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Modern processors integrate heterogeneous devices to expose unified shared memory. Yet, the de-facto design pattern used to compose their disparate coherence protocols lacks a formal foundation. This leaves the door open for subtle consistency bugs, in a critical gap between practice and correctness. This paper provides the first formal, machine-checked proof that a de-facto design pattern, which we call the Principle of Synchronous Propagation, is correct. Leveraging a new unifying abstraction for coherence protocols, our central theorem (machine checked in Lean) proves that Synchronous Propagation is sufficient to guarantee the Compound Memory Consistency Model for a wide class of protocols. Our work provides long-needed assurance for current designs and delivers a reusable, compositional framework for verifying future heterogeneous systems. 

The mechanical behavior of semiconductors is critical to the reliability of microelectronic, power, photonic, and sensing devices, notably under multiphysical stimuli, e.g., light illumination and stress. Zinc sulfide (ZnS), a prototype II–VI semiconductor, exhibits a positive photoplastic effect, with an increased strength and reduced plastic deformability under light illumination. Yet, the atomistic mechanisms behind such light-induced mechanical modulation remain not well understood. In this study, we perform molecular dynamics simulations with machine-learned force fields to investigate the deformation behavior of ZnS nanopillars under both dark and illuminated conditions. Three representative crystallographic orientations ([001], [1-10], [111]) are considered to understand the plastic anisotropy in it. Our simulation results reveal that phase transformation, rather than dislocation glide, dominates the plastic flow in ZnS under deformation along [001] direction. In contrast, the shear banding-induced brittle failure occurs when ZnS is compressed along two other directions ([1-10] and [111]). Under light illumination, the yield stress of ZnS increases by at least 4.2% across all the three orientations, but with different mechanisms underlying them. In detail, when the sample is compressed along [001] direction, the strength enhancement arises primarily because photoexcited charge carriers delay the phase transformation. Instead, when the sample is deformed along [1-10] and [111] directions, the yielding strength is enhanced because illumination suppresses shear localization and delays failure initiation in the brittle failure orientations. This work provides atomistic insight into how illumination modulates the plastic flow in ZnS under deformation. 

Zirconium carbide (ZrC), a high‐performance refractory ceramic, exhibits complex defect dynamics that critically influence its behavior in extreme environments. In this work, we employ density functional theory (DFT) simulations to determine the formation energies and migration barriers of four defect types—isolated carbon vacancies, divacancies, Frenkel pairs, and Schottky pairs—across various charge states. The calculated formation energies reveal that isolated carbon vacancies are the most energetically favorable (1.13 eV), followed by Frenkel pairs (3.29 eV), while divacancies (6.86 eV) and Schottky pairs (8.29 eV) require higher formation energies, indicating their lower intrinsic concentrations. Isolated carbon vacancies exhibit the highest migration barrier (4.11 eV) in ZrC, with a modest increase to 4.13 eV upon adding one electron to 64‐atom supercell and a decrease to 4.06 eV with two electrons/64‐atom supercell—reflecting charge redistribution that stabilizes the local environment and weakens nearby Zr–C bonds. In contrast, Frenkel and Schottky pairs show barrier increases with electron doping and decreases with holes (ranging from 3.26 to 3.44 eV and 3.37 to 3.73 eV, respectively), while divacancies display increases (carbon vacancies: 2.69 to 2.93 eV; zirconium vacancies: 3.60 to 3.69 eV) upon electron addition. These results reveal the defect‐specific impact of charge carriers on mobility in ZrC, offering key insights for optimizing its performance in extreme environments. 

Photo-plasticity in semiconductors, wherein their mechanical properties such as strength, hardness, toughness, and ductility are influenced by light, has been reported for several decades. Although such phenomena have drawn significant attention to the manufacturability of deformable semiconductor devices, their underlying mechanisms are not well understood due to the lack of direct evidence. Here we provide experimental observation and atomic insights into the reduced mobility of dislocations in zinc sulfide (ZnS), as a model material, under light. Using photo-nanoindentation and transmission electron microscopy, we observe that dislocations glide shorter distances under light than in darkness, and there are no apparent deformation twins in both conditions. By atomic-scale simulations, we demonstrate that the decreased dislocation mobility is attributed to the increased Peierls stress and enhanced stress fields around dislocation cores due to photoexcitation. This study improves the understanding of photo-plastic effects in inorganic semiconductors, offering opportunities for modulating their mechanical and related functional properties using light. 

Inorganic semiconductors exhibit photoplasticity, where light exposure alters dislocation-mediated plastic flow based on the material’s bonding character and carrier–defect interactions. In ionic II–VI compounds (e.g. ZnS and ZnO), above-band-gap illumination generates electron–hole pairs that are readily trapped at dislocation cores. This increases the Peierls stress (the effective barrier to glide), causing photoplastic hardening or a positive photoplastic effect. In contrast, covalent semiconductors (e.g. GaP, GaAs, Ge, and Si) demonstrate softening under illumination (negative photoplasticity) since photoexcited carriers often facilitate dislocation glide and reduce flow stress. This review summarizes recent experimental and theoretical progress on photoplasticity in inorganic semiconductors and integrates these results into a unified microscopic framework. Here, we discuss how modern techniques, density functional theory (DFT), constrained DFT, machine learning interatomic potentials, and largescale molecular dynamics (MD) directly connect electronic excitation to changes in generalized stacking-fault energy surfaces, dislocation core reconstruction, and mobilities. On the experimental side, we review in situ mechanical tests under controlled illumination—from bulk compression to photonanoindentation and transmission electron microscopy—that directly show how light modulates dislocation activity. By systematically comparing ionic II–VI and covalent III–V/group-IV systems, we identify the key mechanisms that control the sign and magnitude of photoplasticity and outline design principles for semiconductors whose mechanical properties can be actively tuned by light illumination. 

Photoplasticity, the light-induced alteration of mechanical properties in semiconductors, is crucial for the development of advanced optoelectronic devices and the understanding of semiconductor mechanics. Despite progress in understanding this phenomenon, atomic-scale mechanisms, particularly under photoexcitation, remain complex and are partially understood. Here, we introduce a new computational framework combining constrained Density Functional Theory (CDFT) with machine learning potential (MLP) to explore Peierls stress and dislocation dynamics in zinc sulfide (ZnS) under both ground and excited states. Our results reveal that photoexcitation significantly increases Peierls stress by reducing strain concentration at the dislocation core, contributing to the transition from ductility to brittleness under light exposure. Importantly, this enhancement occurs without substantial changes in the dislocation core structure. These insights provide an understanding of the atomic-scale mechanisms behind photoplasticity in ZnS, demonstrating that integrating CDFT with MLP is a highly accurate and efficient approach to study complex material behaviors under photoexcitation. 

Doping in semiconductors not only modulates their electrical properties but also influences their mechanical behavior, such as nanoindentation pop-in phenomena. However, the underlying mechanisms of how doping affects pop-in events remain under debate. Here, we report the opposite effects of doping on the nanoindentation pop-in phenomena in InAs and Ge using nanoindentation, atomic force microscopy (AFM), and density functional theory (DFT) calculations. For InAs, the pop-in events disappear after doping with Zn and S, due to a reduction in energy barriers for dislocation nucleation, as revealed by the comparison of γ-surface energy. In contrast, pronounced pop-in events appear in Ge after doping with Ga and Sb, indicating an increase in stored elastic energy before phase transition in Ge. This research enhances our understanding of doping effects on the onset of plastic deformation, offering insights into the connection between the electronic structures and mechanical properties of semiconductors.