Abstract The Rashba effect, originating from spin-orbit interaction and crystal asymmetry, enables electric-field control of electron spins, making materials with strong Rashba splitting near the Fermi level attractive for spintronics. Using first-principles calculations, we identify asymmetric Bi 2 O 2 Se monolayer as a semiconductor exhibiting large Rashba splitting. Its structure induces a work function difference (Δ ϕ ) of 3.25 eV, dipole moment of 0.32 D, and a small band gap of 0.30 eV. The conduction band shows Rashba energy E R = 33.6 meV and coupling constant α R = 10.56 eV Å with circular spin texture around the Γ point. The monolayer remains mechanically stable under ± 10% strain, while strain and electric fields (≤0.3 V/Å) reversibly tune polarization and Rashba splitting. A finite out-of-plane spin component ( S z ) emerges from anisotropic SOC, demonstrating experimentally feasible and controllable spin-texture modulation. Both E R and α R increase under tensile strain, highlighting Bi 2 O 2 Se’s potential for high-efficiency spin-field-effect transistors and advanced semiconductor spintronics.

Abstract Polytypism in transition metal dichalcogenides (TMDs) introduces an additional degree of freedom for tailoring the electronic properties of layered van der Waals materials. Polytypes with larger unit cells, spanning four or six layers, can be viewed as natural homostructures, since their atomic composition remains identical across the layers. The resultant crystalline environments can potentially give rise to exotic electronic states, earning these materials recent attention. In this study, we examine structural and charge transport properties of metallic and superconducting 4H a -NbSe 2 . We find that the compound has a highly disordered stacking of layers, which impedes interlayer coherence, as demonstrated by detailed out-of-plane resistivity measurements, and effectively tunes the bulk system towards an atomically thin limit. The disordered structure largely accounts for the enhanced resistivity anisotropy and superconducting upper critical field, when compared to 2H a -NbSe 2 . This phenomenon can be exploited to promote quasi-two-dimensional physics in bulk crystals, and our study also underscores the importance of thorough structural characterization when investigating large-unit-cell polytypes of TMDs.

Abstract The performance of solution-processed 2D material networks is typically limited by intersheet junctions, which disrupt charge transport and prevent intrinsic nanosheet properties from scaling. Advances in processing and characterisation now allow direct junction engineering to tune the interlayer transport mechanisms. This Perspective reviews the current understanding of junctions, techniques for measuring their properties, and discusses engineering strategies for their tuning, aiming to unlock scalable fabrication of high-performance devices that mirror intrinsic 2D material properties.

Abstract Altermagnetic materials combine compensated magnetic order with momentum-dependent spin splitting, offering a fundamentally new route for spintronic functionality beyond conventional ferromagnets and antiferromagnets. While most studies have focused on three-dimensional compounds, the emergence of altermagnetism in few-layer two-dimensional materials remains largely unexplored. Here, we demonstrate that bilayer MnPS 3 , a prototypical 2D van der Waals magnet, can host stacking-induced altermagnetic phases. Using density-functional theory and spin-Laue symmetry analysis, we show that interlayer spin alignment and lateral displacement act as coupled symmetry control parameters that switch the system between Type II (collinear AFM) and Type III (altermagnetic) phases. These results establish stacking engineering as a powerful, purely structural route for designing tunable altermagnetic states in 2D magnets, opening pathways toward symmetry-driven spintronic and magnetoelectronic devices.

Abstract Zero-dimensional potential wells and potential walls exist in nanoscale devices, trapping, scattering or blocking charge carriers. Measuring these quantum perturbations during normal operation is notoriously difficult. We address this challenge using trap-emission currents in multilayer Cr-MoSe 2 -Pd devices and interpreting them with density-functional-theory simulations. Sulfur passivation removes electron traps while hole transport remains unchanged, confirming hole capture originates from valence-band offsets at metal/TMD interfaces. When a 70 kV/cm lateral field is applied, tensile strain forms in the channel, lowering electron-trap activation energies and reconfiguring electron-trapping centers, yet hole traps remain stable. By separating defect-governed trapping in the channel from energy-barrier trapping at contacts, we deliver a comprehensive framework for mapping perturbations in low-dimensional electronic landscapes due to realistic operation. This methodology enables targeted passivation and strain engineering to build quantum-confined devices whose carrier dynamics-and therefore performance-remain predictable and robust across operating conditions and material systems, advancing technologies and applications.

Abstract Moiré superlattices formed in twisted two-dimensional (2D) materials provide a highly tunable platform to investigate strongly correlated quantum phenomena. Recent advances have revealed a rich landscape of interaction-driven phases, including correlated insulators, superconductivity, magnetism, and fractional topological states, many of which are inaccessible in conventional materials. This review provides an overview of moiré-induced quantum phases, focusing on their underlying mechanisms and recent progress toward zero-magnetic-field fractional states. We aim to provide an integrated perspective bridging fundamental physics and potential applications in quantum electronics.