular momentum (OAM) operator is approximated through atom-centered projections that retain only local contributions, discarding physically important itinerant components. Here, we present a rigorous framework for the OAM operator grounded in the modern theory of orbital magnetization, formulated in a Wannier function basis. Critically, this naturally introduces a hierarchy of non-local contributions to the OAM operator. In turn, this gives rise to an additional non-Kubo contribution to the OHC of purely
geometric origin, absent in all atom-centered treatments. First-principles calculations across a diverse set of materials demonstrate that this term can constitute a significant fraction of the total OHC, with its omission leading to qualitatively incorrect predictions. Our framework provides a unified and numerically tractable approach to orbital transport and improves our understanding of the OAM in solids, allowing for a more precise estimation of various orbital effects in complex materials.
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All authors Mirco Sastges, Insu Baek, Hojun Lee, Hyun-Woo Lee, Yuriy Mokrousov, Dongwook Go
Materials Science
Rapid and Highly Efficient Synergistic Sonophotocatalytic Degradation of Methyl Orange with CuDoped LaFeO3 Perovskite Nanoparticles
Salma Elmouloua, M barek Amjoud, Daoud Mezzane et al. (+6 more)
The integration of sonocatalysis with photocatalysis offers a powerful strategy for advanced wastewater treatment by overcoming rapid charge carrier recombination in conventional photocatalytic systems. Although these processes are often treated separately due to their distinct mechanisms, their combination creates a highly efficient synergistic system. In this study, we investigate the sonophotocatalytic degradation of methyl orange (MO) using Cu-doped LaFeO3 perovskite nanoparticles. The Cu doped catalyst demonstrated excellent performance, achieving a degradation rate of 0.0455 min-1 and complete removal of MO within 120 minutes under combined ultrasonic and light irradiation. A strong synergistic effect was observed, with a synergy index of approximately 10, highlighting the enhanced interaction between sonocatalysis and photocatalysis. The catalyst also exhibited good stability and reusability, maintaining high efficiency over four consecutive cycles. Mechanistic studies using scavenger experiments revealed that hydroxyl radicals and photogenerated holes are the main reactive species responsible for degradation. A plausible reaction pathway is proposed based on these findings. Overall, Cu doped LaFeO3 shows superior sonophotocatalytic activity compared to the undoped material, demonstrating the potential of synergistic sonophotocatalytic processes for efficient pollutant removal.
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All authors Salma Elmouloua, M barek Amjoud, Daoud Mezzane, Manal Benyoussef, Jaafar Ghanbaja, Mohamed Goune, Mohamed Lahcini, Zdravko Kutnjak, Mimoun El Marssi
Materials Science · Cross-listed from physics.optics
Experimental Evidence of Thermal Capillary Waves Excitation on a Microsphere Surface
Abhishek Sureshkumar, Georges Perin, Julien Lapeyre et al. (+7 more)
Whispering-gallery-mode (WGM) microsphere resonators have emerged as a versatile platform across various photonic applications. Despite significant progress, their performance at short wavelengths is fundamentally limited by scattering-induced optical losses that restrict achievable quality factors (Q-factor). Although surface roughness has long been recognised as the leading cause of these losses, its physical origin has remained unclear, with current understanding attributing it to unavoidable fabrication imperfections. Here, we show that thermally excited capillary waves are the fundamental source of scattering losses in microsphere cavities. Using high-resolution atomic force microscopy (AFM) combined with rigorous statistical analysis, we quantitatively identify the characteristic signatures of frozen capillary fluctuations at the sub-nanometre level. The experimentally extracted roughness parameters show close agreement with theoretical predictions based on capillary wave theory. These findings fundamentally revise the prevailing interpretation of surface scattering losses and establish thermodynamic fluctuations, rather than fabrication defects, as the limiting roughness mechanism. By identifying frozen capillary waves as the limiting factor, this work opens new pathways for engineering ultra-high-Q microsphere resonators through fabrication management strategies, particularly for visible- and ultraviolet-photonic applications where scattering losses are most severe.
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All authors Abhishek Sureshkumar, Georges Perin, Julien Lapeyre, Rozenn Bernard, Kelig Terrien, Bertrand Dudoux, Adil Haboucha, Hélène Ollivier, Yannick Dumeige, Stéphane Trebaol
Materials Science
Odd-parity Magnetism from the Generalized Bloch Theorem
Mikkel Christian Larsen and Thomas Olsen
In the non-relativistic limit, helimagnetic order is always associated with odd-parity magnetism. That is, for single-particle states the expectation value of the electronic
spin is odd in
crystal momentum, which implies direct control of the
spin by means of electric fields. However, the theoretical description of helimagnets is hindered by the fact that the spiral pitch may require large super
cells or even be incommensurate with the
lattice. In the this letter we show that such issues may be remedied by use of the Generalized Bloch
theorem. It allows one to describe (by models or first principles) the system in terms of the primitive unit
cell, from which all relevant properties can be obtained by downfolding in reciprocal space. We exemplify the procedure using MnI$_2$ and NiI$_2$, which are known type II multiferroics having spiral order and the helimagnetic metal MnTe$_2$. We analyze how the magnitude of
spin splitting depends on orbital composition of bands, and we show that
spin splitting is maximized for states having large odd-orbital ($p$-type) character. It is straightforward to generalize the framework to handle response functions for helimagnets using only the primitive unit
cell and the present downfolding procedure thus strongly facilitate theoretical progress in the field.
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Materials Science · Cross-listed from physics.optics
Comparative performance of three optical biosensing platforms for SARS-CoV-2 antibodies detection in human serum
Agostino Occhicone, Alberto Sinibaldi, Peter Munzert et al. (+5 more)
This study presents a rigorous comparative analysis of two label-free optical biosensing platforms, Bloch surface wave (BSW) and microring resonator (MRR), for the detection of SARS-CoV-2 antibodies in human serum. To ensure direct comparability, a new BSW readout system was established alongside an existing MRR platform, allowing assays to be conducted under nearly identical experimental conditions. Both sensors were functionalized with various SARS-CoV-2 Spike and Nucleocapsid
protein variants to capture specific host antibodies. The results demonstrate that both platforms provide rapid, quantitative, and sensitive detection of anti-Spike and anti-Nucleocapsid antibodies without the need for secondary labels. Furthermore, the platforms show excellent agreement with longitudinal serology
benchmarks and high repeatability across different biochip batches. This work establishes both BSW and MRR technologies as powerful, low-cost candidates for next-generation clinical diagnostics and serological surveillance.
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All authors Agostino Occhicone, Alberto Sinibaldi, Peter Munzert, Jordan N. Butt, Ethan P. Luta, Diego M. Arévalo, Francesco Michelotti, Benjamin L. Miller
Materials Science · Cross-listed from cond-mat.str-el
Co-operating multiorbital and nonlocal correlations in bilayer nickelate
Evgeny A. Stepanov, Steffen Bötzel, Ilya M. Eremin et al. (+1 more)
The interplay of multiorbital physics and nonlocal self-energy effects is studied within an effective three-orbital model for the high-pressure normal state of superconducting
bilayer nickelate La$_3$Ni$_2$O$_7$. The model is solved within an advanced many-body framework capturing $k$-dependent correlations beyond dynamical mean-field theory. Different low-energy scenarios subtly depend on the strength of the interorbital interaction, either placing the notorious flat $\gamma$ quasiparticle band in the occupied part of the spectrum, or letting it cross the
Fermi level. In the latter case, intriguing
spin-polaron formation due to the scattering of electrons with paramagnon excitations takes place. This leads to bound states appearing as a shadow band with incoherent low-energy spectral weight below the
Fermi level. Our results uncover additional competing states that exist in
bilayer nickelates and could explain the controversy of recent angle-resolved photoemission experiments.
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All authors Evgeny A. Stepanov, Steffen Bötzel, Ilya M. Eremin, Frank Lechermann
Materials Science
Giant photostriction in lead-free ferroelectric stemming from photo-excited thermalized carriers
Gaëlle Vitali-Derrien, Oana Condurache, Antoine Ducournau et al. (+14 more)
Ferroelectrics are polar materials whose polarization can be switched by applying electric fields; they offer unique opportunities to develop performant photostrictive materials, i.e., materials that can deform under visible light illumination. Naturally devoid of inversion
symmetry, they exhibit original photogalvanic effects such as the Bulk Photovoltaic Effect, which relies on “hot” photoexcited carriers. It has long been thought that the electric field generated by this effect may couple to the natural piezoelectric abilities of ferroelectrics to provide large photoinduced deformations. However, due to competing effects, such as thermal dilatation, deformation potential, polarization, or depolarizing-field screening by thermalized carriers, it remains unclear which microscopic phenomena govern the photoinduced deformations in classical ferroelectric materials. Here, we demonstrate the largest photoinduced deformation measured in a ferroelectric thin film. Reaching 1 %, this
giant photostriction likely originates from the contribution of thermalized photoinduced carriers.
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All authors Gaëlle Vitali-Derrien, Oana Condurache, Antoine Ducournau, Pascale Gemeiner, Maxime Vallet, Nicolas Guiblin, Thomas Antoni, Sylvia Matzen, Pascal Ruello, Dagmar Chvostova, Tetyana Ostapchuk, Jirka Hlinka, Simon Hurand, Mouna Khiari, Houssny Bouyanfif, Charles Paillard, Pierre-Eymeric Janolin
Materials Science
Bulk versus interface nucleation of CO$_2$ hydrates from computer simulations
Joanna Grabowska, Samuel Blazquez, Carlos Vega et al. (+1 more)
Gas hydrates are of great relevance to both the oil industry and the environment. Understanding how these solid structures nucleate from aqueous solutions is essential to controlling their formation. Experimental studies have often suggested that hydrate nucleation originates at the interface between the aqueous phase and the guest-molecule reservoir. To assess this hypothesis, we perform molecular dynamics simulations of CO$_2$ hydrate nucleation. First, we place hydrate seeds at different positions relative to the interface and monitor their
evolution, finding that seeds embedded in the bulk are more likely to grow than those located near or at the interface. Second, we analyse spontaneous nucleation simulations with and without an interface. Our previous work showed that nucleation rates are indistinguishable in both systems, strongly indicating that the interface does not play a role. Here, trajectory analysis reveals that hydrates nucleate in regions of locally high CO$_2$ concentration, which arise spontaneously in the bulk and are not associated with the interface. Our results indicate that hydrate nucleation does not preferentially occur at the interface, at least at the at deep supercooling conditions explored in this work. Further work at higher temperatures, and considering alternative nucleation locations, is needed to reconcile experiments and simulations, and thereby reach a deep understanding of the mechanism of hydrate formation.
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All authors Joanna Grabowska, Samuel Blazquez, Carlos Vega, Eduardo Sanz
Materials Science
Switching magnetic spin-states using small magnetic fields in compositionally complex Sm(M7)O$_3$
R. K. Dokala, M. Geers, P. Nordblad et al. (+2 more)
High-
entropy perovskites (HEPs) offer a unique platform for exploring
magnetic phenomena arising from extreme B-site chemical disorder. In Sm(M7)O$_3$, where there are 7 cations in equal amounts at the B-site; M = Ti, Cr, Mn, Fe, Co, Ni, Cu), we observe long-range
antiferromagnetic ordering near 105 K accompanied by a small but robust excess
magnetic moment intrinsic to the chemically disordered
lattice. This uncompensated moment is evident from ZFC-FC irreversibility, shifts in the isothermal M(H) loops, and discrete remanent states identified through direct-current-demagnetization measurements. Remarkably, cooling fields as small as $\pm$ 20 Oe are sufficient to select the direction of the excess moment, and the chosen
magnetic state remains stable against applied fields up to 50 kOe. A low-temperature anomaly in the remanent magnetization further reveals a secondary contribution from the Sm$^{3+}$ sublattice, although the primary origin of the excess moment resides in the B-site AFM sublattice.
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All authors R. K. Dokala, M. Geers, P. Nordblad, R. Clulow, R. Mathieu
Materials Science
Equivariant Many-body Message Passing Interatomic Potentials for Magnetic Materials
Cheuk Hin Ho, Cas van der Oord, James P. Darby et al. (+11 more)
Magnetism governs key properties of materials used in energy, data storage, and spintronic technologies, yet its complex coupling to
lattice and electronic degrees of freedom challenges conventional first-principles approaches. We introduce an equivariant message-passing graph neural network that embeds atomic
magnetic moments as explicit degrees of freedom, enabling the learning of
magnetic interactions beyond collinear approximations. The model learns physically consistent and transferable representations of
magnetic behaviour and can incorporate
spin-orbit coupling, achieving near density-functional-theory accuracy with strong data efficiency across diverse
magnetic systems by fine-tuning from a pre-trained model. Applications to structural transformations, finite-temperature
magnetic phenomena, and materials screening for strongly
spin-orbit coupled materials demonstrate transferable
magnetic behaviour, establishing a practical foundation for data-driven, high-throughput discovery of complex
magnetic materials.
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All authors Cheuk Hin Ho, Cas van der Oord, James P. Darby, Theo Keane, Raz L. Benson, Cristian Rebolledo Espinoza, Rutvij Kulkarni, Elina Spinu, Michail Papanikolaou, Richard Tomsett, Robert M. Forrest, Jonathan J. Bean, Gábor Csányi, Christoph Ortner
Materials Science
Unveiling the Core of Materials Properties via SISSO and Sensitivity Analysis
Lucas Foppa and Matthias Scheffler
Interpretable AI can reveal physical principles governing intricate materials properties by uncovering explicit relationships between physical parameters and target properties. The sure-independence screening and sparsifying operator (SISSO) symbolic-regression approach identifies analytical expressions that correlate a target property with a small set of parameters, termed materials genes, selected from a large pool of candidates. However, multiple gene combinations can yield equally accurate SISSO models, with individual genes contributing with different weights. Here, we establish a derivative-based sensitivity analysis that resolves the non-uniqueness of symbolic-regression descriptions, enhances interpretability, thereby enabling deeper physical insight. This analysis reveals how distinct gene combinations encode equivalent information and identifies valence orbital radii,
nuclear charges, and their products as the key quantities governing the
equilibrium lattice constant of perovskites.
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Materials Science · Cross-listed from physics.comp-ph
Direction-aware topological descriptors for elastic stiffness tensor prediction in porous materials
Rafał Topolnicki, Michał Bogdan, Jakub Malinowski et al. (+3 more)
Classical topological descriptors used in topological data analysis (TDA) are invariant under permutations of spatial axes and therefore cannot represent the loading direction, which is essential for modeling anisotropic mechanical response. Here, this limitation is addressed by introducing a direction-aware TDA framework in which the loading axis is explicitly embedded into filtration functions used to compute both persistent homology and Euler characteristic profile descriptors. We apply this framework to predict the full elastic stiffness tensor of porous microstructures using non-directional as well as direction-aware descriptors of the structures as well as convolutional neural networks trained directly on the voxelized structure. We show that the performance of all those are comparable on the diagonal uniaxial, Poisson, and shear components. However for the twelve off-diagonal, normal shear coupling components - which govern elastic anisotropy and are the hardest to predict - only direction-aware
topology retains meaningful predictive power, with all baselines, non-directional descriptors and the CNN collapsing to near-chance accuracy. When used as inputs to gradient-boosted tree models, the proposed descriptors match or exceed the accuracy of the convolutional neural network specifically on these hardest-to-predict coupling terms, despite relying on a compact, physically interpretable representation that is orders of magnitude smaller than the raw voxel grid. Overall, the results establish direction-aware TDA as a practical route for linking porous microstructure to the full anisotropic elastic response, capturing coupling terms that conventional descriptors and end-to-end deep learning models fail to resolve.
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All authors Rafał Topolnicki, Michał Bogdan, Jakub Malinowski, Bartosz Naskręcki, Maciej Harańczyk, Paweł Dłotko
Materials Science
Oxophilic Silver-Based Nanoparticles with Low Pd-Au Loading for Ethanol and Glycerol Electrooxidation in Alkaline Media
Tuani Carla Gentil, Camilo Andrea Angelucci, Bruno Lemos Batista et al. (+5 more)
The electrocatalytic activity of oxophilic Ag nanoparticles, combined with small amounts of Pd and Au, was investigated for ethanol oxidation reactions (EOR) and glycerol oxidation reactions (GOR) in alkaline media. The EOR and GOR results revealed competitive current densities and less positive onset potentials for the AgPd/C and AgPdAu/C electrocatalysts, both containing 5 wt% Pd, compared to the commercial Pd/C catalyst, which has a significantly higher loading of the costly noble metal (20 wt%). In situ FTIR analyses during EOR confirmed that ethanol is initially adsorbed as acetylated species, which are subsequently oxidized to acetate ions, the main stable product in alkaline medium. However, the incorporation of Pd and Au into the Ag
matrix did not significantly alter the reaction mechanism. During GOR, the in situ FTIR studies demonstrated that catalyst composition influences the oxidation pathways: Pd-rich surfaces favor oxalate formation, while a significant presence of Ag promotes deeper oxidation (up to carbonate), with the AgPdAu ternary catalyst exhibiting intermediate behavior. One key benefit is the lower susceptibility of Ag to irreversible adsorption of reaction byproducts, which enhances electrocatalyst durability. Thus, surface segregation of Ag at high potentials can modify the catalytic surface reactivity, affecting both stability and efficiency.
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All authors Tuani Carla Gentil, Camilo Andrea Angelucci, Bruno Lemos Batista, Camila Neves Lange, Handro S. N. Lourenço, Mauro Coelho dos Santos, Vinicius Del Colle, Germano Tremiliosi-Filho
Materials Science
Emergence of Lissajous trajectories in skyrmion oscillator
Tamali Mukherjee and V Satya Narayana Murthy
Understanding the dynamics of current-driven skyrmion is essential for their practical applications. In this study, we apply an ac pulse (a) in x– direction, and (b) in both x– and y– directions through the free layer of a Co/Pt thin film and investigate the motion of the skyrmion. We show that the skyrmion follows the sinusoidal current pulse and behaves like an oscillator in the range of current amplitude 1 $\times$ 10$^{11}$ A/m$^2$ to 1 $\times$ 10$^{12}$ A/m$^2$ and frequency 5 $\times$ 10$^{8}$ rad/s to 1 $\times$ 10$^{10}$ rad/s. For current pulse of (A$_1$sin$\omega_1$t, A$_2$sin($\omega_2$t+$\phi$), 0), the skyrmion forms Lissajous figures in the x-y plane, same as observed in classical mechanics. The results are compared at T = 0 K and T $>$ 0 K to analyze the effect of temperature. As the skyrmion
Hall angle ($\theta_{SkH}$) and
stochastic thermal fluctuation ($\bm{F}^{Th}$) are functions of temperature, the skyrmion starts deviating from its path at T = 0 K with increasing temperature and eventually generates somewhat deformed Lissajous figures from ideal.
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Materials Science · Cross-listed from cond-mat.mes-hall
Optical Hall absorption sum rule and spectral compensation in time-reversal-breaking moiré and Hofstadter systems
Yixin Zhang and H. Huang
Optical spectroscopy provides a powerful, contact-free probe of topological
quantum states, yet exact constraints on antisymmetric
Hall absorption remain much less well developed than their longitudinal counterparts. Motivated by earlier
Hall-conductivity sum rules, we formulate the corresponding first-frequency-moment constraint for the antisymmetric optical conductivity, whose imaginary part governs chirality-dependent absorption. We then demonstrate this sum rule in two classes of time-reversal-breaking topological systems. For a zero-field moiré continuum model hosting topological bands, the moment vanishes exactly, implying that any low-frequency anomalous
Hall absorption must be compensated by higher-frequency spectral weight of the opposite sign. For a Hofstadter model under a uniform
magnetic field, the same moment takes a universal value fixed by the
magnetic flux density, independent of microscopic model details. By linking low- and high-frequency spectral contributions, this optical
Hall absorption sum rule provides a rigorous framework for quantifying circular dichroism constraints and diagnosing Landau-level mixing. Our results show how a known
Hall spectral constraint acquires new and experimentally relevant content in modern interacting topological materials.
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Materials Science
Tailoring the Optoelectronic, Photocatalytic, Thermoelectric and Thermodynamic Properties of Halides Li2InBiX6 (X = Cl, Br, I) for Energy Conversion: A DFT Study
Huda A. Alburaih, Sikander Azam, N. A. Noor et al. (+2 more)
Double perovskite halides are emerging as promising materials for a wide range of applications, particularly in renewable energy technologies such as
solar cell devices, thereby contributing to addressing global energy demands. In this work, the structural, electronic, optical, dielectric, thermoelectric, and photocatalytic properties of Li2InBiX6 (X = Cl, Br, I) halides are systematically investigated using density functional theory. The calculated formation energies confirm the thermodynamic stability of these compounds in the cubic phase. The studied materials exhibit semiconducting behavior with direct bandgaps of 1.7 eV, 1.3 eV, and 1.1 eV for Li2InBiCl6, Li2InBiBr6, and Li2InBiI6, respectively. The complex dielectric function is analyzed to explore their optical response, revealing strong absorption in the infrared and visible regions, indicating suitability for optoelectronic applications. Thermoelectric properties, including the Seebeck coefficient, electrical conductivity, and figure of merit (ZT), are evaluated over a temperature range of 30 to 800 K. The relatively small bandgaps contribute to enhanced thermoelectric performance, reflected in improved power factors. Furthermore, photocatalytic analysis indicates that Li2InBiX6 compounds are suitable candidates for water oxidation reactions within the pH range of 0 to 7. Overall, the combined thermoelectric and optical performance highlights these double perovskite halides as promising materials for future energy conversion applications.
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All authors Huda A. Alburaih, Sikander Azam, N. A. Noor, A. Laref, Sohail Mumtaz
Materials Science
Differentiable hybrid force fields support scalable autonomous electrolyte discovery
Xintian Wang, Junmin Chen, Zhuoying Zhu et al. (+1 more)
Autonomous electrolyte discovery demands a computational engine that satisfies a critical trilemma: it must be fast enough for high-throughput screening, accurate enough for quantitative property prediction, and calibratable enough for online refinement. Classical empirical force fields (FFs) are fast but rely on error cancellation, while standard machine learning interatomic potentials (MLIPs) are computationally expensive. In this Perspective, we highlight that differentiable hybrid FFs resolve this trilemma by fusing physically motivated functional forms with neural-network short-range corrections. Grounded in Energy Decomposition Analysis (EDA), state-of-the-art models such as PhyNEO-Electrolyte and ByteFF-Pol achieve zero-shot generalization to bulk phases, delivering throughputs on the order of tens of ns/day (up to $\sim$50 ns/day, depending on model complexity) for 10,000-atom systems. Crucially, their physical skeletons provide a well-conditioned parameter space for differentiable molecular dynamics (dMD). This enables a dual-calibration paradigm: bottom-up ab initio parameterization combined with top-down fine-tuning from macroscopic experimental observables. We propose that this architecture meets the requirements of a “ChemRobot-ready” digital twin by integrating physics-grounded simulation with experimentally calibratable refinement, thereby enabling closed-loop autonomous electrolyte discovery.
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All authors Xintian Wang, Junmin Chen, Zhuoying Zhu, Peichen Zhong
Materials Science
Alkaline-Earth Rare-Earth Fluoride Nanoparticle Superlattices for Ultrafast, Radiation Stable Scintillators
Parivash Moradifar, Tim Brandt van Driel, Masashi Fukuhara et al. (+9 more)
Radioluminescent nanostructures provide a pathway to the fabrication of next-generation scintillators with tunability in composition, size, and morphology, and spectral and temporal properties, as well as scalable processing. Here we create a 3D millimeter-scale solid-state scintillators from SrLuF Ce3+, Pr3+ (SrLuF) core-shell nanostructures, integrating nanoscale building blocks into self-assembled macroscopic
crystals. These scintillators exhibit single-digit nanosecond decay times, linear response, resistance to radiation-induced degradation, and optical emission yields within an order of magnitude of YAG Ce3+. We select a SrLuF host
lattice owing to its high effective atomic number, wide band gap, and low
phonon energy, which together support efficient 4f-5d radiative transitions from Ce3+ and Pr3+ activators while suppressing afterglow. We create a library of core-shell nanoscintillators with undoped SrLuF shells and cores spanning compositions from undoped SrLuF to fully doped SrCeF or SrPrF. Time-resolved and steady-state X-ray excited optical luminescence (XEOL) reveal broadband emission at 310 nm (Ce3+) and 335 nm (Pr3+) with biexponential decays in the sub-nanosecond (100-500 ps) and sub-15 ns (4-13 ns) regimes, demonstrating tunable radiative efficiency and ultrafast dynamics. Ensemble performance of the mm-scale superlattices is characterized under both continuous-wave and femtosecond high-intensity excitation, revealing high light yield, linear response, and radiation hardness under extreme irradiation of ultrafast 50fs X-ray pulses up to 5mJ per mm2 corresponding to a peak intensity of 1013 W per cm2. Together, these results establish a design framework for stable, bright, and tunable scintillation platforms with applications in precision health, space exploration and hard X-ray imaging at next-generation free-electron
laser facilities.
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All authors Parivash Moradifar, Tim Brandt van Driel, Masashi Fukuhara, Cindy Shi, Ariel Stiber, Federico Moretti, Qingyuan Fan, Diana Jeong, Aaron M. Lindenberg, Garry Chinn, Craig S. Levin, Jennifer A. Dionne
Materials Science · Cross-listed from cond-mat.str-el
Directional Criticality and Higher-Order Flatness: Designing Van Hove Singularities in Three Dimensions
Hua-Yu Li, Hengxin Tan, Hao-Yu Zhu et al. (+2 more)
Van Hove singularities (VHSs) play a pivotal role in driving correlated electronic phenomena. Traditional classifications focus only on critical points where the band gradient vanishes in all directions. Here we establish a unified classification of VHSs in three-dimensional systems, characterized by the number of vanishing gradient components and Hessian
eigenvalues: ordinary ($M$-type), higher-order ($T_1$, $T_2$, $T_3$), noncritical ordinary ($N_0$, $N_1$, $N_2$), and noncritical higher-order ($S_1$, $S_2$) types. Noncritical VHSs exhibit directional quenching: the gradient vanishes in a two-dimensional subspace while remaining finite along the orthogonal direction, yielding finite density-of-states enhancements with distinct energy dependencies. Using an $s$-orbital tight-binding model on the pyrochlore
lattice with
spin-orbit coupling, we demonstrate that all singularity classes emerge at distinct high-
symmetry points through controlled tuning of the hopping ratio. This work establishes directional criticality and higher-order flatness as design principles for tailoring density-of-states enhancements in three-dimensional
quantum materials.
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All authors Hua-Yu Li, Hengxin Tan, Hao-Yu Zhu, Hong-Kuan Yuan, Min-Quan Kuang
Materials Science · Cross-listed from physics.bio-ph
Biogenic bubbles enable microbial escape from physical confinement
Babak Vajdi Hokmabad, Thomas Appleford, Hao Nghi Luu et al. (+3 more)
Immotile microbes inhabit nearly every environment on Earth, from soils and sediments to food
matrices – yet how they disperse through these physically confining environments is poorly understood. Here, we show that immotile microbial colonies confined in a model transparent yield-stress
matrix can achieve long-range dispersal by harnessing their own metabolism. Using yeast as a model organism, we find that fermentation drives dissolved CO$_2$ to supersaturation, nucleating biogenic bubbles that grow, yield the
matrix, and rise, hydrodynamically entraining
cells vertically in their wake. Sequential bubble nucleation sculpts persistent columnar colonies extending far beyond what growth alone permits. Multiple colonies interact via their fermentation byproducts, merging and mixing genetically as they collectively sculpt self-sustaining conduit networks. Our findings reveal a third mode of microbial dispersal, distinct from the canonical mechanisms of motility and growth, with implications for ecology, environmental science, and biotechnology. More broadly, they exemplify a previously unrecognized class of active behavior – Metabolically Driven Active Matter – in which metabolic byproducts reshape the physical landscape of confinement to drive population-scale motion.
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All authors Babak Vajdi Hokmabad, Thomas Appleford, Hao Nghi Luu, Meera Ramaswamy, Maziyar Jalaal, Sujit S. Datta
Materials Science
Symmetry-guided and AI-accelerated design of intercalated transition metal dichalcogenides for antiferromagnetic spintronics
Yu Pang, Yue Gu, Runsheng Zhong et al. (+4 more)
The advancement of
antiferromagnetic spintronics depends on
quantum materials with target
symmetry-dictated functionalities, however, their systematic discovery is hindered by the immense configurational complexity of the available material space. Here, we introduce a
symmetry-guided, AI-accelerated framework incorporating graph neural networks with high generalization ability to overcome this bottleneck. Based on fully intercalated transition metal dichalcogenides (iTMDs) and using only 200 relaxed partially intercalated structures for transfer learning, our model effectively explores more than 100,000 partially intercalated configurations and identifies 35 altermagnetic and 20 $T\tau$-
antiferromagnetic ground-state candidates. Interestingly, we show that tuning
spin-group
symmetry through intercalant arrangement or
magnetic ordering realizes a series of d-wave altermagnets in these hexagonal systems with high
spin-charge conversion efficiency. Furthermore, we reveal plentiful $T\tau$-antiferromagnets enabling efficient Néel
spin-orbit torque switching, driven by
giant $T$-odd
spin Edelstein susceptibilities. These results establish iTMDs as a versatile platform for spintronics and provide a general strategy for the accelerated design of
symmetry-enforced
quantum materials.
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All authors Yu Pang, Yue Gu, Runsheng Zhong, Liyang Zou, Xiaobin Chen, Xiaolong Zou, Wenhui Duan