Electron's orbital degrees of freedom are a crucial attribute of solids as it influences many fundamental properties of materials through spin–orbit coupling and crystal field-mediated coupling to lattice. The successful control and manipulation of spin states in solid-state systems through electron orbital angular momentum (OAM) following recent theoretical predictions has triggered an upsurge of research activities to attain enhanced functionality and efficiency in devices. This new approach, known as “orbitronics,” explores the use of OAM for information processing and storage, potentially offering significant advantages over traditional spintronics by harnessing the orbital degrees of freedom. In particular, the dynamics of OAM transport within ferromagnets is fundamentally different from that of its spin counterpart and propagates over a longer length scale than the spin dephasing length enabling long-range high-density information transmission. The advancements in the field from the fundamental understanding of OAM generation to the latest orbital-charge current interconversion techniques and long-range OAM dynamics within materials is meticulously reviewed here with insights from “orbital pumping” and Terahertz experiments. Subsequently, the recently proposed concept of exploiting OAM via orbital angular position for orbital current generation, a qualitatively different approach compared to spin angular momentum, is also introduced.

Black-box optimization (BBO) is used in materials design, drug discovery, and hyperparameter tuning in machine learning. The world is experiencing several of these problems. In this review, a factorization machine with quantum annealing or with quadratic-optimization annealing (FMQA) algorithm to realize fast computations of BBO using Ising machines (IMs) is discussed. The FMQA algorithm uses a factorization machine (FM) as a surrogate model for BBO. The FM model can be directly transformed into a quadratic unconstrained binary optimization model that can be solved using IMs. This makes it possible to optimize the acquisition function in BBO, which is a difficult task using conventional methods without IMs. Consequently, it has the advantage of handling large BBO problems. To be able to perform BBO with the FMQA algorithm immediately, we introduce the FMQA algorithm along with Python packages to run it. In addition, we review examples of applications of the FMQA algorithm in various fields, including physics, chemistry, materials science, and social sciences. These successful examples include binary and integer optimization problems, as well as more general optimization problems involving graphs, networks, and strings, using a binary variational autoencoder. We believe that BBO using the FMQA algorithm will become a key technology in IMs, including quantum annealers.

Thermoelectric conversion through the Nernst effect holds great promise for energy-harvesting scenarios. Typically, the applied thermal gradient, magnetic field and the generated voltage V are mutually orthogonal to induce a B-linear out-of-plane Nernst effect. Here, we show that this restriction can be lifted by engineering proper crystal orientation in RuO2 films. While RuO2 (100) and RuO2 (110) are consistent with normal circumstances, we observe a B-linear planar Nernst effect (LPNE) in RuO2 (101). This is attributed to the low symmetry RuO2 (101) crystal lattice that allows for a non-zero off-diagonal component in the Nernst coefficient tensor. In addition, we find that the magnitude for the LPNE is stable across the temperature range of 60–280 K, with fluctuation <±13.5%, which surpasses the temperature stability for conventional Nernst effects. Our work advances the understanding of crystal symmetry-modulated thermoelectric phenomenon, providing a feasible approach to manipulate the Nernst effects.

Twist-angle engineering in van der Waals homo- and hetero-bilayers introduces profound modifications in their electronic, optical, and mechanical properties due to lattice reconstruction. In these systems, the interlayer coupling and atomic rearrangement strongly depend on the twist angle, leading to the formation of periodic moiré superlattices. At small twist angles, significant lattice relaxation results in the emergence of domain structures separated by one-dimensional (1D) soliton networks, influencing electronic band structures and phonon modes. In this study, we systematically investigate the impact of lattice reconstruction on phonon renormalization in twisted bilayer graphene (TBLG) and graphene-hBN moiré superlattices, representing homo- and hetero-bilayer system, respectively. Using Raman spectroscopy, we identify distinct phonon behaviors across different twist angle regimes. In TBLG, we observe the evolution of the G peak, including broadening, splitting, and the emergence of additional peaks in the small angle range (0.3°−1°), attributed to moiré-modified phonon interactions. At large twist angles, the peaks gradually merge back into a single feature, reflecting the reduced impact of lattice reconstruction. Similarly, in hBN–graphene moiré superlattices, we detect moiré-induced Raman peaks above and below the G peak, while the central G peak remains largely invariant to twist angle variation. The theoretical calculations based on classical force-field uncover moiré phonon modes originating from different stacking regions, including AB (AB′), AA, and SP configurations, providing insights into phonon renormalization driven by lattice reconstruction. Our results establish a direct link between twist angle, lattice reconstruction, moiré phonons, and interlayer coupling, offering a fundamental framework for understanding phonon engineering in twisted bilayer systems. These findings pave the way for controlling phononic, optoelectronic, and heat flow properties in next generation van der Waals heterostructures.

As Moore's law approaches its physical limits, the development of alternative high-speed, low-energy information technologies based on post-silicon advanced materials has become increasingly imperative. Two-dimensional (2D) ferroic materials, especially involving ferromagnetic, ferroelectric, and their coupling systems, have recently emerged as a frontier research focus in condensed matter physics and materials science. These materials offer unique physical properties and demonstrate tremendous potential for applications in next-generation high-density, low-power information devices. This work provides an overview from ferroic mechanisms to ferroic manipulating strategies and their various applications, demonstrating recently important progress. We emphasized the challenges faced in the scarcity of these intrinsic 2D ferroics, especially for ferromagnetic–ferroelectric materials, point out the potential ways to expand the 2D ferroics source, and offer an artificial intelligence-empowered paradigm roadmap for accelerating their exploration.

Violet phosphorus (VP), a recently identified two-dimensional (2D) allotrope of phosphorus, exhibits a range of distinctive properties that position it as a promising material for diverse advanced applications. This review begins with a detailed examination of the synthesis strategies for VP, including bulk-phase growth, few-layer exfoliation, and the fabrication of VP quantum dots (QDs). Each method's advantages, limitations, and impact on the material's structural and electronic properties are discussed. VP's unique characteristics, such as its tunable direct bandgap, high charge carrier mobility, and anisotropic behavior, enable strong performance in optoelectronics. Applications in polarization-sensitive photodetectors, broadband photodetection, and neuromorphic vision systems are critically reviewed, emphasizing its potential for next-generation photonic devices. In the biomedical domain, VP's biodegradability, tunable optical properties, and promising electronic characteristics provide opportunities for biosensing, antibacterial treatments, and cancer therapy. Finally, VP's potential for energy storage and conversion is explored, with particular attention given to its role in photocatalytic hydrogen evolution and as an anode material in sodium-ion and lithium-ion batteries. The review provides a comprehensive analysis of VP's synthesis, properties, and multifaceted applications, while highlighting the ongoing challenges and future research directions required to fully exploit its potential.

Copper metasilicate (CuSiO3) derived from mineral dioptase is a unique anisotropic compound with planar edge-sharing CuO4+2 “octahedra” interspaced by SiO4 tetrahedra running along [001] direction. Combined with multivalent Cu sites and Si, it provides a robust structure for electrocatalytic CO2 reduction (ECR) reactions. Unlike metallic Cu, widely studied for ECR initially, Cu-based materials have drawn more attention lately as they not only exhibit selective formation of products due to the presence of Cuδ+ (1 < δ < 2) sites, but also ensure structural stability. Herein, we study the electronic structure of the novel orthorhombic CuSiO3 in bulk, [100] and [020] surfaces. We then investigate stepwise ECR on the [100] surface of CuSiO3 due to its appropriate alignment of d-band center, suitable chemical structure, and active surface atoms. Furthermore, the spin-polarized studies show [100] planes of CuSiO3 are half-metallic and promising for ECR. The detailed analysis of various parallel reaction pathways of ECR and the calculated free energies shows that *CHO formation is the potential-determining step with an energy barrier of 0.58 eV. ECR investigation indicates that the most feasible CO2→CH3OH conversion occurs with the on-site magnetic moment (μB) ≈0.2 for Cu atoms, and the changes in Gibbs free energies are closely related to the variations of on-site μB of Cu atoms on CuSiO3 [100]. We studied how the Cu–O–Si interaction affects the reaction pathways, influencing formation of specific reaction intermediates, thereby leading to the most probable products. Due to the presence of abundant active surface sites with varying oxidation states, and higher conductivity, CuSiO3100 exhibits a reduced activation barrier and a favorable CO2 reduction to CH3OH.

Ferroelectric materials are poised to drive the next technological leap through their emergent functionalities, including negative capacitance and resistance, charge accumulation without transport, and spontaneous polarization switching. The discovery of ferroionic material-systems that combine room-temperature ferroelectricity and fast ionic conductivity has opened an unprecedented avenue for multifunctional devices that merge the territories of electronics and ionics. These hybrid materials enable the direct coupling of ionic and electronic order parameters, allowing long-range electrostatic interactions, wireless field communication, and energy transduction across solid–solid and solid–air interfaces. Such capabilities offer potential solutions to long-standing challenges, including the Boltzmann limit in transistor subthreshold operation, voltage amplification without power dissipation, and nonvolatile polarization states with ionic reconfigurability. Beyond conventional applications, ferroionics support a new generation of quantum sensors and adaptive devices, spanning optical, electrical, mechanical, thermal, and magnetic domains. This review provides a comprehensive overview of the conceptual foundations, theoretical frameworks, and experimental progress underlying ferroionic systems, highlighting their role as a bridge between ferroelectrics, solid electrolytes, and correlated quantum materials. Finally, perspectives are offered on how ferroionic coupling may reshape device physics and enable sustainable, self-powered information and energy technologies.

It has long been thought that the reversed Cherenkov radiation is impossible in homogeneous media with a positive refractive index n. Here, we break this long-held belief by revealing the possibility of creating reversed Cherenkov radiation from homogeneous positive-index moving media. The underlying mechanism is essentially related to the Fizeau–Fresnel drag effect, which provides a unique route to drag the emitted light in the direction of the moving medium and thus enables the possibility of dragging the emitted light in the opposite direction of the moving charged particle. Moreover, we discover the existence of a threshold for the velocity vmedium of moving media, only above which, namely, vmedium>c/n2, the reversed Cherenkov radiation may emerge, where c is the velocity of light in vacuum. Particularly, we find that the reversed Cherenkov radiation inside superluminal moving media (i.e., vmedium>c/n) can become thresholdless for the velocity of moving charged particles.

Crystalline silicon (c-Si) photovoltaics dominate the solar industry, yet further advancements hinge on passivating and carrier-selective contacts to overcome efficiency limitations. This review explores the pivotal role of atomic layer deposition (ALD) in enabling metal oxide films for high-performance c-Si solar cells, bridging material innovation with industrial scalability. Historically, ALD-grown Al2O3 enabled the effective passivation of p-type Si surfaces via its high negative fixed charge, which made localized rear contacts viable and facilitated the transition from aluminum back surface field to passivated emitter rear contact architectures, ultimately lowering J0 and boosting efficiency. However, emerging carrier-selective contacts demand materials that simultaneously minimize recombination and resistive losses while avoiding parasitic absorption. Metal oxides, leveraging tunable optoelectronic properties and ALD's atomic-scale precision, offer a promising alternative to conventional silicon-based films (e.g., a-Si:H and poly-Si). We analyzed 373 studies to map trends in ALD metal oxide applications, highlighting the dominance of Al2O3 and TiO2, alongside growing interest in multi-metal oxides. The review underscores ALD's unique ability to tailor chemical and field-effect passivation mechanisms while addressing challenges in stoichiometric control and interfacial engineering. Targeting both ALD specialists and PV engineers, we propose standardized metrics for evaluating passivating contacts, aiming to accelerate cross-disciplinary innovation. Finally, we outline future opportunities for ALD-derived metal oxide in next-generation photovoltaics, including tandem and thin-film technologies, advocating for systematic research to unlock their full potential.