Twisted multilayers of two-dimensional materials attract widespread research interest due to their intriguing electronic and optical properties related to their chiral symmetry breaking and moir & eacute; effects. The two-dimensional transition metal dichalcogenide MoSe2 is a particularly promising material for twisted multilayers, capable of sustaining moir & eacute; excitons. Here, we report on a rational bottom-up synthesis approach for twisted MoSe2 flakes by chemical vapor transport (CVT). Screw dislocation-driven growth was forced by surface-fused SiO2 nanoparticles on the substrates that serve as potential nucleation points in low supersaturation condition. Thus, crystal growth by in-situ CVT under addition of MoCl5 leads to bulk 2H-MoSe2 in a temperature gradient from 900 to 820 degrees C with a dwell time of 96 h. Hexagonally shaped 2H-MoSe2 flakes were grown from 710 to 685 degrees C with a dwell time of 30 min on SiO2@Al2O3(0001) substrates. Electron backscatter diffraction as well as electron microscopy reveals the screw dislocation-driven growth of triangular 3R-MoSe2 with individual step heights between 0.9 and 2.9 nm on SiO2@Si(100) under the same conditions. Finally, twisted MoSe2 flakes exhibiting a twist angle of 19 degrees with respect to the [010] zone axis could be synthesized.

ABSTRACT Low‐temperature atomic layer deposition (ALD) is increasingly important for the integration of layered metal dichalcogenides such as tin diselenide (SnSe 2 ) into advanced nanoelectronic devices, where compatibility with temperature‐sensitive substrates and precise thickness control are essential. Using a novel and highly reactive selenium precursor, namely, bis(trimethylstannyl)selenide or Se(SnMe 3 ) 2 , SnSe 2 films are deposited at reduced temperatures. As‐deposited films are initially amorphous, however, post‐deposition annealing at 250°C induces crystallization. Structural analysis reveals a clear evolution in crystallinity: ultrathin films (∼25 nm) exhibit nearly single‐crystalline, defect‐free domains, while thicker films (∼100 nm) transition to a polycrystalline structure. This controlled variation in crystal quality directly influences the electronic transport properties, demonstrating the potential of low‐temperature ALD combined with mild annealing for scalable fabrication of high‐performance, thickness‐engineered SnSe 2 ‐based devices.

Quantum confinement in artificial superlattices enables the engineering of electronic and optical properties that exceed bulk limitations. Despite the unrivaled precision in thickness control and scalability of atomic layer deposition (ALD), the experimental demonstration of confinement effects in the superlattice geometry has remained elusive, especially for nonoxide systems. In this study, we report the experimental demonstration of distinct quantum confinement in the chalcogenide-based heteromorphic superlattices via an ALD supercycle approach. Polycrystalline PbS and amorphous SnS2 are alternately deposited with subnanometer thickness control, resulting in the formation of a well-defined heteromorphic superlattice structure with sharp, strain-relieved, and defect-passivated interfaces. Raman spectroscopy also revealed the activation of low-frequency vibrational modes, indicating strong interlayer coupling of strain-free layers within the superlattice. A systematic reduction in the PbS sublayer thickness below its excitonic Bohr radius enables a substantial and controllable widening of the bandgap, from 1.74 eV for PbS (14 nm)/SnS2 (5 nm) to 2.51 eV for PbS (3 nm)/SnS2 (5 nm), compared to 1.54 eV for individually grown PbS films. This marked bandgap modulation unambiguously demonstrates the strong quantum confinement of charge carriers within the strain-relaxed PbS layers. Density functional theory (DFT) calculations confirm the experimental observations, revealing the emergence of both lateral and vertical quantum confinement and elucidating the role of the superlattice architecture in shaping the electronic structure. Together, these results establish ALD as an effective platform for quantum superlattice engineering, enabling precise control of confinement effects in complex chalcogenide heterostructures and their integration into next-generation optoelectronics and quantum devices.

Abstract Multilayer thin film structuring offers a versatile strategy to tailor nanostructures through interface engineering. Atomic layer deposition (ALD) provides precise control of composition and structure via supercycle approaches that enable the multiple metal species introduction. However, the resulting growth behavior is often interpreted without fully accounting for interfacial effects that govern nucleation and nanostructure evolution. In this work, we demonstrate that introducing SnSe2 layers into Sb2Te3/SnSe2 multilayer films using ALD supercycle significantly enhances Sb2Te3 nucleation and accelerates out-of-plane growth, leading to an increase in growth per cycle (GPC) from 0.18 to 0.69 Å/cycle. First-principles atomistic simulations of precursor deposition chemistry and extremely surface-sensitive low-energy ion scattering (LEIS) analysis confirm the promoted growth of Sb2Te3 in Sb2Te3/SnSe2 multilayer structures, which is also accompanied by elemental exchange reactions between Te and Se atoms. The resulting Sb2Te3/SnSe2 multilayer thin films exhibit increased charge carrier and phonon scattering, leading to a significant reduction in lattice thermal conductivity from 1.09 to 0.25 W/mK at room temperature due to the modulated nanostructure. This study establishes a robust analytical framework for understanding and engineering interfacial reactions and nucleation phenomena in ALD-based multilayer systems.

Magnetic materials with strong spin-orbit coupling (SOC) are essential for the advancement of spin-orbitronic devices, as they enable efficient spin-charge conversion, complex magnetic structures, spin-valley physics, topological phases and other exotic phenomena. 5d transition-metal oxides such as SrIrO3 feature large SOC, but usually show paramagnetic behavior due to broad bands and a low density of states at the Fermi level, accompanied by a relatively low Coulomb repulsion. Here, we unveil ferromagnetism in 5d SrIrO3 thin films grown on SrTiO3 (111). Through substrate-induced structural engineering, a zigzag stacking of three-unit-cell thick layers along the [111] direction is achieved, stabilizing a ferromagnetic state at the interfaces. Magnetotransport measurements reveal an anomalous Hall effect below similar to 30 K and hysteresis in the Hall conductivity below 7 K, indicating ferromagnetic ordering. X-ray magnetic circular dichroism further supports these results. Theoretical analysis suggests that the structural engineering of the IrO6 octahedral network enhances the density of states at the Fermi level and thus stabilizes Stoner ferromagnetism. This work highlights the potential of structurally engineered 5d oxides for spin-orbitronic devices, where efficient control of SOC-induced magnetic phases by electric currents can lead to lower energy consumption and improved performance in next-generation device technologies.

Two-dimensional (2D) TaS2 has emerged as a compelling platform for investigating collective electronic phenomena, particularly due to its intricate charge density wave (CDW) phases. To probe nanoscale CDW behavior and superconductivity, the synthesis of high-quality 1T-TaS2 nanocrystals (NCs) is required. In this work, we report for the first time the optimized synthesis of highly crystalline 1T-TaS2 NCs via a thermodynamically optimized chemical vapor transport approach. A comprehensive investigation was conducted to evaluate the influence of key growth parameters, including substrate type (SiO2/Si, c-sapphire, and mica), substrate temperature, growth duration, and transport agent concentration on the resulting crystal morphology and lateral dimensions. Various techniques have been employed to characterize the produced NCs including optical microscopy (OM), atomic force microscopy (AFM), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). Our findings highlight the critical role of the substrate in the growth dynamics and provide a versatile platform for controlled synthesis of the 1T-TaS2 phase, paving the way for its integration into next-generation electronic and quantum technologies.

Curvilinear magnetic nanostructures enable control of magnetization dynamics through geometry-induced anisotropy and chiral interactions, as well as magnetic field modulation. In this work, we report a curvilinear magnonic crystal based on large-area square arrays of truncated nanospikes fabricated by conformal coating of 3D hierarchical templates with permalloy thin films. Brillouin light scattering spectroscopy reveals an anisotropic band structure with multiple dispersive and folded Bloch-type dispersive spin-wave modes as well as nondispersive modes exhibiting direction-dependent frequency shifts and intensity asymmetries along lattice principal axes. Finite element micromagnetic simulations indicate that curvature-induced variations of the demagnetizing field govern the magnonic response, enabling the identification of modes propagating in nanochannels and others localized on nanospike apexes or along the ridges connecting adjacent nanospikes. The combination of geometric curvature and optical probing asymmetry produces directional dependence of magnonic bands, establishing 3D hierarchical templates as a versatile platform for curvature-engineered magnonics.

Bloch points are three-dimensional topological singularities in magnetization that play a key role in topological transformations of spin textures, such as skyrmion creation or annihilation. While topology often enforces the existence of Bloch points in confined geometries like cylindrical nanowires, deterministic control over their position and magnetic configuration remains challenging. Here we demonstrate the generation of Bloch points with controlled spin texture by engineering geometrical boundary conditions in three-dimensional nanomagnets. By introducing a chirality interface between two three-dimensional double-helix nanowires of opposite handedness, forming a kinked, non-collinear structure, we impose competing topological constraints that uniquely define the magnetization configuration surrounding the Bloch point. A saturating magnetic field nucleates head-to-head or tail-to-tail domain configurations at the chirality interface, producing a Bloch-point domain wall with deterministic polarity, circulation and helicity. This geometrical approach enables full three-dimensional control of Bloch point domain walls allowing deterministic engineering of their spin texture and its selective coupling to current-induced Oersted fields.

Substrate-mediated CVT growth enables highly crystalline 3R-TaSe 2 nanocrystals exhibiting charge density wave behavior at ∼100 K and superconductivity below 2.2 K.

The design of van der Waals (vdW) heterostructures by integrating distinct two-dimensional (2D) materials remains a central strategy for tailoring novel functionalities or enhancing intrinsic properties beyond those of their individual components. In this work, direct epitaxial Bi2Te3/MoS2 vdW heterostructures are synthesized via a sequential chemical vapor transport (CVT) approach. By optimizing the growth parameters, it was observed that the deposition of Bi2Te3 crystals is highly substrate-dependent, with preferential nucleation occurring on MoS2 rather than directly on the sapphire substrate. This selective nucleation may be related to the different surface diffusion characteristics of MoS2 and sapphire. Compared with sapphire, the MoS2 surface provides more favorable diffusion and nucleation conditions for Bi-Te species, promoting preferential lateral growth of Bi2Te3 on MoS2. Furthermore, the lateral size and thickness of Bi2Te3 crystals vary over a broad range as a function of the growth conditions. These findings provide practical insights into parameter-controlled growth of Bi2Te3/MoS2 vdW heterostructures using sequential CVT and highlight their potential for applications in electronic and optoelectronic devices.

Intercalation of spin-bearing 3d transition metals into nonmagnetic transition metal dichalcogenides (TMDs) offers an effective route to induce and control magnetism in layered materials. However, progress has been hindered by the lack of scalable and controllable synthesis methods, which are mainly based on chemical vapor transport and subsequent mechanical exfoliation. Here, we utilize a scalable atmospheric pressure chemical vapor deposition (APCVD) approach to intercalate Cr into the van der Waals (vdW) gaps of 2H-NbS2. Energy-dispersive X-ray spectroscopy shows that the produced hexagonal crystals closely match the Cr1/3NbS2 stoichiometry, a chiral helimagnet of interest for spintronic applications. Transmission electron microscopy and Raman spectroscopy further verify the successful preparation of Cr1/3NbS2 with a dominantly ordered 3 & times; 3 Cr superlattice. Linear/circular polarized Raman measurements together with density functional theory calculations were utilized to assign vibrational mode symmetries in Cr1/3NbS2, serving as clear guidelines for future studies. Magneto-transport measurements revealed a strong dependence of the magnetic properties of Cr1/3NbS2 on the thickness. Interestingly, crystals thinner than the helix pitch deviate from the conventional in-plane helical structure, which gives rise to an out-of-plane magnetic component under an applied perpendicular magnetic field. This work introduces a scalable route for synthesizing magnetic intercalated TMDs and provides a platform for exploring the thickness-property relationships in low-dimensional chiral helimagnets.

Additive manufacturing technologies have proven to be an excellent alternative to conventional production methods, especially when geometrically complex parts and low production quantities are aimed at. Specifically, powder bed fusion of metals using a laser beam (PBF-LB/M) additionally allows for the manufacturing of mechanically highly stressable parts. However, the heat input through the laser beam into the material and an irregular cooling during the processing result in the formation of high residual stresses. These lead to form deviations outside the specified tolerances and may accumulate to an extent, at which stress-induced cracking occurs. This emphasizes the need for an accurate prediction of the residual stresses during the PBF-LB/M process with the goal of a first-time-right additive manufacturing. In this study, three specimens exhibiting high residual stress formations during PBF-LB/M were manufactured from the nickel-based superalloy Inconel 718. Afterwards, the stresses were measured by means of neutron diffraction. The results provided the validation data for a subsequent finite element simulation, representing the build-up process on a part-scale, in which the data evaluation was conducted in accordance with the measurements for a high comparability. A comparison between the simulation and the neutron diffraction results of all three specimens showed a very good agreement of the normal stresses in all three coordinate directions, both for tensile and compressive stresses. The obtained results highlight the validity of the applied simplified part-scale simulation. The latter can, therefore, be utilized to increase the process understanding of residual stress and crack formations. It can also be used to enable process parameter modifications or geometry adaptions, aiming at a first-time-right additive manufacturing.

We report a novel atomic layer deposition (ALD) process for SnO2 that does not require water or other strong oxidizing agents, such as H2O, O2 plasma, O3, or H2O2. The development of alternative oxidant-free ALD processes is highly attractive because it enables a gentler and more controllable chemical environment, which is crucial for next-generation nanoscale devices and complex material stacks. In this approach, Sn-based complementary metal precursors are employed: Sn(OtBu)4 serves as both the tin and oxygen precursor, while SnCl4 acts as an additional tin source. For this precursor combination, an optimal ALD temperature window of 70-90 °C was established, within which amorphous SnO2 films are deposited. Post-deposition annealing is subsequently required to develop the desired crystallinity and to adjust the oxygen-vacancy concentration and impurity levels, which ultimately determine the electrical and optical properties of the resulting SnO2 films and their potential for various applications. To gain mechanistic insight into this oxidant-free SnO2 growth process, we employ density functional theory (DFT) calculations to investigate the surface reactions during sequential exposure of Sn(OtBu)4 and SnCl4 on a SiO2 substrate. The results reveal key atomic-level processes, including ligand-exchange pathways, oxygen transfer, and surface regeneration, which govern film growth. This combined experimental and theoretical approach provides fundamental understanding of the SnO2 ALD mechanism and offers guidance for post-deposition optimization of the material.

Reproducibility in the synthesis of complex materials such as metal-organic frameworks (MOFs) remains a major challenge. Under seemingly identical experimental conditions, a distribution of MOF crystals with different structural properties is obtained, resulting in a heterogeneous performance. For quality assurance, analytical techniques and protocols are needed to predict MOF crystal quality already during the synthesis process. In this work, in situ Raman spectroscopy is used to monitor the formation of 2D phthalocyanine-based MOFs at the air-water interface. Raman marker bands are identified that visualise the competing processes of linker aggregation and MOF formation. Using transmission electron microscopy (TEM) measurements on the MOF crystals after synthesis, a correlation between the Raman marker bands and the resulting crystalline domain size distribution of the MOF can be derived. This noninvasive, fast, and simple in situ quality assessment method marks a significant step toward automated MOF synthesis.

Creation of chirality through screw dislocation-driven growth for highly crystalline nano-WSe 2 by chemical vapor transport based on thermodynamic simulations.

We measure the electron beam-induced current to analyze the electron-induced secondary electron (SE) emission from micron-sized gold particles illuminated by 80 and 300 keV electrons in a transmission electron microscope. A direct comparison of the experimental and simulated SE emission (SEE) employing Monte Carlo scattering simulations based on the GEANT4 toolkit yields overall good agreement with a noticeable discrepancy arising from the shortcoming of the GEANT4 scattering cross sections in the low-loss regime. Thus, the electron beam-induced current analysis allows to quantify the inelastic scattering including SEE in the transmission electron microscope and provides further insight into the charging mechanisms.

Niobium disulfide is a member of the metallic two-dimensional layered transition metal dichalcogenides (TMDs) family with a thermodynamically stable 3R-structure. Despite the difficulties involved in controlling the growth of NbS2 crystals with a well-defined structure, a rational approach of bottom-up synthesis of NbS2 nanostructures was performed to achieve this. The parameters of the synthesis by chemical vapor transport (CVT) were derived by thermodynamic simulations of the reaction pathway according to TRAGMIN. High-quality 3R NbS2 nanocrystals were successfully deposited directly on thermal-oxidized Si/SiO2 (100) and thermal-oxidized C-plane sapphire substrates. By using short time vapor transport (0.5 h) and addition of iodine in the temperature range between 600 and 800 degrees C, a thickness down to 7 nm (similar to 12 layers) was achieved. The high-crystallinity morphology of the deposited nanocrystals was confirmed by high-resolution transmission electron microscopy, selected area electron diffraction, and atomic force microscopy as well as double-polarized Raman spectroscopy. Our work explores an important synthesis route to obtain a well-determined phase structure, which is a crucial factor to be considered if practical applications should be realized in the future.