Materials Science · Cross-listed from cs.LG
SHA-256 Infused Embedding-Driven Generative Modeling of High-Energy Molecules in Low-Data Regimes
Siddharth Verma and Alankar Alankar
High-energy materials (HEMs) are critical for propulsion and defense domains, yet their discovery remains constrained by experimental data and restricted access to testing facilities. This work presents a novel approach toward high-energy molecules by combining Long Short-Term
Memory (LSTM) networks for molecular generation and Attentive Graph Neural Networks (GNN) for property predictions. We propose a transformative
embedding space construction strategy that integrates fixed SHA-256
embeddings with partially trainable representations. Unlike conventional regularization techniques, this changes the representational basis itself, reshaping the molecular input space before learning begins. Without recourse to pretraining, the generator achieves 67.5% validity and 37.5% novelty. The generated library exhibits a mean Tanimoto coefficient of 0.214 relative to training set signifying the ability of framework to generate a diverse chemical space. We identified 37 new super explosives higher than 9 km/s predicted detonation velocity.
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Materials Science
Preliminary Demonstration of Diamond-GaN pn Diodes via Grafting
Jie Zhou, Yi Lu, Chenyu Wang et al. (+18 more)
Ultrawide bandgap (UWBG)
semiconductors exhibit exceptional electrical and thermal properties, offering strong potential for high power and high frequency electronics. However, efficient doping in UWBG materials is typically limited to either n type or p type, constraining their application to unipolar devices. The realization of pn junctions through heterogeneous integration of complementary UWBG or WBG
semiconductors is hindered by
lattice mismatch and thermal expansion differences. Here, we report the preliminary demonstration of diamond GaN heterojunction pn diodes fabricated via grafting. A single crystalline p plus diamond nanomembrane was integrated onto an epitaxially grown c plane n plus GaN substrate with an ultrathin ALD Al2O3 interlayer. The resulting diodes exhibit an ideality factor of 1.55 and a rectification ratio of over 1e4. Structural and interfacial properties were examined by AFM, XRD, Raman, and STEM, providing critical insights to guide further optimization of diamond GaN pn heterojunction devices.
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All authors Jie Zhou, Yi Lu, Chenyu Wang, Luke Suter, Aaron Hardy, Tien Khee Ng, Kai Sun, Yifu Guo, Yang Liu, Tsung-Han Tsai, Xuanyu Zhou, Connor S Bailey, Michael Eller, Stephanie Liu, Zetian Mi, Boon S. Ooi, Matthias Muehle, Katherine Fountaine, Vincent Gambin, Jung-Hun Seo, Zhenqiang Ma
Materials Science
Trichome entanglement enhances damage tolerance in microstructured biocomposites
Israel Kellersztein, Mathieu Desgranges and Chiara Daraio
Achieving damage tolerance in composite materials remains a central challenge in materials science. Conventional strategies often rely on filler incorporation or chemical modification, which can limit energy dissipation and constrain structural stability. Here, we leverage the unique morphology of Spirulina trichomes to investigate a reinforcement mechanism based on physical filament
entanglement. By comparing helical trichomes with their morphologically straightened counterparts, we isolate filament geometry as the key parameter governing mechanical performance. Trichome-based suspensions exhibit enhanced viscoelastic response and a threefold increase in yield stress. When processed via extrusion-based 3D printing using hydroxyethyl cellulose (HEC) as a
matrix, entangled trichomes yield a 290% improvement in bending strength and a 15-fold enhancement in work of fracture. Fracture surface analysis reveals a transition from interfacial debonding and pull-out (in filaments) to crack propagation through the entangled network, indicating structure-mediated toughening. These findings establish trichome
entanglement as a scalable, physically driven mechanism for enhancing damage tolerance through microstructural architecture.
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Materials Science · Cross-listed from cond-mat.mes-hall
Magneto-optical spectroscopy based on pump-probe strobe light
Shihao Zhou, Yujie Zhu, Chunli Tang et al. (+12 more)
We demonstrate a pump-probe strobe light spectroscopy for sensitive detection of magneto-optical dynamics in the context of hybrid magnonics. The technique uses a combinatorial microwave-optical pump-probe scheme, leveraging both the high-energy resolution of microwaves and the high-efficiency detection using optical
photons. In contrast to conventional stroboscopy using a continuous-wave light, we apply microwave and optical pulses with varying pulse widths, and demonstrate magnetooptical detection of magnetization dynamics in Y3Fe5O12 films. The detected magneto-optical signals strongly depend on the characteristics of both the microwave and the optical pulses as well as their relative time delays. We show that good magneto-optical sensitivity and coherent stroboscopic character are maintained even at a microwave pump pulse of 1.5 ns and an optical probe pulse of 80 ps, under a 7 megahertz clock rate, corresponding to a pump-probe footprint of ~1% in one detection cycle. Our results show that time-dependent strobe light measurement of magnetization dynamics can be achieved in the gigahertz frequency range under a pump-probe detection scheme.
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All authors Shihao Zhou, Yujie Zhu, Chunli Tang, Rui Sun, Junming Wu, Yuzan Xiong, Ingrid E. Russell, Yi Li, Dali Sun, Frank Tsui, Binbin Yang, Valentine Novosad, Jia-Mian Hu, Wencan Jin, Wei Zhang
Materials Science · Cross-listed from astro-ph.EP
The Fate of Hydrogen and Helium: From Planetary Embryos to Earth- and Neptune-like Worlds
Akash Gupta, Haiyang Luo, Jie Deng et al. (+1 more)
Hydrogen, helium, silicates, and iron are key building blocks of rocky and gas-rich
planets, yet their chemical interactions remain poorly constrained. Using first-principles molecular dynamics and thermodynamic integration, we quantify hydrogen and helium partitioning between molten silicate mantles and metallic cores for Earth-to-Neptune-mass
planets. Hydrogen becomes strongly siderophilic above $\sim$25 GPa but weakens beyond $\sim$200 GPa, whereas helium remains lithophilic yet increasingly soluble in metal with pressure. Incorporating these trends into coupled structure-chemistry models suggests that majority of hydrogen and helium reside in planetary interiors, not atmospheres, with abundances strongly depending on
planet mass. Such volatile exchange may influence the redox states of secondary atmospheres, longevity of
primordial envelopes, predicted CHNOPS abundances, and emergence of helium-enriched atmospheres, while He 1083 nm and H Lyman-$\alpha$ lines provide potential probes of atmosphere-interior exchange. These findings link atomic-scale interactions to planetary-scale observables, providing new constraints on the origins of Earth-to-Neptune-sized worlds.
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All authors Akash Gupta, Haiyang Luo, Jie Deng, Adam Burrows
Materials Science
Stabilisation of hBN/SiC Heterostructures with Vacancies and Transition-Metal Atoms
Arsalan Hashemi, Nima Ghafari Cherati, Sadegh Ghaderzadeh et al. (+3 more)
When two-dimensional atomic layers of different materials are brought into close proximity to form van der Waals (vdW)
heterostructures, interactions between adjacent layers significantly influence their physicochemical properties. These effects seem particularly pronounced when the interface exhibits local order and near-perfect structural
alignment, leading to the emergence of Moiré patterns. Using
quantum mechanical density functional theory calculations, we propose a prototypical
bilayer heterostructure composed of hexagonal boron nitride (hBN) and silicon carbide (SiC), characterized by a
lattice mismatch of 18.77% between their primitive unit
cells. We find that the removal of boron atoms from specific
lattice sites can convert the interlayer interaction from weak vdW coupling to robust localized silicon-nitrogen covalent bonding. Motivated by this, we study the binding of transition-metal adatoms and formulate design guidelines to enhance surface reactivity, thereby enabling the controlled isolation of single-metal atoms. Our machine-learning-assisted molecular dynamics simulations confirm both dynamical stability and metal anchoring feasibility at finite temperatures. Our results suggest the hBN/SiC
heterostructure as a versatile platform for atomically precise transition-metal functionalization, having potential for next-generation catalytic energy-conversion technologies.
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All authors Arsalan Hashemi, Nima Ghafari Cherati, Sadegh Ghaderzadeh, Yanzhou Wang, Mahdi Ghorbani-Asl, Tapio Ala-Nissila
Materials Science · Cross-listed from quant-ph
Classically Prepared, Quantumly Evolved: Hybrid Algorithm for Molecular Spectra
Alessandro Santini, Stefano Barison and Filippo Vicentini
We introduce a hybrid classical-
quantum algorithm to compute dynamical correlation functions and excitation spectra in many-body
quantum systems, with a focus on molecular systems. The method combines classical preparation of a perturbed ground state with short-time
quantum evolution of product states sampled from it. The resulting
quantum samples define an effective subspace of the
Hilbert space, onto which the
Hamiltonian is projected to enable efficient classical simulation of long-time dynamics. This subspace-based approach achieves high-resolution spectral reconstruction using shallow
circuits and few samples.
Benchmarks on molecular systems show excellent agreement with exact diagonalization and demonstrate access to dynamical timescales beyond the reach of purely classical methods, highlighting its suitability for near-term and early fault-tolerant
quantum hardware.
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Materials Science
Improved operating voltage in InGaN-capped AlGaN-based DUV LEDs on bulk AlN substrates
H-W S. Huang, S. Agrawal, D. Bhattacharya et al. (+2 more)
Better wall plug efficiency of deep-ultraviolet light emitting diodes (DUV-LEDs) requires simultaneous low resistivity p-type and n-type contacts, which is a challenging problem. In this study, the co-optimization of p-InGaN and n- AlGaN contacts for DUV LEDs are investigated. We find that using a thin 7%InGaN cap is effective in achieving ohmic p-contacts with specific contact resistivity of 3.10x10^{-5} Ohm.cm^2. Upon monolithic integration of p- and n- contacts for DUV LEDs, we find that the high temperature annealing of 800C required for the formation of low resistance contacts to n-AlGaN severely degrades the p-InGaN layer, thereby reducing the hole concentration and increasing the specific contact resistivity to 9.72x10^{-4} Ohm.cm^2. Depositing a SiO2 cap by
plasma-enhanced atomic layer deposition (PE-ALD) prior to high temperature n-contact annealing restores the low p-contact resistivity, enabling simultaneous low-resistance p- and n-contacts. DUV-LEDs emitting at 268 nm fabricated with the SiO2 capping technique exhibit a 3.5 V reduction in operating voltage at a current level of 400 A/cm^2 and a decrease in differential ON-resistance from 6.4 mOhm.cm^2 to 4.5 mOhm.cm^2. This study highlights a scalable route to high-performance, high-Al-content bipolar AlGaN devices.
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All authors H-W S. Huang, S. Agrawal, D. Bhattacharya, H.G. Xing, D. Jena
Materials Science
Molecular simulations of Perovskites CsXI3 (X = Pb,Sn) Using Machine-Learning Interatomic Potentials
Atefe Ebrahimi, Franco Pellegrini and Stefano De Gironcoli
Cesium based halide perovskites, such as CsPbI3 and CsSnI3, have emerged as exceptional candidates for next generation photovoltaic and optoelectronic technologies, but their practical application is limited by temperature dependent phase transitions and structural instabilities. Here, we develop machine learning interatomic potentials within the LATTE framework to simulate these materials with near experimental accuracy at a fraction of the computational cost compared to previous computational studies. Our molecular dynamics simulations based on the trained MLIPs reproduce energies and forces across multiple phases, enabling large scale simulations that capture cubic tetragonal orthorhombic transitions,
lattice parameters, and octahedral tilting with unprecedented resolution. We find that Pb based perovskites exhibit larger octahedral tilts and higher phase transition temperatures than Sn based analogues, reflecting stronger bonding and enhanced structural stability, whereas Sn based perovskites display reduced tilts and lower barriers, suggesting tunability through compositional or interface engineering. Beyond these systems, our work demonstrates that MLIPs can bridge first principles accuracy with simulation efficiency, providing a robust framework for exploring phase stability, anharmonicity, and rational design in next generation halide perovskites.
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Materials Science · Cross-listed from physics.optics
Extracting Spectral Diffusion in Two-Dimensional Coherent Spectra via the Projection Slice Theorem
Cesar Perez and Steven Cundiff
A robust and streamlined method is presented for efficiently extracting spectral
diffusion from two-dimensional coherent spectra by employing the projection-slice
theorem. The method is based on the optical Bloch equations for a single resonance that include a Frequency-Frequency Correlation Function (FFCF) in the time domain. Through the projection slice
theorem (PST), analytical formulation of the diagonal and cross-diagonal projections of time-domain two-dimensional spectra are calculated that include the FFCF for arbitrary inhomogeneity. The time-domain projections are
Fourier transformed to provide frequency domain slices that can be fit to slices of experimental spectra. Experimental data is used to validate our lineshape analysis and confirm the need for the inclusion of the FFCF for
quantum wells that experience spectral
diffusion.
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Materials Science · Cross-listed from cond-mat.mes-hall
Bonding Character as a Descriptor for Huang-Rhys Factors in Optically Active Defects
Fatimah Habis and Yuanxi Wang
The electron
phonon coupling of a defect characterized by its Huang Rhys (HR) factor is a crucial metric determining its excited-state dynamics, relevant to defect applications as
qubits and
quantum emitters. However, HR factors remain challenging to calculate from first principles, complicated by convergence issues in excited-state relaxation and time consuming
phonon calculations. Even when calculated, HR factors lack a rational design principle. Here we show that an orbital-based descriptor can be used to rationalize and efficiently estimate HR factors. Combining this descriptor with a ground state deformation technique allows circumventing both excited state relaxation and full
phonon calculations. Specifically, our descriptor for HR factors is constructed using bonding character differences obtained from ground state density functional theory, measured using
crystal orbital Hamilton populations. We demonstrate this descriptor for prototypical hBN defects and the diamond NV center. This orbital-based descriptor can be potentially used in high throughput computational screening to identify ideal candidates of
spin qubits and SPEs.
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Materials Science
Flat bands in ultra-wide gap two-dimensional germanium dioxide
Rafael Franco Ribeiro Reis, Gabriel Elyas Gama Araujo, Danilo Kuritza et al. (+3 more)
We employ first principles density-functional theory (DFT) and the Bethe-Salpeter equation (BSE) in the framework of tight-binding based maximally localized Wannier functions (MLWF-TB) model to investigate the electronic and optical properties of free-standing two-dimensional (2D) germanium dioxide phases. All investigated 2D GeO2 polymorphs exhibit ultra-wide band gaps and strong excitonic effects, with flat O-p-derived valence bands tunable under strain. These features allow the design of flat band materials with ultra large electronic gaps in low-dimensional systems, making these materials promising for devices operation at higher voltages and temperatures than conventional
semiconductor materials.
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All authors Rafael Franco Ribeiro Reis, Gabriel Elyas Gama Araujo, Danilo Kuritza, Alexandre Cavalheiro Dias, Andreia Luisa da Rosa, Renato Borges Pontes
Materials Science
Comparative analysis of the lubrication performance of functionalized copolymers interacting with silicon, cobalt, and silver doped diamond-like carbon
Takeru Omiya, Enrico Pedretti, Pooja Sharma et al. (+5 more)
This study examines the tribological behavior of diamond-like carbon (DLC) coatings doped with silicon (Si), cobalt (Co), or silver (Ag) in the presence of an amine-functionalized block copolymer lubricant. Under boundary lubrication, Si-doped DLC (Si-DLC) exhibited the lowest coefficient of friction ($\approx$0.045) and nearly 45% lower wear than undoped DLC. Co-DLC showed moderate improvement, while Ag-DLC provided no significant benefit. Cross-sectional FIB-TEM revealed thin tribofilms, 12-17 nm in thickness, on Si- and Co-doped surfaces. As reported for Si-DLC, these films incorporate copolymer-derived fragments, suggesting a similar composition for Co-DLC. These results indicate that dopant-
polymer interactions are key to the development of self-organized boundary layers. To gain atomic-level insight, first-principles calculations were carried out on the adsorption of the dimethylaminoethyl methacrylate (DMAEMA) unit, the copolymer's functional group. The calculated adsorption energies were $-$2.27 to $-$0.57 eV for Si-DLC, $-$1.73 to $-$1.49 eV for Co(0001), and $-$1.21 to $-$1.08 eV for Ag(111). The order of stability (Si $>$ Co $>$ Ag) was consistent with the experimental tribological ranking. Chemical bonding dominated for Si-DLC, while Ag showed mainly weak physisorption. Simulated pull-off forces further reflected this hierarchy, with N-Si bonds requiring about twice the force of N-Co and nearly five times that of N-Ag. The correspondence between adsorption strength and tribological response highlights the decisive role of dopant species in tribofilm formation. These findings provide guidance for designing durable low-friction surfaces in applications such as electric drivetrains and precision mechanical systems.
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All authors Takeru Omiya, Enrico Pedretti, Pooja Sharma, Albano Cavaleiro, Arménio C. Serra, Jorge F. J. Coelho, Maria Clelia Righi, Fábio Ferreira
Materials Science · Cross-listed from cond-mat.supr-con
Enhanced Superconductivity in 2H-TaS2 Devices Through in-situ Molecular Intercalation
Jose M. Pereira, Daniel Tezze, Beatriz Martín-García et al. (+4 more)
The intercalation of guest species into the gap of van der Waals materials often leads to the emergence of intriguing phenomena, such as superconductivity. While intercalation-induced superconductivity has been reported in several bulk
crystals, reaching a zero-resistance state in flakes remains challenging. Here, we show a simple method for enhancing the superconducting transition in tens-of-nm thick 2H-TaS2
crystals contacted by gold electrodes through in-situ intercalation. Our approach enables measuring the electrical characteristics of the same flake before and after intercalation, permitting us to precisely identify the effect of the guest species on the TaS2 transport properties. We find that the intercalation of amylamine molecules into TaS2 flakes causes a suppression of the charge density wave and an increase in the superconducting transition, with an onset temperature above 3 K. Additionally, we show that a fully developed zero-resistance state can be achieved in flakes by engineering the conditions of the chemical intercalation. Our findings pave the way for the integration of chemically tailored intercalation compounds in scalable
quantum technologies.
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All authors Jose M. Pereira, Daniel Tezze, Beatriz Martín-García, Fèlix Casanova, Maider Ormaza, Luis E. Hueso, Marco Gobbi
Materials Science
Tunable magnetism in 2D organic-ion-intercalated MnPS3 via molecule-dependent vacancy generation
Daniel Tezze, Jose M. Pereira, Dogukan Tutar et al. (+12 more)
The
magnetic properties of van der Waals materials are profoundly influenced by structural defects. The layered antiferromagnet MnPS3 offers a unique opportunity to explore defect-related magnetism, as Mn2+ vacancies can be generated by the intercalation of specific guest molecules. However, the effectiveness of this process in atomically thin flakes and the extent of the
magnetic tunability remain unclear. Here, we show that the
magnetic properties of MnPS3 can be tailored through the intercalation of different guest molecules. Notably, the insertion of four alkylammonium ions introduces different populations of Mn2+ vacancies, leading to a transition from the pristine
antiferromagnetic state to more complex
magnetic textures, including a ferrimagnetic state displaying a
magnetic saturation of 1 uB/atom. Moreover, we show that the intercalation of few-nm-thick flakes also leads to the emergence of a ferrimagnetic response. This in-flake intercalation, which can be monitored in real time using optical microscopy, can be interrupted before completion, generating lateral
heterostructures between pristine and intercalated areas. This approach opens the way to the use of partial intercalation to define regions with distinct
magnetic properties within a single flake.
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All authors Daniel Tezze, Jose M. Pereira, Dogukan Tutar, Maria Ramos, Jakub Regner, Pierluigi Gargiani, Frederik Schiller, Felix Casanova, Angel Alegria, Beatriz Martin-Garcia, Hasan Sahin, Zdenek Sofer, Maider Ormaza, Luis Hueso, Marco Gobbi
Materials Science
Evolution of electronic and magnetic properties in Mn- and Co-alloyed ferromagnetic kagome metal Fe3Sn2
Prajwal M. Laxmeesha, Rajesh Dutta, Rajeev Kumar Rai et al. (+14 more)
Kagome metals are an intriguing class of
quantum materials as the presence of both flat bands and Dirac points provides access to functional properties present in strongly correlated and topological materials. To fully harness these electronic features, the ability to tune the
Fermi level relative to the band positions is needed. Here we explore the structural, electronic and
magnetic impacts of substitutional alloying within
ferromagnetic kagome metal Fe3Sn2 in thin films grown by molecular beam epitaxy. Transition metals Mn and Co are chosen as substitutes for Fe to reduce or increase the d-band electron count, thereby moving the
Fermi level accordingly. We find that Co is not incorporated into the Fe3Sn2 structure but instead results in a two-phase Fe-Co and (Fe,Co)Sn composite. In contrast, Fe3-xMnxSn2 films are realized with x up to 1.0, retaining crystalline quality comparable to the parent phase. The incorporation of Mn repositions the flat bands relative to the
Fermi level in a manner consistent with hole-doping, as revealed by hard x-ray photoemission and density functional theory. The Fe3-xMnxSn2 films retain room temperature ferromagnetism, with x-ray
magnetic circular dichroism measurements confirming that the Fe and Mn moments are ferromagnetically aligned. The ability to hole-dope this
magnetic kagome metal provides a platform for tuning properties such as anomalous
Hall and Nernst responses.
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All authors Prajwal M. Laxmeesha, Rajesh Dutta, Rajeev Kumar Rai, Sharup Sheikh, Michael F. DiScala, Uditha M. Jayathilake, Alexander Velič, Tarush Tandon, Tessa D. Tucker, Christoph Klewe, Haile Ambaye, Timothy Charlton, Tien-Lin Lee, Eric A. Stach, Kemp W. Plumb, Alexander X. Gray, Steven J. May
Materials Science
Unsupervised Machine-Learning Pipeline for Data-Driven Defect Detection and Characterisation: Application to Displacement Cascades
Samuel Del Fré, Andrée de Backer, Christophe Domain et al. (+2 more)
Neutron irradiation produces, within a few picoseconds, displacement cascades that are sequences of atomic collisions generating point and extended defects which subsequently affects the long-term
evolution of materials. The diversity of these defects, characterized morphologically and statistically, defines what is called the "primary damage". In this work, we present a fully unsupervised machine learning (ML) workflow that detects and classifies these defects directly from molecular dynamics data. Local environments are encoded by the Smooth Overlap of Atomic Positions (SOAP) vector, anomalous atoms are isolated with autoencoder neural networks (AE), embedded with Uniform
Manifold Approximation and Projection (UMAP) and clustered using Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN). Applied to 80 keV displacement cascades in Ni, Fe$_7$0Ni$_{10}$Cr$_{20}$, and Zr, the AE successfully identify the small fraction of outlier atoms that participate in defect formation. HDBSCAN then partitions the UMAP latent space of AE-flagged SOAP descriptors into well defined groups representing vacancy- and interstitial-dominated regions and, within each, separates small from large aggregates, assigning 99.7 % of outliers to compact physical motifs. A signed cluster-identification score confirms this separation, and cluster size scales with net defect counts (R2 > 0.89). Statistical cross analyses between the ML outlier map and several conventional detectors (centrosymmetry, dislocation extraction, etc.) reveal strong overlap and complementary coverage, all achieved without template or threshold tuning. This ML workflow thus provides an efficient tool for the quantitative mapping of structural anomalies in materials, particularly those arising from irradiation damage in displacement cascades.
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All authors Samuel Del Fré, Andrée de Backer, Christophe Domain, Ludovic Thuinet, Charlotte S. Becquart
Materials Science
Strain Engineering of van Hove Singularity and Coupled Itinerant Ferromagnetism in Quasi-2D Oxide Superlattices
Seung Gyo Jeong, Minjae Kim, Jin Young Oh et al. (+12 more)
Engineering van Hove singularities (vHss) near the
Fermi level, if feasible, offers a powerful route to control exotic
quantum phases in electronic and
magnetic behaviors. However, conventional approaches, which rely primarily on chemical and electrical doping, focus mainly on local electrical or optical measurements, limiting their applicability to coupled functionalities. In this study, a vHs-induced
insulator-metal transition coupled with a
ferromagnetic phase transition was empirically achieved in atomically designed quasi-2D SrRuO3 (SRO) superlattices via epitaxial strain engineering, which has not been observed in conventional 3D SRO systems. Theoretical calculations revealed that epitaxial strain effectively modulates the strength and energy positions of vHs of specific Ru orbitals, driving correlated phase transitions in the electronic and
magnetic ground states. X-ray absorption spectroscopy confirmed the anisotropic electronic structure of quasi-2D SRO modulated by epitaxial strain. Magneto-optic Kerr effect and electrical transport measurements demonstrated modulated
magnetic and electronic phases. Furthermore, magneto-electrical measurements detected significant anomalous
Hall effect signals and
ferromagnetic magnetoresistance, indicating the presence of magnetically coupled charge carriers in the 2D metallic regime. This study establishes strain engineering as a promising platform for tuning vHss and resultant itinerant ferromagnetism of low-dimensional correlated
quantum systems.
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All authors Seung Gyo Jeong, Minjae Kim, Jin Young Oh, Youngeun Ham, In Hyeok Choi, Seong Won Cho, Jihyun Kim, Huimin Jeong, Byungmin Sohn, Tuson Park, Suyoun Lee, Jong Seok Lee, Deok-Yong Cho, Bongjae Kim, Woo Seok Choi
Materials Science · Cross-listed from cond-mat.dis-nn
Deep-Learning-Empowered Programmable Topolectrical Circuits
Hao Jia, Shanglin Yang, Jiajun He et al. (+9 more)
Topolectrical
circuits provide a versatile platform for exploring and simulating modern physical models. However, existing approaches suffer from incomplete programmability and ineffective feature prediction and control mechanisms, hindering the investigation of physical phenomena on an integrated platform and limiting their translation into practical applications. Here, we present a deep learning empowered programmable topolectrical
circuits (DLPTCs) platform for physical modeling and analysis. By integrating fully independent, continuous tuning of both on site and off site terms of the
lattice Hamiltonian, physics graph informed inverse state design, and immediate hardware verification, our system bridges the gap between theoretical modeling and practical realization. Through flexible control and adiabatic path engineering, we experimentally observe the boundary states without global
symmetry in higher order topological systems, their adiabatic phase transitions, and the flat band like characteristic corresponding to Landau levels in the
circuit. Incorporating a physics graph informed mechanism with a generative AI model for physics exploration, we realize arbitrary, position controllable on board Anderson localization, surpassing conventional random localization. Utilizing this unique capability with high fidelity hardware implementation, we further demonstrate a compelling cryptographic application: hash based probabilistic information encryption by leveraging Anderson localization with extensive disorder configurations, enabling secure delivery of full ASCII messages.
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All authors Hao Jia, Shanglin Yang, Jiajun He, Shuo Liu, Haoxiang Chen, Ce Shang, Shaojie Ma, Peng Han, Ching Hua Lee, Zhen Gao, Yun Lai, Tie Jun Cui
Materials Science
Noise Estimation and Suppression in Quantitative EMCD Measurements
Hitoshi Makino, Bernd Rellinghaus, Sebastian Schneider et al. (+2 more)
Quantitative electron
magnetic circular dichroism (EMCD) in transmission electron microscopy (TEM) enables the measurement of
magnetic moments with elemental and atomic site sensitivity, but its practical application is fundamentally limited by noise. This study presents a comprehensive methodology for noise estimation and suppression in EMCD measurements, demonstrated on Ti-doped barium hexaferrite lamellae. By employing a classical three-beam geometry and long-term acquisition of electron energy-loss spectra, we systematically analyze the signal-to-noise ratio (SNR) across individual energy channels using bootstrap statistics. A robust energy
alignment procedure based on the neighboring Ba-M4,5 edges with an adequate energy upsampling is introduced to minimize systematic errors from energy misalignment. The impact of detector noise, particularly from CMOS-based EELS cameras, is evaluated through variance-to-mean analysis and described by the noise amplification coefficients, revealing that detector-amplified shot noise is the dominant noise source. We recommend a stricter SNR threshold for reliable EMCD detection and quantification, ensuring that critical spectral features such as the Fe-L2,3 peaks meet the requirements for quantitative analysis. The approach also provides a framework for determining the minimum electron dose necessary for valid measurements and can be generalized to scintillator-based or direct electron detectors. This work advances the reliability of EMCD as a quantitative tool for
magnetic characterization at the nanoscale with unknown
magnetic structures. The proposed procedures lay the groundwork for improved error handling and SNR optimization in future EMCD studies.
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All authors Hitoshi Makino, Bernd Rellinghaus, Sebastian Schneider, Axel Lubk, Darius Pohl
Materials Science
Anomalous enhancement of magnetism by nonmagnetic doping in the honeycomb-lattice antiferromagnet ErOCl
Yanzhen Cai, Mingtai Xie, Jing Kang et al. (+8 more)
Tuning
magnetic anisotropy through chemical doping is a powerful strategy for designing functional materials with enhanced
magnetic properties. Here, we report an enhanced Er^3+
magnetic moment resulting from nonmagnetic Lu^3+ substitution in the honeycomb-
lattice antiferromagnet ErOCl. Unlike the Curie-Weiss type divergence typically observed in diluted
magnetic systems, our findings reveal a distinct enhancement of magnetization per Er^3+ ion under high
magnetic fields, suggesting an unconventional mechanism. Structural analysis reveals that Lu^3+ doping leads to a pronounced contraction of the c axis, which is attributed to chemical pressure effects, while preserving the layered SmSI-type
crystal structure with space group R-3m. High-resolution Raman spectroscopy reveals a systematic blueshift of the first and seventh crystalline electric field (CEF) excitations, indicating an increase in the axial CEF parameter B_2^0. This modification enhances the
magnetic anisotropy along the c axis, leading to a significant increase in magnetization at low temperatures and under high
magnetic fields, contrary to conventional expectations for
magnetic dilution. Our work not only clarifies the intimate connection between magnetism and CEF in rare-earth compounds, but more importantly, it reveals a physical pathway to effectively tune
magnetic anisotropy via anisotropic
lattice distortion induced by chemical pressure.
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All authors Yanzhen Cai, Mingtai Xie, Jing Kang, Weizhen Zhuo, Wei Ren, Xijing Dai, Anmin Zhang, Jianting Ji, Feng Jin, Zheng Zhang, Qingming Zhang
Materials Science
Molecular Dynamics Study of Irradiation-Induced Defect and Dislocation Evolution in Strained Nickel
Maciej Wilczynski, Mark Fedorov, Tymofii Khvan et al. (+2 more)
Molecular dynamics (MD) simulations were performed to investigate the influence of mechanical strain on irradiation-induced defect and dislocation
evolution in nickel single
crystals subjected to cumulative overlapping 5 keV collision cascades at 300 K. The simulations reveal that tensile strain modifies the dynamics of defect generation and recovery, promoting stress-assisted defect mobility and enhancing defect survival compared to the unstrained case. The heat spike duration and intensity decrease systematically with increasing strain, indicating faster energy dissipation and altered defect recombination behavior under applied stress. Analysis of the dislocation structure shows that Shockley-type partial dislocations dominate the microstructural response, while Hirth and other dislocation types remain comparatively minor. Both the total and Shockley dislocation densities reach a saturation value of $~10^{16}m^{-2}$ , marking the establishment of a steady-state microstructure governed by the balance between dislocation accumulation and recovery. The
evolution of the total dislocation density with strain is successfully described by the Kocks-Mecking model, demonstrating its applicability to strain-dependent irradiation effects in metallic systems
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All authors Maciej Wilczynski, Mark Fedorov, Tymofii Khvan, F. Javier Dominguez-Gutierrez, and Jacek Jagielski
Materials Science
Energy evolution in nanocrystalline iron driven by collision cascades
Ivan Tolkachev, Daniel R. Mason, Max Boleininger et al. (+2 more)
Nanocrystalline materials are promising candidates for future fusion reactor applications, due to their high density of grain boundaries which may serve as sinks for irradiation induced defects. We use molecular dynamics to simulate collision cascades in nanocrystalline iron and compare these to collision cascades in initially defect free single
crystals. We create nanocrystalline samples via Voronoi tessellation of initially randomly placed grain seeds and via severe plastic shearing. An irradiation induced annealing is observed whereby after ~ 2 displacements per atom (dpa), irradiation drives all simulation
cells to a single crystalline state. Irradiation-induced defects that distort the
lattice generate elastic strain, so we use excess potential energy as a measure of defect content. At low doses, the Voronoi samples feature a few large, low energy grains, whereas the sheared samples show many small, high energy grains due to the high defect and grain boundary content caused by severe deformation. As dose increases beyond 1 dpa however, all nanocrystalline samples converge to a similar behaviour. Excess potential energy mirrors this trend, plateauing above ~ 4 dpa. We hypothesise that the initially pristine
cells will also reach a similar plateau after 5 dpa, which is seemingly confirmed by running a single instance of each
cell type to 10 dpa. A model is developed to explain the energy
evolution.
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All authors Ivan Tolkachev, Daniel R. Mason, Max Boleininger, Pui-Wai Ma, Felix Hofmann
Materials Science
Observation of hexagonal close-packed water ice at conditions in ice giant planetary interiors
Alexis Forestier, Gunnar Weck, Sandra Ninet et al. (+4 more)
Using synchrotron x-ray diffraction in
laser-heated diamond anvil
cells, we report the observation of an hexagonal close-packed (hcp) phase of water ice at high pressure and temperature conditions. Above 200 GPa and 1800 K, the hcp phase becomes dominant upon entering the superionic regime, as evidenced by anomalous thermal expansion. Observations are consistent with the hcp phase becoming thermodynamically more stable than the face-centered cubic (fcc) phase via a martensitic transition extending across the 130 - 200 GPa pressure range, within the superionic regime. Hcp ice is also observed to emerge from stacking disorder developing within the fcc oxygen
lattice upon cooling, during its reversion to the bcc phase. The presence of an fcc-hcp martensitic transition in the superionic regime of warm dense ice may have implications for planetary models of Uranus and Neptune.
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All authors Alexis Forestier, Gunnar Weck, Sandra Ninet, Gaston Garbarino, Mohamed Mezouar, Frédéric Datchi, Paul Loubeyre
Materials Science · Cross-listed from cond-mat.str-el
Soft and hard x-ray orbital-resolved photoemission study of a strongly correlated Cd-Ce quasicrystal approximant
Goro Nozue, Hidenori Fujiwara, Satoru Hamamoto et al. (+15 more)
We have investigated the orbital-dependent electronic states of Cd6Ce, a prototype of strongly correlated rare-earth-based Tsai-type quasicrystals and approximants (ACs) by soft and hard x-ray photoemission spectroscopy. Our results reveal that the 4f orbitals are predominantly hybridized with the valence-band electrons far from the
Fermi level (EF), in sharp contrast to the hybridization with conduction electrons at EF seen for the intermetallic Ce-based compounds. This anomalous hybridization should be taken into account in discussing the unresolved
magnetic ground state in Cd6Ce. These findings suggest that Cd-based ACs, some of which show the multi-step
magnetic transitions, could provide a new platform for investigating novel
magnetic properties that cannot be understood within the conventional framework of hybridization at EF.
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All authors Goro Nozue, Hidenori Fujiwara, Satoru Hamamoto, Miwa Tsutsumi, Akane Ose, Takayuki Kiss, Atsushi Higashiya, Atsushi Yamasaki, Yuina Kanai-Nakata, Shin Imada, Masaki Oura, Kenji Tamasaku, Makina Yabashi, Tetsuya Ishikawa, Farid Labib, Shintaro Suzuki, Ryuji Tamura, Akira Sekiyama
Materials Science · Cross-listed from cond-mat.mes-hall
Identifying geometric third-order nonlinear transport in disordered materials
Zhen-Hao Gong, Zhi-Hao Wei, Hai-Zhou Lu et al. (+1 more)
In nonlinear transport, the
quantum-
geometric effects can generate higher-harmonic voltages in response to a driving current, which has defined a fast-moving field of intense interest. However, in realistic materials where disorder scattering also contributes to nonlinear transport, identifying the
geometric mechanisms remains a challenge. In particular, a theoretical framework for data analysis is still lacking for nonlinear transport at any order. Here, we develop a mechanism-resolved and
symmetry-guided framework for identifying mechanisms of third-order nonlinear transport in disordered materials. We find a total of 20 mechanisms of third-order nonlinear transport, by treating
quantum-
geometric and disorder-mediated mechanisms on an equal footing. More importantly, we propose a protocol of data analysis that combines
symmetry diagnosis of
magnetic point groups and scaling law of relation between the third-order nonlinear
Hall conductivity and linear longitudinal conductivity. We identify characteristic fingerprints in the scaling-law weights, which allow the mechanisms to be quantitatively distinguished in experiments. We have applied the protocol to identify the
geometric mechanisms in materials with and without time-reversal
symmetry, including 2D materials, topological materials, and altermagnets. The theory can be generalized to arbitrary orders of nonlinear transport, further promoting nonlinear transport as a probe of
geometric effects and phase transitions in
quantum materials.
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All authors Zhen-Hao Gong, Zhi-Hao Wei, Hai-Zhou Lu, X. C. Xie
Materials Science
Unlocking Dynamic Luminescent Mapping of pH with Sustainable Lignin-Derived Carbon Dots with Multimodal Readout Capacity
Maja Szymczak, Jan Hočevar, Jernej Iskra et al. (+4 more)
In this work, we demonstrate the use of CQDs synthesized from lignin - currently one of the most abundant and underutilized by-products of paper and pulp production - for advanced pH monitoring applications. The presented approach integrates green chemistry principles with an operator-friendly, low-cost, and practical solution for spatial and temporal pH measurement. CQDs functionalized with m-aminophenylboronic acid enable highly sensitive and reversible pH readouts through two complementary mechanisms: ratiometric monitoring of emission band intensities, and direct visual observation of colorimetric changes reflected in the CIE1931 chromaticity coordinates. The system achieves maximal sensitivities of 137 percent per pH unit and 49.5 percent per pH unit, respectively, while simultaneously maintaining high measurement resolution and full reproducibility of the readouts, placing it among the most effective CQD-based pH sensors reported to date. Here, we demonstrate the capability of 2D luminescent imaging of pH distributions, allowing for both spatially resolved and time-resolved monitoring. Employing just an excitation source, a digital camera or smartphone, and RGB channel analysis, the setup eliminates the necessity for specialized filters or sophisticated instrumentation. The combination of
multimodal readout strategies with the capacity for large-area visualization establishes lignin-derived CQDs as a sustainable and practical platform for pH sensing. By simultaneously addressing the challenges of waste valorization and the demand for innovative sensing technologies, this solution fulfills the requirements of both environmentally responsible material design and next-generation pH sensor development.
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All authors Maja Szymczak, Jan Hočevar, Jernej Iskra, Darja Lisjak, Jelena Papan Djaniš, Lukasz Marciniak, Karolina Elzbieciak-Piecka
Materials Science · Cross-listed from math-ph
Peierls Instability in Hexagonal Lattices
David Gontier, Thaddeus Roussigné and Éric Séré
We investigate a conventional tight-binding model for
graphene, where distortion of the honeycomb
lattice is allowed, but penalized by a quadratic energy. We prove that the optimal 3-periodic
lattice configuration has Kekulé O-type
symmetry, and that for a sufficiently small elasticity parameter, the minimizer is not translation-invariant. Conversely, we prove that for a large elasticity parameter the translation-invariant configuration is the unique minimizer.
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