Engineering light-matter interactions between multiple free-space quantum emitters is a central challenge for scalable quantum photonic technologies. In particular, accessing regimes of coherent emitter-emitter interactions, where several emitters are coupled through a shared electromagnetic environment, is essential for coherent emission and quantum functionalities. Such interactions require precise control over emitter separation and stabilization at sub-wavelength distances, a level of spatial organization that remains extremely difficult to achieve at the molecular scale in solid-state systems. Here we introduce Encoded Quantum Chains (EQC), a one-dimensional architecture in which cooperative radiative behaviour is programmed through spatial encoding of identical molecular emitters. Organic emitters and inert spacer molecules are co-encapsulated inside dielectric boron nitride nanotubes (BNNTs), enabling statistical control of intermolecular spacing from nanometres to micrometres while enforcing dipole alignment and one-dimensional confinement. Time-resolved fluorescence under ambient conditions reveals accelerated radiative decay, enhanced emission rates per emitter, and the emergence of non-mono-exponential dynamics as spacing falls below the optical wavelength, consistent with cooperative radiative states in one dimension. Bundling of EQCs enables coupling between emitters in neighbouring BNNTs, driving a dimensional crossover toward higher-dimensional delocalisation of the excitation. This modular building-block approach provides a scalable route to engineer light-matter interactions and many-body optical phenomena in confined molecular systems, opening new opportunities for distributed single-photon sources, programmable quantum emitters, and photonic architectures for quantum technologies.

The effect of pre-oxidation at 600 degrees C for 3000 h on the fatigue behavior of a forged bimodal Ti6242S alloy was investigated through fatigue lifetime analysis. An embrittlement stress threshold was identified, beyond which fatigue life is significantly reduced at both room temperature (RT) and 550 degrees C, with threshold stresses of 645 MPa and 450 MPa, respectively. Below this threshold at RT, pre-oxidation does not influence fatigue life, whereas at high temperatures, lifetimes are systematically reduced by at least an order of magnitude compared to non-oxidized references. The formation of a 100 mu m oxygen-rich layer (ORL) modifies crack front geometry from elliptic to crescent-shaped and alters crack initiation mechanisms, leading to faceted crack initiation around the specimen diameter and within the ORL. Fractographic analysis shows that propagation follows a two-stage process, with short faceted crack growth occurring within the ORL before transitioning to long crack propagation with striations. Despite these changes, pre-oxidation does not affect the long crack growth rate or the stress intensity factor at fracture. The embrittlement stress threshold is therefore discussed in relation to the accelerated propagation of short faceted cracks in the ORL. TEM observations further suggest that the reduction in fatigue life may be linked to a shift in crack initiation mechanisms and increased short crack growth rate within the ORL.

The crystallographic orientation of anisotropic 2D materials plays a crucial role in their physical properties and device performance. However, standard orientation techniques such as transmission electron microscopy (TEM) or X‐ray diffraction can be complex and less accessible for routine characterization. Herein, the orientation of black phosphorus (BP) from bulk crystals to thin layers is investigated using angle‐resolved polarized Raman spectroscopy with a single‐wavelength (514 nm) Raman setup. By incorporating thickness‐dependent interference effects and anisotropic optical indices, this approach provides a reliable framework for orientation determination across different BP thicknesses. The method is validated through direct orientation measurements using TEM and electron backscattering diffraction, confirming its applicability to both thick and ultrathin samples. Given its simplicity and compatibility with widely available Raman setups, this approach offers a practical solution for characterizing BP orientation without requiring advanced structural characterization techniques.

Precise Fe concentration measurements are essential to understand the kinetics of precipitation and evolution of mechanical properties in Al-Fe alloys. Moreover, with the increasing proportion of recycled metals, it is mandatory to rely on techniques capable of tracking impurities in Al-alloys to elucidate their effects on microstructure and properties. Atom Probe Tomography (APT) is a powerful material analysis tool capable of precise composition measurements. As it relies on time-of-flight mass spectrometry, the quality of the composition measurements is highly dependent on the proper peak identification and solving peak overlapping. The complexity of peak decomposition multiplies if molecular ions such as hydrides or oxides are present in the mass spectrum. Al-Fe is one of these systems, where three out of four peaks of Fe isotopes are overlapping with Al, AlH, and AlH2 mass intervals. To solve this complex peak overlapping case, an approach has been developed here. It is based on acquiring the Al-hydride formation ratio from APT analyses of standard materials, where no overlap with Fe peaks is observed. This simple method aims to improve the precision of Fe concentration measurements in Al-Fe system.

While high operating temperature infrared photodetection remains a major technological objective, huge improvements have been obtained through the use of increasingly complex semiconductors epitaxies such as quantum cascade structures or III–V superlattice junction. However, the characterization of these layers is challenging and often requires the use of destructive processes. Here, SNOM imaging and spectroscopy on a mechanically cleaved facet is used to characterize the different layers of a complex epitaxial heterostructure composed of a type II superlattice and highly doped semiconductors. These near‐field experimental data are compared to simulation in order to retrieve both the cut‐off frequency of the superlattice and the doping level of each highly doped semiconductor layers. Additionally, information about interfaces is optically retrieved through hyperspectral characterization of plasmons propagating at these vertical interfaces. In parallel, all the materials and exact stacking of the epitaxy are confirmed through scanning transmission electron microscopy.

Discovering an efficient spintronic semiconductor workhorse with dual host capabilities as a channel and spin valve barrier remains one of the most elusive endeavors toward the development of spin-logic circuits. Graphene paved the way for two-dimensional (2D) materials, yet engineering a controlled band gap in it remains a challenge. Black phosphorus (BP) was recently unveiled as a potential candidate in the realm of 2D semiconductors, with carrier mobilities among the largest reported for a 2D material and a low spin-orbit coupling reminiscent of graphene. Although promising spin transport properties have already been reported, their potential for tunneling and spin injection remains uncharted. Here, we unveil an unknown spin transport mechanism spin-split in k-space and report on corresponding high magnetoresistance spin signals up to 500% in BP based spin valves. Those findings are analyzed and discussed in light of a first-principles theoretical investigation showing BP's potential for spin filtering beyond its expected role of spin transport channel. This strongly supports BP's vision as an outstanding platform for spintronics, as it could become a versatile workhorse yet unavailable with any other semiconductor.

Perovskite nanocrystals have attracted much attention in the last ten years due to their different applications, especially in the photovoltaic domain and LED performance. In this large family of perovskite nanocrystals, CsPbBr3 nanocrystals are attractive nanomaterials because they are good candidates for obtaining green emissions and exploring new synthesis routes. In this context, controlling the nanometric scale's morphology, particularly the size and monodispersity, is fundamental for exploring their photophysical properties and final applications. Currently, the nanometric size of nanocrystals is ensured by the presence of oleic acid and oleylamine molecules, in using Hot Injection (HI) or ligand-assisted reprecipitation (LARP) methods. If oleic acid plays a fundamental role, oleylamine can be easily substituted by other amino molecules, opening the way for the functionalization of CsPbBr3 nanocrystals and the obtention of new hybrid perovskite nanocrystal families. In this article, we describe the synthesis, by soft chemistry, of a new family of hybrid organic-inorganic CsPbBr3 nanocrystals, functionalized by aryl-alkylamine (AAA) molecules, through the modified LARP method. We highlight the mechanism for cutting submicron crystals into nanocrystals, using aryl-alkylamine molecules like scissors. The impact of these amino molecules on the final nanocrystals leads to different nanocrystal morphologies (nanocubes, nanosheets, or nanorods) and structures (monoclinic, rhombohedral, or tetragonal). In addition, this modified LARP method highlights, under certain experimental conditions, an unexpected formation of PbO ribbons.

Hexagonal boron nitride encapsulation is the method of choice for protecting graphene from environmental doping and impurity scattering. It was previously demonstrated that metal-organic vapor phase epitaxy (MOVPE) grows epitaxially ordered, uniform BN layers on epigraphene (graphene grown on SiC). Due to graphene's nonwetting properties, h-BN growth starts preferentially from the graphene ledges. We use this fact here to selectively promote the growth of high-quality flat h-BN on epigraphene by patterning epigraphene microstructures prior to BN growth. Thin h-BN films (down to 6 nm) grown by MOVPE show a smooth and pleated surface morphology on epigraphene, whereas crumpled BN is observed on the SiC. Cross-sectional high-resolution transmission electron microscopy images and fluorescence imaging confirm the higher BN quality grown on the epigraphene. Transport measurements reveal p-doping, as expected from hydrogen intercalation of epigraphene and regions of high and low mobility. This method can be used to produce structurally uniform high-quality h-BN/epigraphene micro/nanoscale heterostructures.

Here, we report on the low-pressure chemical vapor deposition synthesis of multilayer BN films on single crystalline Ni(111) films. We highlight the crucial role of substrate pretreatment to stabilize the Ni(111) thin film on YSZ/Si(111) prior to BN precursor exposure at high temperature. We show that an in situ double-step thermal process under primary vacuum allows us to obtain clean and flat nickel surfaces suitable for homogeneous BN growth. Scanning and transmission electron microscopies, Raman spectroscopy, and atomic force microscopy have been used to characterize statistically the BN film from the atomic to the millimeter scale. We show that we obtain a sp2-hybridized BN film with a rhombohedral ABC stacking sequence. The 3 nm-thick film is continuous at the millimeter scale, with a mean roughness of 0.9 nm and no wrinkles.

Recent advancements in materials science have shed light on the potential of exploring hierarchical assemblies of molecules on surfaces, driven by both fundamental and applicative challenges. This field encompasses diverse areas including molecular storage, drug delivery, catalysis, and nanoscale chemical reactions. In this context, the utilization of nanotube templates (NTs) has emerged as promising platforms for achieving advanced one-dimensional (1D) molecular assemblies. NTs offer cylindrical, crystalline structures with high aspect ratios, capable of hosting molecules both externally and internally (Mol@NT). Furthermore, NTs possess a wide array of available diameters, providing tunability for tailored assembly. This review underscores recent breakthroughs in the field of Mol@NT. The first part focuses on the diverse panorama of structural properties in Mol@NT synthesized in the last decade. The advances in understanding encapsulation, adsorption, and ordering mechanisms are detailed. In a second part, the review highlights the physical interactions and photophysics properties of Mol@NT obtained by the confinement of molecules and nanotubes in the van der Waals distance regime. The last part of the review describes potential applicative fields of these 1D heterostructures, providing specific examples in photovoltaics, luminescent materials, and bio-imaging. A conclusion gathers current challenges and perspectives of the field to foster discussion in related communities.

Black phosphorus (BP) stands out from other two-dimensional (2D) materials by the wide amplitude of the band-gap energy (Eg) that sweeps an optical window from visible to infrared wavelengths, depending on the layer thickness. This singularity made optical and excitonic properties of BP difficult to map. Here we report a comprehensive study of the intrinsic (i.e., measured at 4 K) optical properties of 79 passivated BP flakes obtained by mechanical exfoliation of thickness ranging from 4 to 700 nm. By following single- or multistamp exfoliation protocols and by combining micro-Raman and photoluminescence experiments, we demonstrate that the exfoliation step induces line like defects which open radiative recombination paths alternative to those of the crystalline bulk and that actually dominate the emission process. We also show that the evolution of the photoluminescence energy versus thickness follows an inverse square law. We relate this to a quantum well model whose validity is discussed and justified at intermediate thickness. Finally, we report that the emission energy of BP slabs placed in different 2D heterostructures is not significantly modulated by the dielectric environment.

Despite its simple crystal structure, layered boron nitride features a surprisingly complex variety of phonon-assisted luminescence peaks. We present a combined experimental and theoretical study on ultraviolet-light emission in hexagonal and rhombohedral bulk boron nitride crystals. Emission spectra of high-quality samples are measured via cathodoluminescence spectroscopy, displaying characteristic differences between the two polytypes. These differences are explained using a fully first-principles computational technique that takes into account radiative emission from “indirect”, finite-momentum, excitons via coupling to finite-momentum phonons. We show that the differences in peak positions, number of peaks and relative intensities can be qualitatively and quantitatively explained, once a full integration over all relevant momenta of excitons and phonons is performed.

Polarized fluorescence emission of nanoscale emitters has been extensively studied for applications such as bioimaging, displays, and optical communication. Extending the polarization properties in large assemblies of compact emitters is, however, challenging because of self-aggregation processes, which can induce depolarization effects, quenching, and cancellations of molecular dipoles. Here we use α-sexithiophene (6T) molecules confined inside boron nitride nanotubes (6T@BNNTs) to induce fluorescence anisotropy in a transparent host. The experiments first indicate that individual 6T@BNNTs exhibit a high polarization extinction ratio, up to 700, at room temperature. Using aberration-corrected HRTEM, we show that the fluorescence anisotropy is consistent with a general alignment of encapsulated 6T molecules along the nanotube axis. The molecular alignment is weakly influenced by the nanotube diameter, a phenomenon ascribed to stronger molecule-to-sidewall interactions compared to intermolecular interactions. By stretching a flexible thin film made of transparent polymers mixed with 6T@BNNTs, we induce a macroscopic fluorescence anisotropy within the film. This work demonstrates that the dyes@BNNT system can be used as an easy-to-handle platform to induce fluorescence anisotropy in photonic materials.

Passivating graphene with a layer of hexagonal boron nitride (hBN) is known to protect it from environment effects that degrade its mobility. However, growth of high-quality BN on graphene is challenging because of the lack of surface dangling bonds. Here, we report the growth of thin BN films (down to 10 nm) on monolayer epigraphene grown on silicon carbide single-crystal substrates using metal-organic vapor phase epitaxy (MOVPE). The BN film has continuous coverage on the epigraphene surface, with smooth morphology. Particles consisting of layered BN are also observed on the surface with a higher density at the step edges. High-Resolution Scanning Transmission Electron Microscopy (HRSTEM) reveals high structural quality BN layers, with a clean and abrupt interface with graphene. The BN/epigraphene/SiC heterostructure is stable up to high temperature (1550 degrees C), and annealing improves its crystallinity. These results show that MOVPE growth technique has a potential for large-scale production of BN fully coated graphene and high-temperature applications.