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Physics Condensed Matter Materials Science

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Friday 1 May

Materials Science

Determination of Density Functional Tight Binding Models for Cerium-containing Materials

Nir Goldman, Artem Samtsevych and Chiara Panosetti

We have developed Density Functional Tight Binding models for cerium and cerium oxide with generalized gradient approximation and hybrid functionals that accurately predict the electronic band structure of different cerium polymorphs as well as the insulating oxide. We show that determination of a many-body repulsion energy with the Chebyshev Interaction Model for Simulation correctly predicts cerium allotropic energetic ordering with a minimal training created from small-scale molecular dynamics calculations of a single phase, only. Our approach determines DFTB models for both electronic and material property predictions that retain a high degree of transferability.
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Materials Science

Oxygen Vacancies at Dislocation Core Modulate Plasticity in Strontium Titanate

Min-Chul Kang, Chunxu Yan, Alexander Frisch et al. (+3 more)

Dislocation core chemistry in oxides critically influences mechanical behavior and functionality; yet the evolution of core chemistry during the dislocation motion in them has not been directly observed. Here, using SrTiO3 as a model material, we combine aberration-corrected scanning transmission electron microscopy and electron energy-loss spectroscopy with atomic-level molecular dynamics (MD) simulations to correlate the <110>{1-10} dislocation core structure, oxygen vacancy density, charge state, and mobility with each other. We find that the mechanically induced dislocation loops exhibit dissociated cores, whose oxygen vacancy density depends on the gliding distance: short loops are Ti-reduced and oxygen-deficient at the edge dislocation core, whereas longer loops remain close to stoichiometry in both the edge and screw components. MD simulations reveal that kink-assisted edge dislocation glide in SrTiO3 leaves oxygen-deficient trails behind, modulating the oxygen content inside the edge core. These results demonstrate that oxygen-vacancy evolution at the dislocation core intrinsically couples with plasticity in ionic crystals, suggesting a mechanism for oxygen vacancy-dependent dislocation mobility in plastically deformed oxides.
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All authors Min-Chul Kang, Chunxu Yan, Alexander Frisch, Xufei Fang, Liming Xiong, Lin Zhou

Materials Science

TrueEBSD in MTEX: automatic image matching for correlative microscopy applications

Vivian Tong, Stefan Olovsjö, Rachid M'Saoubi et al. (+3 more)

TrueEBSD is an open-source MATLAB program for image alignment and spatial distortion correction of images and electron backscatter diffraction (EBSD) maps. We have re-implemented TrueEBSD as an add-on to MTEX, an established toolbox for EBSD data analysis. Spatial alignment enables correlative analysis methods, such as augmenting EBSD orientation maps with data from other imaging modes. The augmented EBSD maps can then be analysed further using MTEX. We demonstrate TrueEBSD on two example case studies: one for measuring Co phase fraction and WC contiguity in a WC-Co composite, and another for determining the relative susceptibility of grain boundaries to void formation in a copper polycrystal. In both examples, the EBSD map was augmented with scanning electron microscopy (SEM) image data. This enabled quantitative crystallographic measurements which would not be possible from analysing the EBSD maps and images separately.
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All authors Vivian Tong, Stefan Olovsjö, Rachid M'Saoubi, Mathias Grabner, Manuel Petersmann, Liam Wright

Materials Science

Born-Qualified: An Autonomous Framework for Deploying Advanced Energy and Electronic Materials

Steven R. Spurgeon, Milad Abolhasani, Frederick Baddour et al. (+28 more)

Autonomous science is transforming how we discover materials and chemical systems for advanced energy technologies. However, many initially promising systems never reach deployment. This "valley of death" stems from optimization that prioritizes laboratory metrics over industrial viability. We propose a new strategy: "born-qualified" autonomous development, which embeds manufacturability, cost, and durability constraints from the outset. This approach is enabled by four pillars, including the development of multi-objective metrics, causal models, a modular infrastructure, and embedding manufacturing in the discovery loop. Realizing this vision will require sustained, community-wide commitment, but the potential return on that investment is commensurate with the scale of the challenge.
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All authors Steven R. Spurgeon, Milad Abolhasani, Frederick Baddour, Ryan B. Comes, Vinayak P. Dravid, Hilary Egan, Patrick Emami, Robert W. Epps, Davi M. Fébba, Renae Gannon, E. Ashley Gaulding, Ayana Ghosh, Kenny Gruchalla, Grace Guinan, Taro Hitosugi, Michael Holden, Sergei V. Kalinin, Yangang Liang, John S. Mangum, Matthew J. Olszta, Nathaniel H. Park, Axel Palmstrom, Michelle A. Smeaton, Brooks Tellekamp, Nicholas E. Thornburg, Raymond R. Unocic, Daniela Ushizima, Rama K. Vasudevan, Robert White, Andrew Young, Andriy Zakutayev

Materials Science

Coordination Engineering of Dual-Atom Catalysts for Overall Water Splitting: Mechanistic Insights from Constant-Potential First-Principles and Machine Learning

Jiahang Li, Suhang Li, Chong Yan et al. (+4 more)

The rational design of bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for achieving efficient and cost-effective overall water splitting. Atomically dispersed transition-metal catalysts, including single-atom catalysts and dual-atom catalysts (DACs), have emerged as a prominent class of heterogeneous catalysts, in which coordination engineering plays a decisive role in tuning catalytic performance. Herein, we explore coordination-engineered bifunctional overall water splitting electrocatalysts using graphene-supported DACs (TM1TM2-C6-xNx) as model systems. By tuning C/N coordination and dual-metal combinations (Fe, Co, Ni, and Cu), a library of 228 structures was constructed. A three-step screening strategy, combining constant-charge and constant-potential density functional theory with kinetic analysis of proton-coupled electron transfer (PCET), identifies 24 highly active candidates (TM1TM2 = CoNi, CoCu and Co2) with mixed C/N coordination for OER. These catalysts exhibit overpotentials comparable to that of IrO2 and low PCET barriers (lower than 0.40 eV), among which 22 also show high HER activity. Machine learning reveals clear coordination-dependent structure-performance relationships. Such bifunctionality arises from coordination engineering that enables the simultaneous optimization of OER intermediate adsorption and the hydrogen binding strength for HER. This work establishes coordination engineering as an effective strategy for designing high-performance bifunctional dual-atom electrocatalysts for overall water splitting.
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All authors Jiahang Li, Suhang Li, Chong Yan, Jiajun Yu, Qinzhuang Liu, Ruo-Ya Wang, Dongwei Ma

Materials Science

Coordination-Induced Tuning of Ligand-Centered Red Emission in a cis-[Cd(Tz)2(py)2] Complex for Light-Emitting Diodes

Samara M. da Silva, R. F. Silva, A. Nonato et al. (+6 more)

Organic–inorganic complexes are promising materials for light-emitting applications. Here, we report a new organometallic complex, cis-[Cd(Tz)$_2$(py)$_2$], featuring a distorted octahedral Cd(II) coordination environment. IR and Raman spectroscopy reveal pronounced coordination-induced changes, particularly in the Raman response of the triazene moiety, indicating electronic and structural perturbation upon Cd(II) complexation. Hirshfeld surface analysis shows that the crystal packing is mainly governed by H$\cdots$H, O$\cdots$H/H$\cdots$O, and C$\cdots$H/H$\cdots$C contacts, whereas $\pi$–$\pi$ stacking interactions contribute modestly. Solid-state UV–Vis spectroscopy reveals broad absorption from $\sim$700 to 200 nm and a direct optical band gap of 1.83 eV, indicating semiconductor-like behavior. Photoluminescence measurements show a broad emission band at 500–850 nm with enhanced red contribution upon coordination. The emission is mainly assigned to ligand-centered transitions ($\pi \rightarrow \pi^*$ and $n \rightarrow \pi^*$), consistent with the $d^{10}$ configuration of Cd(II), which suppresses metal-centered and charge-transfer processes. The CIE chromaticity coordinates confirm warm emission, highlighting the potential of cis-[Cd(Tz)$_2$(py)$_2$] for red-emitting optoelectronic applications.
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All authors Samara M. da Silva, R. F. Silva, A. Nonato, Paulo Villis, Rodrigo S. Corrêa, L. C. Gómez-Aguirre, C.W.A. Paschoal, Pedro I. S. Maia, Benedicto A. V. Lima

Materials Science · Cross-listed from physics.app-ph

High-pressure magnetic transition in iron observed via diamond quantum sensing

Kouki Yamamoto, Kenshin Uriu, Ryotaro Suda et al. (+5 more)

Diamond quantum sensors offer high precision and spatial resolution as magnetic probes, making them promising for a wide range of applications. While diamond anvil cells (DACs) can generate extremely high pressures, techniques for magnetometry under such conditions remain limited. By fabricating an ensemble of NV centers directly on the anvil diamond surface, we enable precise magnetic measurements under high pressure. In this work, we employ this NV ensemble to image the stray magnetic field of iron up to 30 GPa, enabling the observation of the magnetic transition ($\alpha$-$\varepsilon$ transition) in iron.
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All authors Kouki Yamamoto, Kenshin Uriu, Ryotaro Suda, Misaki Sasaki, Mari Einaga, Katsuya Shimizu, Kento Sasaki, Kensuke Kobayashi

Materials Science · Cross-listed from cond-mat.str-el

Dynamical magnetotropic susceptibility as a new probe of Kitaev materials and beyond

João C. Inácio, J. Schwab, G. Rakhmanova et al. (+8 more)

The magnetotropic susceptibility, $k(\omega)$, probes ultra-low-frequency uniform ($\boldsymbol{q}=0$) spin and charge fluctuations in a crystal mounted on an oscillating cantilever: its real part shifts the oscillation frequency, while its imaginary part characterises the induced damping. We derive $k(\omega)$ within linear response theory for a generic correlated-electron Hamiltonian, showing that its real part is sensitive to magnetic anisotropy and its imaginary part encodes the uniform dynamical spin susceptibility, even for spin-symmetric insulators, while in metals it reveals eddy-current damping conditions. Using auxiliary-field quantum Monte Carlo, we compute $k(\omega)$ for microscopic models of $\alpha$-RuCl$_3$, finding that the low-temperature $k(\omega=0)/T$ scaling with $B/T$ is a signature of dominant Kitaev coupling, robust to optical phonons, while the dynamical response shows local-moment-like features. We highlight applications to Kondo destruction quantum criticality, relevant to strange metallicity and unconventional superconductivity.
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All authors João C. Inácio, J. Schwab, G. Rakhmanova, S. Safari, V. Zambra, H. Nasir, S. Khim, S. Paschen, K. A. Modic, Fakher F. Assaad, Toshihiro Sato

Materials Science

An Unsupervised Machine Learning-based Framework for Wafer Scale Variability Analysis and Performance Prediction of Ferroelectric Hf0.5Zr0.5O2 Thin Film Capacitors

Anika Anu and Sayani Majumdar

Fabrication process-induced performance variability remains a formidable barrier in the high-volume manufacturing of semiconductor chips. With skyrocketing Artificial Intelligence (AI) workload, demand for non-volatile and computational memories is growing exponentially. As embedded non-volatile memory, ferroelectric Hf0.5Zr0.5O2 emerged as a strong candidate due to their CMOS back-end-of-line (BEOL) compatibility, scalability and high performance. However, their sensitive crystallization kinetics leads to significant device-to-device (D2D) non-uniformity leading to unpredictability of performance over wafer scale. In this work, we demonstrate unsupervised machine learning can analyze intra-die D2D variations and predict performance of "unseen" dies efficiently. We present a framework utilizing Principal Component Analysis (PCA) and K-Means clustering to analyze D2D performance variations in HZO capacitors and building on data from multiple dies, we move beyond traditional descriptive statistics to a predictive "Virtual Metrology" approach that separates performance categories, defined by key parameters like remanent polarization (Pr) and coercive voltage (Vc). The analysis further extends to comparing uniformity across different dies across the wafer showing the proposed methodology can accurately predict device performance on untested dies with a low Mean Absolute Percentage Error (MAPE) in the range of 5-10%, suggesting a robust path for accelerated yield improvement and reduced metrology overhead.
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Materials Science

Magnetic Behavior of Ferro-, Antiferro-, and Ferrimagnetic Systems in the Griffiths Phase: A Theoretical Study

Sumanta Mukherjee

In this report, we provide a theoretical framework for the magnetic behavior of the Griffiths phase, which, along with three-dimensional spin-1/2 Ising ferromagnetic systems, can be extended to antiferromagnetic as well as ferrimagnetic systems. We find that the magnetic behavior in the Griffiths phase of three-dimensional antiferromagnetic and ferrimagnetic systems is more unusual than that of conventional ferromagnetic systems. However, this study offers a possible framework for the identification of Griffiths phase behavior in three-dimensional antiferromagnetic and ferrimagnetic systems.
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Materials Science

An Advanced Epitaxial Strategy Enabling Vertical GaN Devices on Silicon Wafers

Fumio Kawamura, Takeyoshi Onuma and Kazutaka Mitsuishi

While vertical GaN-on-silicon architectures promise a transformative leap in cost-effective power electronics and high-resolution micro-LEDs, their deployment remains bottlenecked by the high electrical resistance of conventional epitaxial buffer layers. Here, a universal and straightforward sputtering-based strategy is presented to realize high quality GaN epitaxial films on Si(111) substrates characterized by exceptionally low vertical resistance, ohmic behavior, and robust thermal stability. This technique centers on the in-situ formation of a sub nanometer (0.5 nm) silicide-based template via rapid thermal annealing method demonstrating unprecedented versatility across 25 different metallic species. Scanning transmission electron microscopy (STEM) reveals that a unique amorphous like interlayer (AL-IL) effectively accommodates lattice mismatch and relaxes epitaxial strain. These AL-IL templates further serve as high performance platforms for metalorganic chemical vapor deposition (MOCVD) overgrowth, successfully bridging the gap between scalable, low-cost fabrication and device-grade vertical performance.
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Materials Science

Kinetically Arrested Twin-Domain State in Formamidinium Lead Iodide

Xia Liang, Milos Dubajic, Zezhu Zeng et al. (+4 more)

Hybrid lead halide perovskites exhibit a delicate interplay between average crystallographic symmetry, local structural disorder and A-site orientational dynamics, giving rise to unusual vibrational and electronic behaviour. Here, we combine large-scale molecular dynamics with a density-functional-theory-accurate machine learning force field to resolve the structural dynamics of perovskites across mesoscopic length scales. In formamidinium lead iodide FAPbI$_{3}$, we identify a high-temperature $\alpha$ phase with dynamic local order and correlated tilt nanodomains, an ordered $\gamma$ phase with long-range $a^{+}a^{+}a^{+}$ tilt coherence, and, below $\sim$100 K, a history-dependent $\gamma'$ state consisting of locally $\gamma$-like nanoscale regions separated by sharp twin-like boundaries. This low-temperature disordered state is not a distinct bulk polymorph, but a kinetically arrested metastable twin-domain network selected by the interplay between shallow tilt energetics and slowing FA reorientation. This picture provides a consistent explanation for the low-temperature diffuse scattering features observed experimentally, and accounts for the broadened low-energy vibrational response found in the simulations. Furthermore, this unique structural landscape imprints a spatially varying electronic disorder that directly impacts macroscopic optoelectronic properties, evidenced by an anomalous increase in the Urbach energy at low temperatures. Our results reconcile the debated low-temperature behaviour of FAPbI$_{3}$ in terms of competition between ordered and arrested structural states, and show more broadly that in hybrid perovskites the organic cation can actively select the macroscopic structural and electronic response through its reorientation kinetics, placing thermal history on equal footing with composition as a determinant of structural and optoelectronic properties.
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All authors Xia Liang, Milos Dubajic, Zezhu Zeng, Yang Lu, Johan Klarbring, Samuel D. Stranks, Aron Walsh

Materials Science · Cross-listed from cond-mat.mes-hall

Investigation of nonlocal transport associated with the orbital Hall effect in Ti

Keitaro Takashina, Naoki Yano, Asahi Oe et al. (+3 more)

We investigate nonlocal transport in single-layer Ti Hall bars to explore signatures of orbital-current transport driven by the orbital Hall effect. Despite the negligible spin Hall effect in Ti, we observe a finite nonlocal resistance in the single-layer Ti Hall bar and study its dependence on the central channel width. Finite-element simulations show that the measured signal contains a sizable Ohmic bypass contribution. However, the bypass contribution is strongly suppressed at small channel widths and cannot fully account for the observed nonlocal resistance even when variations in the Ti resistivity are taken into account. Our results therefore suggest an additional nonlocal contribution distinct from the Ohmic bypass background, which may be associated with orbital transport driven by the orbital Hall effect in Ti.
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All authors Keitaro Takashina, Naoki Yano, Asahi Oe, Mari Taniguchi, Shuto Kimura, Kazuya Ando

Materials Science · Cross-listed from cond-mat.mes-hall

Polarization-controlled effective Rabi dynamics in driven Graphene: A Floquet-Magnus approach

V. G. Ibarra-Sierra, J. L. Cardoso, C. Flores-Valente et al. (+2 more)

Polarization ellipticity $\beta$ and the relative angle $\Delta$ between electron momentum and driving field act as independent control parameters for coherent dynamics in periodically driven Dirac systems. In this work, we analyze the dynamics of resonantly driven Dirac electrons in graphene under elliptically polarized electromagnetic radiation using the Floquet-Magnus expansion. Working in the interaction picture and applying a rotating-wave-type transformation, we derive an effective two-level Hamiltonian that governs the macromotion at resonance ($\omega = \Omega/2$). The resulting quasienergy splitting depends nontrivially on $\beta$ and $\Delta$ through interference between the Bessel harmonics $J_0(\zeta)$ and $J_2(\zeta)$. Circular polarization ($\beta = \pm 1$) restores rotational symmetry and yields a $\Delta$-independent effective Rabi frequency, whereas elliptical and linear polarizations produce anisotropic responses with a $\pi$-periodic angular modulation. Beyond spectral properties, we identify a polarization-induced phase that acts as an effective initial Floquet kick, shifting the effective initial conditions and producing measurable shifts in the timing of occupation oscillations, whose sign depends on both helicity and relative orientation. Through an explicit Fourier decomposition of the time-evolution operator, we separate macromotion from micromotion contributions and validate the zeroth-order Magnus approximation via numerical simulations, achieving root-mean-square errors of $\sim 1\%$ over 100 driving periods in the weak-field regime. These results establish polarization ellipticity and relative orientation as tunable and experimentally accessible knobs for quantum control in two-dimensional Dirac materials, with direct implications for time-resolved spectroscopy.
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All authors V. G. Ibarra-Sierra, J. L. Cardoso, C. Flores-Valente, A. Kunold, J. C. Sandoval-Santana

Materials Science

Beyond Structure: Revolutionising Materials Discovery via AI-Driven Synthesis Protocol-Property Relationships

Guillaume Lambard

The current structure-centric paradigm in artificial intelligence (AI)-driven materials discovery, despite delivering thousands of candidate structures, is stalling at a critical barrier: the synthesizability gap. We argue that closing this gap demands a pivot to a synthesis-first paradigm in which executable synthesis protocols, not just atomic configurations, are treated as primary design variables. We outline a roadmap built on three pillars: (i) representing synthesis procedures as machine-readable protocols, (ii) deploying generative and inverse-design models to propose actionable reaction pathways and recipes, and (iii) integrating closed-loop optimisation to refine protocols against experimental realities and sustainability constraints. Framed in terms of the causal backbone P->X->y from protocol P to structure X and properties y, this perspective sets out methodological building blocks, standards needs and self-driving laboratory (SDL) integration strategies to accelerate reproducible, data-first materials discovery.
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Materials Science

Tailoring Mechanical Properties of Germanium Anodes via Metal Incorporation for Improved Cycle Stability

Koki Nozawa, Noriyuki Saitoh, Noriko Yoshizawa et al. (+2 more)

Achieving long-term stability in high-capacity lithium-ion battery anodes remains a critical challenge. In this study, we present a materials-intrinsic strategy for extending the cycle life of Ge, a promising next-generation anode material, through trace doping with metal elements. We systematically investigated the effects of small additions of various metals and found that elements with large atomic size, particularly Yb, markedly improved the cycling stability without sacrificing the initial capacity, while appropriate Yb doping enhanced the anode lifetime by approximately a factor of three. Structural and electrochemical analyses revealed that this improvement originates from mechanical softening of the Ge anode, which suppresses lithiation-induced damage such as cracking and delamination. Nanoindentation measurements further showed a strong negative correlation between dopant atomic size and film hardness, establishing anode softening as a new design principle for damage-tolerant electrodes. Although Yb doping reduced the rate capability at high C-rates, the present results demonstrate a clear shift in design strategy from volume-change suppression to mechanical compliance. These findings provide a useful framework for stabilizing high-capacity alloy anodes through atomic-scale mechanical control.
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All authors Koki Nozawa, Noriyuki Saitoh, Noriko Yoshizawa, Takashi Suemasu, Kaoru Toko

Thursday 30 April

Materials Science

Homogenization of one-dimensional periodic rod networks as special Cosserat rods

Vinayak and Ajeet Kumar

One-dimensional periodic rod networks are the structures that are obtained by periodically assembling its microstructural unit, a network of rods itself, in just one direction. In this work, we present a scheme for obtaining the nonlinear constitutive response of such structures when homogenized macroscopically as a continuum rod. To accurately capture arbitrary and large deformations, the geometrically exact special Cosserat rod theory is used for modeling the rod at both micro- and macroscales. By assuming the periodic structure to be strained uniformly, at macroscale, along its arc length, the full structure problem is reduced to just that of its microstructural unit but subjected to helically periodic boundary condition. The microscale problem, consisting of a network of rods and formulated in a variational setting, is solved in the presence of rod-joint constraints and helically periodic boundary conditions. The expressions for the macroscale rod's stress resultants, i.e. internal contact force and moment, and stiffnesses are then obtained. Finally, several numerical examples having different microstructural units are presented to demonstrate our method. First, the results corresponding to simpler square and cross microstructural units are presented and validated with the existing literature. Square microstructural units having helical constituent rods are then taken up which have application as artificial muscle fiber material. Eventually, homogenization of auxetic tubular metamaterials is performed. It is shown how various design parameters of these microstructural units can be tuned to obtain the desired macroscopic response.
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Materials Science · Cross-listed from physics.bio-ph

Statistical analysis of virion-cell interactions mediated by peptide nanofibrils and peptide amphiphiles using STEM tomography

Philipp Rieder, Julia La Roche, Orkun Furat et al. (+8 more)

Peptide nanofibrils (PNFs) and peptide amphiphiles (PAs) are promising tools for enhancing viral transduction and gene transfer. However, quantitative insight into how their supramolecular architecture governs virion-cell interactions is limited. Here, we introduce a framework for the acquisition, processing, and statistical analysis of scanning transmission electron microscopy (STEM) tomograms to objectively quantify peptide-virion-cell interactions. Using four transduction-enhancing peptides (D4, Vectofusin-1, palmitic acid-PA (pal-PA), and eicosapentaenoic-PA (eic-PA)), peptide aggregate morphology, interfacial contact areas, and the spatial organization of virions with respect to peptides and cells were analyzed using advanced geometric descriptors. All peptides efficiently captured virions, resulting in few free virions, but they differ in how strictly virions were spatially confined near the cell surface. These differences reflect alternative spatial organization strategies, which are likely crucial factors influencing transduction-enhancing efficacy. Our approach provides a novel, generalizable method to evaluate infection-enhancing nanomaterials and guides the rational design of next-generation peptide assemblies for therapeutic viral delivery.
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All authors Philipp Rieder, Julia La Roche, Orkun Furat, Annalena Kuhn, Lena Rauch-Wirth, Kübra Kaygisiz, Fabian Zech, Jan Münch, Clarissa Read, Rüdiger Groß, Volker Schmidt

Materials Science · Cross-listed from physics.app-ph

Programmable Integrated Magnonic Meshes

Piero Florio, Matteo Vitali, Valerio Levati et al. (+9 more)

Integrated circuits are a cornerstone of modern information technology, and analog wave-based architectures could enable fast and efficient processing beyond conventional charge electronics. In magnonics, spin waves provide a highly tunable, compact and energy-efficient medium for on-chip microwave signal transport and processing. However, progress has been limited to isolated elements or short devices, severely limiting the overall functional complexity and scalability. Here we realize the key elements of universal magnonic circuitry, using a single-step direct laser writing process in yttrium iron garnet, and monolithically cascade them in multi-stage programmable devices and networks. Using magneto-optical Kerr effect microscopy, we show efficient spin-wave propagation and preserved phase coherence in waveguide structures for hundreds of wavelengths. In coupled waveguides, we observe complete and periodic power transfer over several coupling lengths, and in phase shifters we achieve arbitrary, tunable phase delays. By cascading these elements, we realize programmable splitters, frequency demultiplexers, and phase-controlled 2x2 routers, where output power and relative phase can be programmed on demand via external fields. Finally, we realize programmable magnonic interferometric meshes for on-chip radio-frequency signal routing, with up to six magnonic inputs and outputs and seven cascaded stages, without the need for intermediate amplification. These direct-write cascaded networks bridge a long-standing gap in magnonic scalability, offering a viable pathway toward integrated, large-scale architectures for both classical and quantum processing.
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All authors Piero Florio, Matteo Vitali, Valerio Levati, Rasheed M. Ishola, Luca Ciaccarini Mavilla, Nora Lecis, Carsten Dubs, Riccardo Bertacco, Marco Madami, Silvia Tacchi, Daniela Petti, Edoardo Albisetti

Materials Science

Dilute Zn alloying in biodegradable Mg wires: microstructure, mechanical performance, and degradation behavior

Jiří Ryjáček, Leonard Hlodák, Jiří Liška et al. (+3 more)

Dilute Mg-Zn wires are of great interest for biodegradable small-bone fixation, as magnesium degradation can support bone-related processes, while low zinc additions may provide biological benefits without compromising biocompatibility. In this work, the influence of Zn content below the room-temperature solubility limit was assessed in Mg-Zn wires intended for resorbable implant applications. Mg-0.4Zn, Mg-0.6Zn, Mg-0.8Zn, and Mg-1.5Zn alloys were processed by single-step direct hot extrusion into thin wires and characterized by correlative microstructural analysis, tensile testing, bending experiments, and in vitro degradation. All compositions achieved a recrystallized fine equiaxed grain size of 5.0-5.9 um and exhibited ultimate tensile strengths of 246-256 MPa with elongations of 23-28 %. In these thin wires, Zn content had only a limited effect on grain size, tensile properties, and bending behavior, although lower-Zn alloys showed a pronounced sharp yield point. Bending was governed mainly by extrusion texture and preserved reversible plasticity through twinning and detwinning. Simulated body fluid caused rapid localized degradation and loss of mechanical integrity within 7 days, while the biologically more relevant DMEM-based medium better reflected the expected in vivo response. Together, these findings support dilute Mg-Zn wires as a simple material platform for the development of future resorbable bone fixation devices.
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All authors Jiří Ryjáček, Leonard Hlodák, Jiří Liška, Jan Pinc, Tomáš Herma, Karel Tesař

Materials Science · Cross-listed from physics.data-an

FitED: A User-Centric, Extensible Software Environment for Robust Peak-Profile and General Functional Data Fitting

Mustafa Mahmoud Aboulsaad

Reliable parameter extraction from experimental data is essential for quantitative analysis across spectroscopy, diffraction, photoluminescence, chromatography, microscopy, and time-resolved measurements. However, nonlinear fitting often remains difficult to reproduce, especially when complex models, correlated parameters, uncertain derived quantities, and user-dependent fitting choices are involved. We present FitED, a Python-based desktop application for nonlinear fitting of one-dimensional scientific data that combines an accessible graphical interface with a transparent and flexible numerical backend. FitED supports conventional peak profiles, including Gaussian, Lorentzian, Pseudo-Voigt, and exact area-normalized Voigt functions, as well as arbitrary user-defined analytical models for broader experimental applications. The software integrates local and global-search-assisted optimization strategies, automated model initialization, repeated stability testing, parameter-correlation analysis, and covariance-based propagation of uncertainty for derived quantities. By combining interactive usability with uncertainty-aware analysis and structured export of fitting results, FitED provides a practical platform for reproducible and interpretable fitting of experimental data. The software is intended to support both routine analysis and advanced model evaluation while preserving the parameter-level control required by experimental researchers.
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Materials Science

Uniaxial strain-driven ferroelastic domain control in LaAlO3

Matthias Roeper, Robin Buschbeck, Jakob Wetzel et al. (+15 more)

Multiferroic domain walls in functional oxides exhibit properties distinct from the bulk and are increasingly exploited as active elements in nanoelectronic and photonic devices. Deterministic control of domain populations has typically remained limited to local control, or removal with temperature. Here we demonstrate continuous, reversible manipulation of the ferroelastic domain structure in single-crystal LaAlO$_3$ using in-situ uniaxial strain. Combining atomic force microscopy, X-ray diffraction, and Raman spectroscopy with first-principles calculations we map the complete microscopic evolution of the twin domain population through the strain-driven transition from the rhombohedral $R\bar{3}c$ ground state toward the predicted orthorhombic $Fmmm$ phase. Applied strains below $0.5\%$ produce pronounced surface flattening and large-scale domain reorganisation, establishing uniaxial strain as a technically accessible control parameter for ferroelastic domain engineering. These results open a route to active, real-time programming of domain architectures in LaAlO$_3$-based heterostructures, with implications for strain-tunable superconducting interfaces, nanoscale phonon-polariton optics, and ultrafast lattice control.
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All authors Matthias Roeper, Robin Buschbeck, Jakob Wetzel, Tobias Ritschel, Anna-Lena Hofmann, Vladyslav Kovtunovych, Mike N. Pionteck, Javier Taboada-Gutiérrez, Alexey B. Kuzmenko, Martina Basini, Vivek Unikandanunni, Iuliia Kiseleva, Jochen Geck, Susanne C. Kehr, Maximilian Lederer, Simone Sanna, Lukas M. Eng, Samuel D. Seddon

Materials Science

Strong coupling between quantized magnon modes in a YIG microstucture and microwaves in a superconducting resonator

Seth W. Kurfman, Philipp Geyer, Anoop Kamalasanan et al. (+6 more)

Strong-coupling experiments based on magnons enable the exploration into on-chip demonstrations involving numerous long-lived excitations. Yttrium iron garnet (YIG) has been considered for decades as a gold standard material for magnonics due to its low-loss magnonic properties. While YIG has successfully demonstrated strong-coupling in macroscopic device geometries, the strong coupling of magnons in truly sub-10 micron YIG structures to date has not yet been realized. This obstacle is due to the difficulty producing large enough effective magnonic mode volume necessary primarily due to thickness limitations of YIG deposition and device fabrication techniques. Here, we demonstrate the use of a microplatelet of YIG, manufactured from a single crystal of YIG via focused ion beam (FIB) techniques, placed on a constricted inductive line of an optimized superconducting lumped element LC resonator to achieve strong coupling between numerous magnon modes and the LC resonator photons. These experimental findings are qualitatively backed by micromagnetic simulations and quantitatively supported by analytical calculations to identify the magnon modes corresponding to the experimentally observed anti-crossings in the microwave transmission signal. Further, we show that these anti-crossings remain even at incredibly low device input powers ($\leq 10$ fW). The fabrication techniques and device geometry enable the deterministic use of numerous confined magnon modes in micron-scale YIG structures for various magnetic field strengths and orientations at substantially reduced device powers. The results here establish a foundational path forward to achieving efficient magnon-based strong-coupling experiments in micron-scale YIG magnetic elements for effective on-chip studies.
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All authors Seth W. Kurfman, Philipp Geyer, Anoop Kamalasanan, Karl Heimrich, Kwangyul Hu, Tharnier O. Puel, Frank Heyroth, Michael Flatté, Georg Schmidt

Materials Science

Multi-scale calculation of light-induced structural changes in low-angle twisted bilayer WSe$_2$

Rafael R. Del Grande and David A. Strubbe

Exciton-phonon interactions in transition metal dichalcogenides (TMD) are strong and lead to phenomena such as coherent phonon generation. When stacked and twisted, their properties can be tuned by the twisting angle. In experiments with 1.1$^\circ$ twisted 2L WSe$_2$, a change of 0.1 Å in the interlayer distance was observed when light was shone on this material, and here we explain the microscopic mechanism behind this. Theoretical works to study such systems are limited because the Moiré unit cell is too large. To overcome this, we combined classical force field relaxations with our implementation of ab initio GW/Bethe-Salpeter excited state forces (ESF). From the relaxations we found that the low-angle twisting induced an in-plane strain field, the AB regions are large enough to be simulated as periodic AB stacked 2L WSe2, and the interlayer force constant becomes softer in relation to the perfect AB stacking. From the ab initio ESF we obtained that the in-plane strain increases the out of plane ESFs. Those two effects combined, the weakening of the interlayer force constant and strain dependence of the ESF, make light-induced changes in the interlayer distance of twisted 2L WSe2 stronger than in the perfectly stacked case, in agreement with experimental observations. Therefore, our results show that the exciton-phonon interactions can be tuned in twisted 2L TMDs and can be observed experimentally, which makes those materials excellent platforms to study light-induced changes in materials.
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Materials Science

Unveiling the potential of NdPO4 magnetocaloric phases in cryogenic refrigeration

M. Balli, L. Attou, S-E. Bouzarmine et al. (+4 more)

The RPO4 orthophosphates (R = rare earth element) have recently attracted a wide interest due to the strong coupling between their electronic, orbital and structural ordering parameters resulting in a variety of functional properties. Herein, we demonstrate that NdPO4 phases synthesized via a facile precipitation growth process unveil promise in low-temperature magnetic cooling. The analysis of their structural properties reveals nanorod forms with diameters of 10 to 20 nm and lengths ranging from 200 to 500 nm while the heat treatment transforms their hexagonal rhabdophane-type structure to a monoclinic anhydrous monazite-type symmetry. Magnetization measurements and DFT calculations show strong antiferromagnetic couplings and the absence of any magnetic ordering in the 2-300 K range. On the other hand, the monoclinic phase of NdPO4 exhibits a large magnetocaloric effect of about 19 J/kg K under 5 T near 3 K, outperforming some reference materials containing more expensive rare-earth elements with high magnetic moments.
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All authors M. Balli, L. Attou, S-E. Bouzarmine, S. Oubad, K. El Maalam, P. Fournier, S. Mangin

Materials Science

Polar Topologies in a Ferroelastic Metal Membrane

Rahil Haria, Noah Schnitzer, T. Ben Britton et al. (+10 more)

Polar metals, materials in which electric polarisation and metallicity coexist, are exceptionally rare because itinerant electrons screen long-range dipoles and favour centrosymmetric structures. Engineering polar textures in a conducting magnet holds promise for reconfigurable spin orbit coupling and magnetoelectric functionality. Here we show that releasing epitaxial SrRuO3 films from their substrates drives a hierarchy of ferroelastic domain refinement from micrometre to nanometre length scales, and that this structural reorganisation spontaneously generates two distinct classes of emergent polar texture that are ubiquitous across the freestanding membrane. Using correlative microscopy from mesoscale electron channelling contrast imaging (ECCI) to atomic resolution scanning transmission electron microscopy (STEM), we demonstrate that electric polarisation emerges selectively at translation-inequivalent antiphase boundaries (APBs). At these boundaries multicomponent aac tilt field undergoes Neel-like interpolation that preserves the in-phase tilt component and amplifies roto flexoelectric coupling, while translation-equivalent boundaries remain nonpolar. The Neel like interpolation at hard APBs and Ising like collapse of all tilt components at easy APBs is corroborated with ab initio calculations. While embedded 90 ferroelastic walls provide an additional mechanistically distinct source of electric polarisation resulting in polar nanoclusters (4 nm). These distinct nanotextures at 90 walls from via elastic accommodation of strain mismatch between variants and rotostriction as the tilt field interpolates across the boundaries. These findings show that, in a membrane form, metal oxides provide a robust platform for hosting nanoscale ferroelastic domains that generate polar textures.
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All authors Rahil Haria, Noah Schnitzer, T. Ben Britton, Yaqi Li, Tom J. P. Irons, Sophia Linssen Pitsaros, Ella Banyas, Geri Topore, Annabel Hoyes, Mariana Palos, Sinead M. Griffin, Katherine Inzani, Michele Shelly Conroy

Materials Science

Machine Learning and Molecular Simulations Reveal Mechanisms of ZIFs Polymorph Selection

Emilio Méndez and Rocio Semino

Zn(imidazolate)$_2$ metal-organic frameworks (MOFs) exhibit a remarkable degree of polymorphism. Because of their promising industrial applications, many research groups have investigated phase transitions, phase diagram and relative stability of these polymorphs. There is now wide consensus in the research community that these MOFs are solvothermally formed via non-classical nucleation mechanisms, in which pre-nucleation clusters are first formed, followed by an intermediate amorphous structure that subsequently reorganizes to yield the final crystalline MOF. However, no study up to date has uncovered which part of the synthesis process determines the final polymorph obtained. In this work, path collective variable metadynamics simulations performed with a partially reactive force field give insights into mechanistic and thermodynamic aspects of the self-assembly of these MOFs. Databases of transient and intermediate synthesis structures are built from the simulations. By developing and applying neural network classifiers over these databases, it is found that both pre-nucleation clusters and the amorphous intermediate structures are polymorph-dependent. These results suggest that polymorph selection happens as early as the pre-nucleation cluster stage.
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Materials Science

From Narrow-gap Semiconductor to Metallic Altermagnet: Optical Fingerprints of Co-Doped FeSb2

R. Mathew Roy, M. Povolotskiy, J. Kirschke et al. (+11 more)

The realization of bulk metallic altermagnetism has remained elusive despite the growing number of candidate materials. Here, we present evidence that moderate cobalt substitution ($\sim$15%) drives the correlated narrow-gap semiconductor FeSb$_2$ into a metallic altermagnetic state persisting up to room temperature. The infrared optical conductivity reveals low-energy interband transitions near 0.1 eV that emerge upon doping and grow with Co concentration. Density functional theory calculations show that these transitions originate exclusively from altermagnetic spin ordering, with spin split bands ($\sim$0.2 eV) of non-relativistic origin, together with spin-orbit coupling induced band splitting of the order of $\sim$5 meV near the Fermi level. Co substitution further leads to Fano lineshapes and mode mixing in the infrared-active phonons, reflecting enhanced electron-phonon coupling and local inversion symmetry breaking, while leaving the altermagnetic spin symmetry intact. Our results establish carrier-tuned FeSb$_2$ as a platform for exploring metallic $d$-wave altermagnetism and its coupling to lattice degrees of freedom.
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All authors R. Mathew Roy, M. Povolotskiy, J. Kirschke, C. Prange, Y. Xia, V. Sundaramurthy, P. Puphal, M. Pinteric, M. van de Loo, A. Kreyssig, T. Zhang, A. E. Böhmer, M. Dressel, M. Wenzel

Materials Science

Radio Frequency Field-Induced Enhancement of Detection Sensitivity in Silicon Nanowire Sensors

Ang Liu, Jingsong Shang, Jiangang J. Du et al. (+2 more)

Sensitive biomarker detection in physiological fluids is often limited by Debye screening, which suppresses electrostatic signals at sensor surfaces. Here we report a sensing approach based on flexoelectric resonance in silicon nanowire field-effect transistors. An applied radiofrequency field induces strain gradients in the nanowires, generating flexoelectric polarization that is amplified at resonant frequencies. This effect enhances the sensitivity of conductance measurements to small surface charge variations associated with biomolecular binding. Using C-reactive protein as a model biomarker, we observe an order-of-magnitude improvement in detection sensitivity compared to conventional operation, with a 62% conductance increase versus 30% without radiofrequency modulation. The high-frequency field also perturbs the electrical double layer, reducing Debye screening in high-ionic-strength environments. These combined effects enable direct biomarker detection without sample dilution. This work establishes flexoelectric resonance as a general strategy for improving nanoscale biosensing performance in physiologically relevant conditions.
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All authors Ang Liu, Jingsong Shang, Jiangang J. Du, Shyamsunder Erramilli, Pritiraj Mohanty

Materials Science

Yukawa screening derivation of the bond-valence rule

Michael L. Whittaker, Pan Wang, Chunhui Li et al. (+2 more)

The bond-valence model is a standard way to estimate bond strengths in crystals, but its exponential dependence on bond length has lacked a derivation from a specific physical interaction. We show that this form emerges as the leading-order limit of screened Coulomb electrostatics and that the fitted bond-valence softness can be interpreted in terms of an electronic screening length. This turns bond valence from an empirical fitting rule into a transferable descriptor of local screened charge response across coordination environments. The resulting theory predicts how the bond-valence parameters should vary with ionic charge and coordination number, and that prediction agrees with 150 fitted valences from 94 cation-oxygen species, including 68 in fourfold coordination and 82 in sixfold coordination, at an abundance-weighted coefficient of determination of 0.986. A comparison with first-principles charge densities shows that the bond-valence shell radius tracks the electronic screening cloud with coefficients of determination of 0.9998 for ten alkali and alkaline-earth oxides and 0.967 for 21 other binary oxides whose nearest-neighbor environments match the theory's assumptions. The widely used bond-valence model is thus the leading-order expression of screened electrostatics in ionic solids.
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All authors Michael L. Whittaker, Pan Wang, Chunhui Li, Naman Katyal, Piotr Zarzycki