Physical Review Materials

The authors have developed Bend Contour Electron Tomography (BCET), a computational framework that turns conventional electron microscope images into quantitative maps of morphology and strain tensors in ultrathin materials, which are essential for understanding and designing their mechanical, magnetic, and optical properties. Rather than scanning a sample point-by-point, BCET analyzes full-field images by decoding bend contours created as electrons scatter through a deformed crystal. Combining images acquired at different viewing angles then allows the reconstruction of both the membrane shape and its local strain. BCET offers an accessible route to efficiently mapping nanoscale deformation and, ultimately, tracking how ultrathin materials respond dynamically to light, heat, and applied forces.

This study investigates the atomic-scale structure and stability of Guinier-Preston I (GP-I) zones in Al-Zn-Mg alloys. Large-scale simulations combine molecular dynamics and Monte Carlo techniques using a newly developed atomic cluster expansion (ACE) interatomic potential. Annealing of supersaturated solid solutions leads to the formation of nearly spherical GP-I zones composed of ordered Mg-Zn building blocks, with Zn atoms frequently shifting toward interstitial positions. The resulting precipitates exhibit distinct core-shell chemistry: a Zn-rich core surrounded by an Mg-enriched interfacial region, yielding an overall Zn/Mg ratio of approximately 1.5. Simulated HAADF-STEM images reproduce key features observed experimentally. At elevated temperatures, GP-I zones preferentially dissolve rather than transform directly into more stable precipitates, while vacancies and divacancies can stabilize small solute clusters even at high temperatures.

Ultrashort laser pulses offer a route to controlling quantum coherence in atomically thin semiconductors. Using first-principles simulations, the authors investigate coherent excitonic oscillations in monolayer tungsten disulfide. They reveal how coupling between excitonic states shapes these oscillations and how an additional resonance modifies their dynamics. Building on this microscopic understanding, they propose a sequence of laser pulses that generates and regenerates coherent oscillations on demand. The results connect the microscopic physics of interacting excitons with an optical control scheme, suggesting opportunities for ultrafast optical switching and future devices that use quantum coherence to manipulate and process information in solid-state materials.

Changing the atomic composition of a semiconductor offers a powerful way to tailor its properties. This study explores atomically thin alloys of molybdenum, sulfur, and selenium by probing their excitons, Coulomb-bound electron-hole pairs. By gradually replacing selenium with sulfur, the study reveals how alloying modifies exciton emission energies, atomic lattice vibrations, spin-orbit coupling and polarization of emitted light. Combining complementary optical spectroscopy techniques with first-principles calculations, the work provides a more comprehensive understanding of how alloy composition influences excitonic behavior and its connection to electronic, vibrational, and spin-valley properties.

The authors report a comprehensive, multitechnique study of bismuth oxide growth on Au(111) under varying temperatures and oxygen exposures. Combining synchrotron-based spectroscopy, diffraction, and scanning tunneling microscopy, they elucidate the structural evolution during oxidation and annealing. Oxidation produces multiple oxide domains, including a structure consistent with the (201) surface of β-Bi${}_2$O${}_3$, while annealing drives phase separation and Au redistribution to the oxide surface. These processes induce substantial electronic modifications and lower the work function to 3.4 eV, highlighting the potential of Bi${}_2$O${}_3$ as a low-work-function interlayer for contact engineering in two-dimensional semiconductor devices.

Uncovering hidden structural dynamics in an organic conductor Organic conductors host a remarkable interplay between molecular structure and electronic properties. In \kappa-(BETS)${}_2$Mn(N(CN)${}_2$)${}_3$, a multiferroic candidate exhibiting electronic ferroelectricity below the metal-to-insulator transition at 25 K, we identify the microscopic origin of a long-standing anomaly near 100 K. Resistance noise spectroscopy, thermal expansion, and computational modeling reveal compelling evidence for a glass-like freezing of dicyanamide ligands in the anion layer. Despite occurring outside the conducting layer, this structural transition leaves a pronounced fingerprint on the charge-carrier dynamics. Our results demonstrate that slow structural fluctuations in the anion network can strongly influence electronic behavior, providing new insight into the role of donor-anion coupling and disorder in organic quantum materials.

The authors assess the performance of the recently developed non-empirical Wannier-localized, optimally tuned, screened range-separated hybrid (WOT-SRSH) functional for prototypical antiferromagnetic insulators: MnO, NiO, hematite, and chromia. By comparing WOT-SRSH with established hybrid functionals, self-consistent quasiparticle GW, dynamical mean-field theory, and available experimental data, they demonstrate its ability to offer quantitative improvement in the description of fundamental band gaps, spin magnetic moments, photoemission, and optical spectra. These results establish WOT-SRSH as a promising framework for predictive studies of the electronic, magnetic, and optical properties of magnetic insulators.

Van der Waals magnets provide a platform for exploring how reduced dimensionality, competing interactions, and local electronic degrees of freedom shape magnetic order. Here, the authors uncover hidden complexity in Ce${}_2$Te${}_5$, a layered $f$-electron ferromagnet whose apparently simple magnetic ground state masks a richer microscopic landscape. Although the system develops a single long-range ferromagnetic structure, the two inequivalent Ce sites play markedly different roles in the ordered state, and subtle magnetic changes persist well below the ordering temperature. The combination of site-selective magnetism and strong single-ion anisotropy highlights how competing interactions can produce complex low-temperature behavior without generating additional long-range magnetic phases.

Chemical short-range order (CSRO) could be contributing significantly to properties of complex FCC alloys, but signals from thermal diffuse scattering (TDS) make its measurement challenging. Here, the authors establish a generalizable connection between characteristic TDS features and phonon dispersion relations in FCC materials. Simulations in pure FCC metals are consistent with features in medium-entropy and stainless steel experimental observations confirmed with temperature dependent measurements. As a result, they can identify scenarios in which TDS interferes with CSRO characterization via electron scattering techniques, and provide several strategies to enable robust identification of CSRO.

Altermagnetic CrSb combines compensated magnetic order with a complex semimetallic electronic structure. We investigate its electrical and thermal magnetotransport in magnetic fields up to 65 Tesla, complemented by neutron diffraction and magnetization. The data reveal large nonsaturating magnetoresistance and a Hall response strongly nonlinear in magnetic field, arising from multiple electron- and hole-like carriers with mobilities approaching 3000 cm${}^2$/Vs. Mobility-spectrum analysis shows that higher fields resolve additional carrier populations hidden at lower fields. Thermal transport exhibits a similarly nonlinear field dependence and deviations from the Wiedemann–Franz law, indicating additional phononic or magnonic heat-conduction channels.