Materials Science · Cross-listed from cond-mat.supr-con
Infinite Magnetoresistance and Vortex Coupling in the Pb/BSCCO Heterostructure
Weifan Zhu, Jiamin Yao, Shuntianjiao Ling et al. (+11 more)
Combining superconductivity with spintronics provides exciting opportunities to realize low-dissipation
quantum devices. Here we report the synthesis, characterization and magnetotransport measurements of the Pb/Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (BSCCO) superconducting
heterostructures, where an insulating PbO$_{x}$ layer spontaneously forms at the interface. Non-volatile switching between superconducting (logical "0") and normal ("1") states in Pb films by an external field, i.e., infinite magnetoresistance (IMR), can be realized and are attributed to the strong trapping and pinning of
vortices in BSCCO. Furthermore, butterfly-shaped hysteresis loops in magnetoresistance, pronounced resistance dips/jumps and thermal reset to superconducting states can be observed and are direct manifestations of the peculiar
vortex dynamics in BSCCO and
vortex coupling across the Pb/BSCCO interface. Our work demonstrates a simple and effective way to realize IMR through superconducting
vortices and opens up new opportunities to study the
vortex interactions across the superconducting interfaces.
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All authors Weifan Zhu, Jiamin Yao, Shuntianjiao Ling, Shanyin Fu, Yifu Xu, Pengyue Xiong, Jiawen Zhang, Mengwei Xie, Yanan Zhang, Ye Chen, Huiqiu Yuan, Xin Lu, Qing-Hu Chen, Yang Liu
Materials Science
Atomic-scale Imaging of Iodide-Gold Interactions in Nanoconfined Liquid-Solid Interfaces
Oliver R. Waszkiewicz, Yuxiang Zhou, Baptiste Gault et al. (+3 more)
Functionalization of nanoporous metallic materials enables the tailoring of surface chemistry and morphology in nanostructured materials, optimising their performance for electrocatalytic and sensor applications.
Liquid phase chemical functionalization is governed by
liquid solid interfaces. Yet, these interfaces remain poorly understood due to the challenges of characterising the
liquid phase at high spatial and chemical resolutions. To elucidate pathways for functionalizing nanoscale metals, it is crucial to measure the distribution of species, including light elements, across the
liquid solid interface, capturing both reactants and products. Here, we employ cryogenic atom probe
tomography to directly analyse frozen
liquid solid reaction interfaces at near atomic resolution. Focusing on the interaction of iodide and sodium ions with nanoporous gold, we observe the formation of iodine containing complexes on gold nanoligament surfaces and subsurfaces. These findings reveal aspects of the gold iodide system that were previously hidden, including the reaction mechanism between iodide and gold atoms on the surface, and the multiple gold iodide complexes forming. Our work demonstrates that cryogenic atom probe
tomography can provide unprecedented visualisation and characterisation of nanoscale interfaces during chemical and electrochemical reactions, with potential implications for modern manufacturing, energy technologies, and sustainable materials development.
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All authors Oliver R. Waszkiewicz, Yuxiang Zhou, Baptiste Gault, Finn Giuliani, Mary P. Ryan, Ayman A. El-Zoka
Materials Science
Unlocking the Power of Orbital-Free Density Functional Theory to Explore the Electronic Structure Under Extreme Conditions
Cheng Ma, Qiang Xu, Zhenhao Zhang et al. (+8 more)
Recent advances in X-ray free-electron
laser diagnostics have enabled direct probing of the electronic structure under extreme pressures and temperatures, such as those encountered in
stellar interiors and inertial confinement fusion experiments, challenging theoretical models for interpreting experimental data. Kohn-Sham density functional theory (KSDFT) has been successfully applied to analyze experimental X-ray scattering measurements, but its high computational cost renders routine application impractical. Orbital-free DFT (OFDFT) is a substantially more efficient alternative, with computational cost scaling linearly with system size and a weak temperature dependence, yet it often lacks the accuracy required for electronic structure description. Overcoming this limitation, we present a non-empirical Kohn-Sham-assisted orbital-free density functional framework for calculations at extreme conditions, which enables efficient OFDFT simulations with KSDFT-level accuracy for electron densities, electron-ion structure factors, and equations of state across a broad range of conditions.
Benchmark comparisons with
quantum Monte Carlo data for dense hydrogen and validation against Rayleigh weight measurements of hot dense beryllium demonstrate the reliability of the framework and speedups of up to several hundred times compared with KSDFT. We further show that even at temperatures on the order of 100 eV,
quantum non-locality remains essential for correctly describing the electronic structure of dense hydrogen.
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All authors Cheng Ma, Qiang Xu, Zhenhao Zhang, Ke Wang, Ying Sun, Wenhui Mi, Zhandos A. Moldabekov, Tobias Dornheim, Jan Vorberger, Sebastian Schwalbe, Xuecheng Shao
Materials Science
Hydrogen at GaN(0001) surface control of Fermi level pinning: Mg activation of p-type conductivity – Nakamura process deciphered
Konrad Sakowski, Pawel Strak, Pawel Kempisty et al. (+2 more)
Ab initio calculations were used to disentangle the mystery of Nakamura activation of p-type in Mg doped MOVPE grown gallium nitride, the key process leading to the 2014 Nobel Prize in Physics. Calculations were used to obtain the
equilibrium state of the hydrogen atom deep in the GaN bulk and at the GaN(0001) surface. It was shown that the H position within bulk GaN depends on the
Fermi level: in n-type GaN, it is located in the channel, whereas in p-type GaN, it is attached to the N atom, breaking one of the GaN bonds. In contrast, at the GaN(0001) surface, H is attached in the on-top position for any hydrogen coverage; for low and high H-coverage, the
Fermi level is pinned at the Ga - broken bond state and at the valence band maximum (VBM), respectively. The
diffusion path from the bulk to the surface was obtained when the
Fermi level was high and low, the barrier was zero, and $\Delta E_{bar} \approx 1.717 eV$, which effectively blocked hydrogen escape into the vapor. Thus, high H coverage, that is, high hydrogen pressure in the vapor, prevents H from escaping from the bulk to the surface, whereas at low coverage (low hydrogen pressure), the process is barrierless. It is therefore proven that the hydrogen escape control step in the Nakamura process is the transition of hydrogen from the bulk to the surface, which is controlled by the position of the
Fermi level at the surface. Molecular hydrogen desorption from the surface is easy for high H coverage and difficult for low, thus opposite to observed experimentally thus this process is not the determining step in activation. A full thermodynamic estimate of the maximal partial pressure of hydrogen in the vapor, corresponding to the transition of the
Fermi level from the Ga-broken bond state to the VBM, was used to establish the maximal hydrogen pressure limit for the p-type Mg activation process.
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All authors Konrad Sakowski, Pawel Strak, Pawel Kempisty, Izabella Grzegory, Stanislaw Krukowski
Materials Science
Role of quasi-Fermi levels in Si- and Mg-related optical absorption in nitride laser diodes (LDs): material context
Konrad Sakowski, Cyprian Sobczak, Pawel Strak et al. (+5 more)
Optical absorption and reabsorption of light emitted from active regions in nitride
laser diodes (LDs) have been shown to reduce the light extraction efficiency of these devices. It was proven that the presence of Si and Mg may considerably increase the optical absorption. This effect is much stronger in the high-energy (short-wavelength) range of the spectrum. The absorption increase is directly related to the ionization of the Si donor and Mg acceptor levels, which are controlled by the electron and hole quasi-
Fermi levels. It is shown that the absorption may be increased because of the higher ionization of Mg caused by the compensation in the p-type region and the high ionization of Si in the n-type region. It was explained theoretically why optical efficiency is increased by removal of doping in waveguides. It was also shown that good material quality leads to a low absorption level, especially in the Mg-doped p-type part of the device.
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All authors Konrad Sakowski, Cyprian Sobczak, Pawel Strak, Izabella Grzegory, Robert Czernecki, Jacek Piechota, Agata Kaminska, Stanislaw Krukowski
Materials Science
Resolving Structural Avalanches in Amorphous Carbon with Arclength Continuation
Fraser Birks, Ibrahim Ghanem, Lars Pastewka et al. (+2 more)
Plastic deformation in amorphous solids is carried by localized shear transformations that self-organize into avalanches. In amorphous carbon modeled with a machine-learned interatomic potential, we find that the energetics and organization of these avalanches can be resolved by systematically following the underlying energy landscape. With a pseudo-arclength numerical continuation framework, we decompose avalanches into constituent shear transformations and determine their strain-dependent energetics. Our analysis shows that, prior to onset, avalanches have a latent structure that consists of well-separated local minima. We further demonstrate that arclength continuation yields an event driven framework for following avalanche dynamics, eliminating time-step effects on statistical avalanche properties such as distributions of stress drops.
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All authors Fraser Birks, Ibrahim Ghanem, Lars Pastewka, James Kermode, Maciej Buze
Materials Science · Cross-listed from stat.CO
A Framework for the Bayesian Calibration of Complex and Data-Scarce Models in Applied Sciences
Christina Schenk and Ignacio Romero
In this work, we review the theory involved in the
Bayesian calibration of complex computer models, with particular emphasis on their use for applications involving computationally expensive simulations and scarce experimental data. In the article, we present a unified framework that incorporates various
Bayesian calibration methods, including well-established approaches. Furthermore, we describe their implementation and use with a new, open-source Python library, ACBICI (A Configurable
BayesIan Calibration and Inference Package). All
algorithms are implemented with an object-oriented structure designed to be both easy to use and readily extensible. In particular, single-output and multiple-output calibration are addressed in a consistent manner. The article completes the theory and its implementation with practical recommendations for calibrating the problems of interest. These guidelines – currently unavailable in a unified form elsewhere – together with the open-source Python library, are intended to support the reliable calibration of computational codes and models commonly used in engineering and related fields. Overall, this work aims to serve both as a comprehensive review of the statistical foundations and (computational) tools required to perform such calculations, and as a practical guide to
Bayesian calibration with modern software tools.
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Materials Science · Cross-listed from cond-mat.mes-hall
Gate-tuneable single-photon emitters in WSe2 monolayer created via AFM nanoindentation on rigid SiO2/Si substrates
Ajit Kumar Dash, Sanket Jugade, Manavendra Pratap Singh et al. (+12 more)
Single-
photon emitters (SPEs) hosted by two-dimensional (2D) semiconducting materials are envisioned for next-generation
quantum applications. However, SPE creation in 2D
semiconductors on rigid substrates like SiO2/Si via nanoindentation is a technological gap, critical for interfacing SPEs with photonic
circuits and cavities. Here, we report a protocol for deterministically creating SPEs in monolayer WSe2 on SiO2/Si substrates using a sharp diamond AFM (atomic force microscope) tip. A displacement-controlled indentation process is developed, allowing indent depths > 150 nm necessary for creating SPEs. Sharp defect peaks (~200 {\mu}eV) are observed in cryogenic (4K) photoluminescence (PL) spectrum at nanoindented sites and are stable upto ~ 120K. 76% of sites exhibit sharp defect-bound peaks confirmed by power-dependent, temperature-dependent, and time-resolved PL (TRPL). AFM and PL mapping link these peaks to indent periphery. The peaks show sub-linewidth spectral jitter, no blinking, and single-
photon nature in second-order autocorrelation measurements. SPEs can be switched on/off, and background emissions suppressed using electrical gating. Gate-voltage dependent TRPL indicate that SPE dynamics can be tuned, depending on nature of SPE, pointing the way to higher-purity SPEs. Our work is directly applicable to other 2D materials and photonic
circuit/cavity compatible rigid substrates and is a significant step for scalable SPE technologies.
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All authors Ajit Kumar Dash, Sanket Jugade, Manavendra Pratap Singh, Hardeep, Tilly Guyot, Cora Crunteanu-Stanescu, Indrajeet Dhananjay Prasad, Yunus Waheed, Sumitra Shit, Sébastien Roux, Santosh Kumar, Cedric Robert, Xavier Marie, Akshay Naik, Akshay Singh
Materials Science
Fully Compensated Lines in Ferrimagnets
Qais Ali, Anna Grünebohm, Halil Ibrahim Sözen et al. (+3 more)
We generalize the classic Néel diagram and identify another type of ferrimagnetic phase that remains fully magnetically compensated below the Curie temperature, forming a continuous line of compensated points. It exhibits zero net magnetization while retaining non-relativistic, eV-scale reciprocal
spin splitting. We further find a persistently enhanced intrinsic switching field over a broad temperature range near the fully compensated phase. Proximity to the compensated line is achieved by minimizing the net local moment while balancing exchange interactions with respect to the number of equivalent atoms in each sublattice. The resulting extended Néel diagram provides practical design rules for engineering fully compensated ferrimagnetic phases via targeted chemical substitution that combines atoms with robust and weak local moments, as demonstrated through density functional theory and Monte Carlo simulations for GdCo$_5$-type ferrimagnets.
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All authors Qais Ali, Anna Grünebohm, Halil Ibrahim Sözen, Tilmann Hickel, Jörg Neugebauer, Eduardo Mendive-Tapia
Materials Science
Magnetization reversal and anisotropies in buffered transition-metal alloys thin films
Agostina Lo Giudice, Augusto Román and Laura Beatriz Steren
Interest in planar
Hall effect (PHE) sensors has re-emerged in recent years due to their promising potential for a wide range of applications, particularly in biotechnology. Sensor sensitivity can be enhanced by lowering the effective anisotropy field; however, this favors
magnetic domain formation during magnetization reversal, leading to hysteretic responses. Therefore, precise control of
magnetic anisotropy and magnetization reversal is essential to balance sensitivity and stability in PHE sensors. In this work, we investigate the
magnetic anisotropy and magnetization reversal mechanisms of Ni-Fe- and Co-Fe-based multilayers grown on various metallic buffer layers and deposited with and without an external
magnetic field, in order to evaluate the effects of the buffer layers and field-assisted deposition on the resulting
magnetic anisotropy. NiFe films exhibit a dominant uniaxial anisotropy mainly determined by the applied field during growth, with an anisotropy constant of approximately $3,\mathrm{kerg,cm^{-3}}$, largely independent of the buffer layer. In contrast, the
magnetic anisotropy of CoFe films is dominated by the buffer layer, resulting in a biaxial
magnetic response. In particular, Ag-buffered films deposited under an external
magnetic field exhibit a biaxial anisotropy with values up to $14.88,\mathrm{kerg,cm^{-3}}$. The magnetization reversal mechanism of each system was deduced from the analysis of the angular dependence of the coercive field.
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Materials Science
Ferroelectric switching at edge dislocations in BaTiO$_3$ modelled at the atomic scale
Himal Wijekoon, Pierre Hirel and Anna Grünebohm
Ferroelectric switching governs the functional properties of ferroelectric perovskites. It is widely accepted that this switching depends on domain nucleation and pinning and that these processes can be controlled by the defect structure. However, an atomistic picture of the influence of one important class of defects - dislocations on ferroelectric switching is missing. This is an important gap in knowledge as dislocations cannot be avoided at interfaces and can also be engineered by plastic deformation at high temperatures. Using atomistic simulations, we show how the cores of $\langle100\rangle$ edge dislocations in BaTiO$_3$ can either act as nucleation centers for ferroelectric switching or pin walls depending on the direction of the applied field. The coupling between electric field and polarization is strongest when the field is applied parallel to the Burgers vector of the dislocation.
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Materials Science
Long-distance spin transport in frustrated hyperkagome magnet Gd3Ga5O12
Di Chen, Bingcheng Luo, Lei Xu et al. (+17 more)
Transport of
spin angular momentum over large distance has been a long sought-after goal in the field of spintronics. While the majority of the research effort has been devoted to the
spin transport properties of magnetically ordered materials,
spin transport in magnetically frustrated materials has received little
attention. Here, we report an anomalous state in frustrated hyperkagome
magnetic insulator Gd3Ga5O12, where
spin angular momenta can be transported over a long distance of 480 {\mu}m, far exceeding the transport distance of any diffusive
spin current in magnetically ordered materials, to the best of our knowledge. Monte Carlo simulations reveal significant
spin fluctuations,
spin-
spin correlations and an absence of conventional
magnons in such anomalous state; while the response of the anomalous state to perturbation is found to be akin to an overdamped forced oscillator. We find close relation of such state to the correlated “director” state in the material. Our result provides an effective electrical technique to characterize
spin-
spin correlations and frustrations; it also unveils the potential of frustrated magnets as powerful channel materials for
spin transport.
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All authors Di Chen, Bingcheng Luo, Lei Xu, Zian Xia, Linhao Jia, Shaomian Qi, Congkuan Tian, Kangyao Chen, Hang Cui, Guangyi Chen, Shili Yan, Miaoling Huang, Jian Cui, Ya Feng, Zhentao Wang, Jiang Xiao, Jianhua Zhang, Ryuichi Shindou, X.C. Xie, Jian-Hao Chen
Materials Science
Francesco Foggetti, Francesco Cosco, Peter M. Oppeneer et al. (+4 more)
Terahertz radiation pulses can be generated efficiently through femtosecond
laser excitation of a
ferromagnetic/nonmagnetic
heterostructure, wherein an ultrafast
laser-induced
spin current results in an electromagnetic THz pulse due to
spin-charge conversion. It is, however, still poorly understood how the THz emission amplitude and its bandwidth can be optimized. Here, we perform a systematic analysis of the THz emission from various
magnetic heterostructures. The dynamics of the
spin current is described by the semiclassical, superdiffusive
spin-transport model and the energy dependence of the
spin Hall effect of hot electrons is taken into account, leading to emission profiles for Co(2 nm)/Pt(4 nm)
bilayer in good agreement with experiment. To identify the optimal {conditions} for THz emission, {we study} the properties of the emitted THz wave profile by systematically varying the layer thicknesses of metallic
bilayers, their interfacial
spin-current transmission properties, their materials' dependence, and influence of the pump
laser-pulse width, allowing us to give optimization guidelines. We find that thin nonmagnetic layer thicknesses of 5-6 nm provide the largest bandwidth in the case of Co/Pt and that the peak frequency of the THz emission depends only on the geometry of the emitter and not on the
laser pulse width. The THz bandwidth {is conversely found to} depend on several factors such as exciting
laser pulse width, layers' thicknesses, and interface transmission-reflection properties, with the limitation that an increase in the bandwidth by tuning the interface properties comes with a trade-off in the energy efficiency of the emitter. Lastly, we propose a double pulse excitation protocol of a trilayer system that could provide broadband THz emission with a large bandwidth. {Our results contribute to establishing guidelines for optimizing spintronic THz generation.
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All authors Francesco Foggetti, Francesco Cosco, Peter M. Oppeneer, Henri Jaffrés, Niloufar Nilforoushan, Juliette Mangeney, Sukhdeep Dhillon
Materials Science · Cross-listed from physics.med-ph
Combining quasi-static and high frequency experiments for the viscoelastic characterization of brain tissue
Laura Ruhland, Nina Reiter, Silvia Budday et al. (+1 more)
Mechanical models of
brain tissue are a beneficial tool to simulate neurosurgical interventions, disease progression, or
brain development. However, the accuracy and predictive capacity of such a model relies on a precise experimental characterization of the tissue's mechanical behavior. Such a characterization is yet limited by inconsistent or contradictory experimental responses reported in the literature, particularly when measurements are performed in different time or length scales. Although
brain tissue has been extensively investigated in previous studies, the combination of experimental findings from different scales has received limited
attention. In this study, we combine ex vivo mechanical responses of porcine
brain tissue obtained at different time scales in a mechanical model. We investigated the mechanical behavior of three different
brain regions in the quasi-static domain with multi-modal large strain rheometer measurements and at high frequencies with
magnetic resonance elastography (MRE). A comparative analysis of the mechanical parameters obtained from both experimental techniques demonstrated consistent regional variations in the viscoelastic behavior across the two domains. However, the mechanical behavior changes from a higher elasticity in the quasi-static and low frequency domain to a dominating viscosity at high frequencies. Based on the quasi-static and the high frequency behavior, we calibrated a fractional Kelvin-Voigt model and consequently unified the two responses in a single mechanical model to obtain a comprehensive characterization of the tissue's mechanical behavior.
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All authors Laura Ruhland, Nina Reiter, Silvia Budday, Kai Willner
Materials Science
Incorporating Gibbs free energy into interatomic potential fitting
Liangrui Wei and Yang Sun
We develop a method to fit high-temperature Gibbs free energy data for the development of interatomic potentials for atomic systems. The approach is based on
Hamiltonian thermodynamic integration, enabling the identification of suitable potential parameters such that the system's free energy matches a specified target. The method can be readily combined with conventional fitting techniques for properties such as elastic tensors and
liquid pair distribution functions. We validate the effectiveness of the approach using the Uhlenbeck-Ford model and embedded-atom method potentials for pure Ni phases and binary Fe1-xOx
liquids under high-pressure and high-temperature conditions. Our framework provides an efficient strategy for incorporating free energy into interatomic potential fitting.
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Materials Science
Turning Insulators into Accelerators: Deciphering the Interfacial Conductivity Boost in ZrO2-Li2ZrCl6 Composites through Machine Learning Molecular Dynamics Simulations
Boyuan Xu, Chen Qian, Liyi Bai et al. (+3 more)
Halide solid-state electrolytes have emerged as promising candidates for all-solid-state lithium batteries due to their high oxidative stability and deformability, yet their moderate ionic conductivity remains a bottleneck. While incorporating ionically insulating ZrO2 nanoparticles (Nat. Commun. 2023, 14, 2459) has been experimentally shown to enhance the ionic conductivity of Li2ZrCl6, the atomistic origin governing this interfacial phenomenon remains unclear. Here, we bridge the spatiotemporal gap in modeling complex
heterostructures by developing an accurate machine-learned force fields based on neuroevolution potential, enabling large-scale molecular dynamics simulations of ZrO2/Li2ZrCl6
heterostructures. By systematically investigating four representative low-
lattice-mismatch ZrO2/Li2ZrCl6 interfaces, we identify spontaneous interfacial amorphization driven by space-charge effects upon surface cleavage, trapping Li+ and leading to under-coordinated Li+ polyhedrons with pronounced
geometric distortion. These distorted amorphous interfacial regions exhibit markedly enhanced Li+ hopping activity, significantly outperforming the bulk
lattice, provided that local mobile Li+ inventory is not depleted by surface charge redistribution. This work establishes a computational framework for training validated machine-learned force fields for interfaces and provides mechanistic understandings of the interfacial conductivity boost in the
insulator-conductor composites, guiding the rational design of electrolytes toward next-generation solid-state batteries.
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All authors Boyuan Xu, Chen Qian, Liyi Bai, Chenlu Wang, Feng Ding, Qisheng Wu
Materials Science · Cross-listed from cond-mat.supr-con
Electronic Origin of Density Wave Orders in a Trilayer Nickelate
Jiangang Yang, Jun Zhan, Taimin Miao et al. (+24 more)
The discovery of superconductivity in Ruddlesden-Popper nickelates has established a new frontier in the study of high-temperature
superconductors. However, the underlying pairing mechanism and its relationship to the material's electronic and
magnetic ground states remain elusive. Since unconventional superconductivity often emerges from a complex interplay of
magnetic correlations, elucidating the
magnetic ground state of the nickelates at ambient pressure is crucial for understanding the emergence of superconductivity under high pressure. Here, we combine high-resolution angle-resolved photoemission spectroscopy with tight-binding model simulation to investigate the electronic structure of the representative trilayer Ruddlesden-Popper nickelate La$_4$Ni$_3$O$_{10}$. We provide the first experimental evidence of band splitting induced by interlayer coupling and further resolve the momentum-dependent density wave gap structures along all the
Fermi surfaces. Our findings identify the mirror-selective
Fermi surface nesting as the origin of the interlayer
antiferromagnetic spin density wave and demonstrate the dominant role of Ni-3d$_{z^2}$ orbitals in the low-energy physics of La$_4$Ni$_3$O$_{10}$. These results provide a fundamental framework for understanding the
magnetic interactions and high-temperature superconductivity mechanism in the Ruddlesden-Popper nickelate family.
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All authors Jiangang Yang, Jun Zhan, Taimin Miao, Mengwu Huo, Qichen Xu, Yinghao Li, Yuyang Xie, Bo Liang, Neng Cai, Hao Chen, Wenpei Zhu, Mingkai Xu, Shenjin Zhang, Fengfeng Zhang, Feng Yang, Zhimin Wang, Qinjun Peng, Hanqing Mao, Xintong Li, Zhihai Zhu, Guodong Liu, Zuyan Xu, Jiangping Hu, Xianxin Wu, Meng Wang, Lin Zhao, X. J. Zhou
Materials Science
Thermal and Microstructural Simulations of Photonic Sintering of Oxide Ceramics: A Two-Scale Scheme
Junlong Ma, Yangyiwei Yang, Julian N. Ebert et al. (+2 more)
Photonic sintering (PS) offers an ultra-fast, contact-free alternative to conventional sintering and has demonstrated its potential for enhancing the sinterability of acceptor-doped barium zirconate (BZY) ceramics. However, a central challenge in the PS process lies in achieving precise control over thermal self-stabilization in the presence of complex microstructural effects arising from photonic-ray–induced thermal profiles. To elucidate the interplay among thermal fields, microstructural
evolution, and PS process parameters, this study establishes a two-scale, non-isothermal simulation framework. The framework integrates macroscopic heat-transfer simulations, incorporating effective heat conduction and photonic-ray–induced volumetric heating in the porous media, with microscopic non-isothermal phase-field sintering simulations that resolve microstructure
evolution under local thermal profile. Scale bridging is achieved through a temperature field transferring and mapping that satisfies Hill-Mandel condition between the macroscopic and microscopic simulations, while maintaining synchronization between their asynchronous time-stepping schemes. After calibrating model parameters against experimental measurements, the framework successfully reproduces the experimentally observed porosity inhomogeneity along the sample depth. The influence of enhanced localized mass transport is further examined through a parametric investigation of surface and grain boundary diffusivities. Overall, the proposed framework demonstrates its feasibility and physical interpretability in establishing process-microstructure relationships for the scalable fabrication of high-performance protonic ceramics.
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All authors Junlong Ma, Yangyiwei Yang, Julian N. Ebert, Wolfgang Rheinheimer, Bai-Xiang Xu
Materials Science · Cross-listed from cond-mat.str-el
Electronic band structure, phonon dispersion, and magnetic triple-q state in GdGaI
Tatsuya Kaneko, Ryota Mizuno, Shu Kamiyama et al. (+2 more)
We theoretically investigate the physical properties of the
magnetic van der Waals material GdGaI. Using first-principles calculations, we compute the
phonon dispersion of GdGaI and show no imaginary
phonons, suggesting that
phonon-driven phase transitions are unlikely to occur in GdGaI. Our band calculation reveals that the electronic bands near the
Fermi energy are composed of Gd 5d and Ga 4p orbitals. We construct a tight-binding model that incorporates the Gd 5d and Ga 4p orbitals to investigate the
magnetic structure. We introduce Kondo coupling between electrons in Gd 5d orbitals and localized
spins in Gd 4f orbitals and present the modified band structure when localized
spins form a
magnetic order characterized by three q vectors that connect the valence and conduction bands. We discuss the origin of the
spin order based on the Ruderman-Kittel-Kasuya-Yosida mechanism and suggest that Coulomb interactions acting on electrons near the
Fermi level can contribute to the ordering of localized
spins.
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All authors Tatsuya Kaneko, Ryota Mizuno, Shu Kamiyama, Hideo Miyamoto, Masayuki Ochi
Materials Science
Synthesis of Monolayer Ice on a Hydrophobic Metal Surface
Qiaoxiao Zhao, Meiling Xu, Dong Li et al. (+10 more)
Understanding water-metal interactions is central to disciplines spanning catalysis, electrochemistry, and atmospheric science. Monolayer ice phases are well established on hydrophilic surfaces, where strong water-substrate interactions stabilize ordered hydrogen-bond networks. In contrast, their formation on hydrophobic metals has been deemed ther-modynamically unfavourable, with water typically assembling into amorphous films, three-dimensional crystallites, or interlocked
bilayer ice. Here, we demonstrate the synthesis of a monolayer ice phase on the hydrophobic Au(111) surface using a low-energy-electron-assisted growth method. Combined experimental characterizations including low-energy electron diffraction, angle-resolved photoemission spectroscopy, and X-ray photoelectron spectroscopy, complemented by first-principles calculations, prove that the monolayer ice phase composes of intact water molecules. This approach provides a generalizable strategy for stabilizing ordered two-dimensional ice on inert substrates and offers new insight into the interplay between water and low-energy electrons at hydrophobic interfaces.
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All authors Qiaoxiao Zhao, Meiling Xu, Dong Li, Zhicheng Gao, Yudian Zhou, Wenbo Liu, Jingyan Chen, Peng Cheng, Sheng Meng, Kehui Wu, Yanchao Wang, Lan Chen, Baojie Feng