Unveiling Composition-Properties Relationships in Mo1-xWxSe2 Alloys: A Theoretical and Experimental Study.

Two-dimensional transition metal dichalcogenide (TMD) alloys have emerged as a versatile platform for electronic, optoelectronic, and quantum applications due to their tunable crystal structure and unique electronic properties. In this study, we investigate the influence of atomic composition on the structural, electronic, and optical properties of the Mo1-xWxSe2 alloy, combining experimental and theoretical approaches. Samples with different Mo and W ratios were synthesized and characterized using Raman and photoluminescence (PL) spectroscopies, and atomic force microscopy (AFM).

Interplay of Energy and Charge Transfer in WSe/CrSBr Heterostructures.

van der Waals heterostructures (vdWHs) composed of transition-metal dichalcogenides (TMDs) and layered magnetic semiconductors offer great opportunities to manipulate the exciton and valley properties of TMDs. Here, we present magneto-photoluminescence (PL) studies in a WSe monolayer (ML) on a CrSBr crystal, an anisotropic layered antiferromagnetic semiconductor. Our results reveal the unique behavior of each of the ML-WSe PL peaks under a magnetic field that is distinct from the pristine case.

Correction: Nanophotonics of mid-infrared plasmon-polaritons at interfaces between metals and two-dimensional crystals.

Correction for 'Nanophotonics of mid-infrared plasmon-polaritons at interfaces between metals and two-dimensional crystals' by Flávio H. Feres, , , 2025, , 13229-13237, https://doi.org/10.

Nanophotonics of mid-infrared plasmon-polaritons at interfaces between metals and two-dimensional crystals.

The optical response of metal/dielectric interfaces is largely influenced by surface plasmon-polariton (SPP) modes. In the mid-infrared (IR) range, SPPs can probe the inner physicochemical properties of metal/dielectric systems, including interfaces with mid-IR polaritonic 2D crystals. Using advanced nanoscopy techniques, we characterize mid-IR SPP modes at air/gold and hexagonal boron nitride (hBN) 2D crystal/gold interfaces synchrotron infrared nanospectroscopy (SINS) and scattering-scanning near-field optical microscopy (s-SNOM) imaging.

Ultra-confined plasmons reveal moiré patterns in a twisted bilayer graphene-talc heterostructure.

This work investigates the plasmonic properties of a twisted bilayer graphene (TBG) and talc heterostructure. Talc, a naturally occurring phyllosilicate, promotes p-type charging of graphene, supporting high charge mobility and strong interaction between graphene plasmons and talc's phonon polaritons. This interaction results in the formation of surface plasmon-phonon polariton (SP) modes, which are detected using infrared scattering-type scanning near-field optical microscopy (IR s-SNOM) at room temperature.

Optical Memory in a MoSe/Clinochlore Device.

Two-dimensional heterostructures have been crucial in advancing optoelectronic devices utilizing van der Waals materials. Semiconducting transition-metal dichalcogenide monolayers, known for their unique optical properties, offer extensive possibilities for light-emitting devices. Recently, a memory-driven optical device, termed a Mem-emitter, was proposed by using these monolayers atop dielectric substrates.

The Emergence of Mem-Emitters.

The advent of memristors and resistive switching has transformed solid-state physics, enabling advanced applications such as neuromorphic computing. Inspired by these developments, we introduce the concept of Mem-emitters, devices that manipulate light-emission properties of semiconductors to achieve memory functionalities. Mem-emitters, influenced by past exposure to stimuli, offer a new approach to optoelectronic computing with potential for enhanced speed, efficiency, and integration.

Investigating the impact of ITO substrates on the optical and electronic properties of WSemonolayers.

Two-dimensional (2D) materials, particularly transition metal dichalcogenides (TMDs), have gathered significant attention due to their interesting electrical and optical properties. Among TMDs, monolayers of WSeexhibit a direct band gap and high exciton binding energy, which enhances photon emission and absorption even at room temperature. This study investigates the electronic and optical properties of WSemonolayers when they are mechanically transferred to indium tin oxide (ITO) substrates.

Ultrathin natural biotite crystals as a dielectric layer for van der Waals heterostructure applications.

Biotite, an iron-rich mineral belonging to the trioctahedral mica group, is a naturally abundant layered material (LM) exhibiting attractive electronic properties for application in nanodevices. Biotite stands out as a non-degradable LM under ambient conditions, featuring high-quality basal cleavage-a significant advantage for van der Waals heterostructure (vdWH) applications. In this work, we present the micro-mechanical exfoliation of biotite down to monolayers (1Ls), yielding ultrathin flakes with large areas and atomically flat surfaces.

Cutting-edge collagen biocomposite reinforced with 2D nano-talc for bone tissue engineering.

The advancement of nanobiocomposites reinforced with 2D nano-materials plays a pivotal role in enhancing bone tissue engineering. In this study, we introduce a nanobiocomposite that reinforces bovine collagen with 2D nano-talc, a recently exfoliated nano-mineral. These nanobiocomposites were prepared by blending collagen with varying concentrations of 2D nano-talc, encompassing mono- and few-layers talc from soapstone nanomaterial.

Impacts of dielectric screening on the luminescence of monolayer WSe.

Single layers of transition metal dichalcogenides (TMDCs), such as WSehave gathered increasing attention due to their intense electron-hole interactions, being considered promising candidates for developing novel optical applications. Within the few-layer regime, these systems become highly sensitive to the surrounding environment, enabling the possibility of using a proper substrate to tune desired aspects of these atomically-thin semiconductors. In this scenario, the dielectric environment provided by the substrates exerts significant influence on electronic and optical properties of these layered materials, affecting the electronic band-gap and the exciton binding energy.

Synthesis, Thermal Analysis, Spectroscopic Properties, and Degradation Process of Tutton Salts Doped with AgNO or HBO.

In this work, we synthesized and studied the spectroscopic properties of (NH)(SO)Y(HO) (Y = Ni, Mg) crystals doped with AgNO or HBO. These crystals constitute a series of hexahydrated salts known as Tutton salts. We investigated the influence of dopants on the vibrational modes of the tetrahedral ligands NH and SO, octahedral complexes Mg(HO) and Ni(HO), and HO molecules present in these crystals through Raman and infrared spectroscopies.

Review on infrared nanospectroscopy of natural 2D phyllosilicates.

Phyllosilicates have emerged as a promising class of large bandgap lamellar insulators. Their applications have been explored from the fabrication of graphene-based devices to 2D heterostructures based on transition metal dichalcogenides with enhanced optical and polaritonics properties. In this review, we provide an overview of the use of infrared (IR) scattering-type scanning near-field optical microscopy (s-SNOM) for studying nano-optics and local chemistry of a variety of 2D natural phyllosilicates.

Distinctive -Factor of Moiré-Confined Excitons in van der Waals Heterostructures.

We investigated the valley Zeeman splitting of excitonic peaks in the microphotoluminescence (μPL) spectra of high-quality hBN/WS/MoSe/hBN heterostructures under perpendicular magnetic fields up to 20 T. We identify two neutral exciton peaks in the μPL spectra; the lower-energy peak exhibits a reduced -factor relative to that of the higher energy peak and much lower than the recently reported values for interlayer excitons in other van der Waals (vdW) heterostructures. We provide evidence that such a discernible -factor stems from the spatial confinement of the exciton in the potential landscape created by the moiré pattern due to lattice mismatch or interlayer twist in heterobilayers.

Design and implementation of a device based on an off-axis parabolic mirror to perform luminescence experiments in a scanning tunneling microscope.

We present the design, implementation, and illustrative results of a light collection/injection strategy based on an off-axis parabolic mirror collector for a low-temperature Scanning Tunneling Microscope (STM). This device allows us to perform STM induced Light Emission (STM-LE) and Cathodoluminescence (STM-CL) experiments and in situ Photoluminescence (PL) and Raman spectroscopy as complementary techniques. Considering the Étendue conservation and using an off-axis parabolic mirror, it is possible to design a light collection and injection system that displays 72% of collection efficiency (considering the hemisphere above the sample surface) while maintaining high spectral resolution and minimizing signal loss.

Electrical and optical properties of transition metal dichalcogenides on talc dielectrics.

Advanced van der Waals (vdW) heterostructure devices rely on the incorporation of high quality dielectric materials which need to possess a low defect density as well as being atomically smooth and uniform. In this work we explore the use of talc dielectrics as a potentially clean alternative substrate to hexagonal boron nitride (hBN) for few-layer transition metal dichalcogenide (TMDC) transistors and excitonic TMDC monolayers. We find that talc dielectric transistors show small hysteresis which does not depend strongly on sweep rate and show negligible leakage current for our studied dielectric thicknesses.

Sub-diffractional cavity modes of terahertz hyperbolic phonon polaritons in tin oxide.

Hyperbolic phonon polaritons have recently attracted considerable attention in nanophotonics mostly due to their intrinsic strong electromagnetic field confinement, ultraslow polariton group velocities, and long lifetimes. Here we introduce tin oxide (SnO) nanobelts as a photonic platform for the transport of surface and volume phonon polaritons in the mid- to far-infrared frequency range. This report brings a comprehensive description of the polaritonic properties of SnO as a nanometer-sized dielectric and also as an engineered material in the form of a waveguide.

Tunneling-current-induced local excitonic luminescence in p-doped WSe monolayers.

We have studied the excitonic properties of exfoliated tungsten diselenide (WSe2) monolayers transferred to gold substrates using the tunneling current in a Scanning Tunneling Microscope (STM) operated in air to excite the light emission locally. In obtained spectra, emission energies are independent of the applied bias voltage and resemble photoluminescence (PL) results, indicating that, in both cases, the light emission is due to neutral and charged exciton recombination. Interestingly, the electron injection rate, that is, the tunneling current, can be used to control the ratio of charged to neutral exciton emission.

Dipole modelling for a robust description of subdiffractional polariton waves.

The nanophotonics of van der Waals (vdW) materials relies critically on the electromagnetic properties of polaritons defined on sub-diffraction length scales. Here, we use a full electromagnetic Hertzian dipole antenna (HDA) model to describe the hyperbolic phonon polaritons (HPs) in vdW crystals of hexagonal boron nitride (hBN) on a gold surface. The HP waves are investigated by broadband synchrotron infrared nanospectroscopy (SINS) which covers the type I and type II hyperbolic bands simultaneously.

Synchrotron infrared nanospectroscopy on a graphene chip.

A recurring goal in biology and biomedicine research is to access the biochemistry of biological processes in liquids that represent the environmental conditions of living organisms. These demands are becoming even more specific as microscopy techniques are fast evolving in the era of single cell analysis. In the modality of chemical probes, synchrotron infrared spectroscopy (μ-FTIR) is a technique that is extremely sensitive to vibrational responses of materials; however, the classical optical limits prevent the technique to access the biochemistry of specimens at the subcellular level.

Exfoliation and characterization of a two-dimensional serpentine-based material.

We report on an experimental investigation of serpentine, an abundant phyllosilicate, as an alternative source of two-dimensional (2D) nanomaterials. We show, through scanning probe microscopy (SPM) measurements, that natural serpentine mineral can be mechanically exfoliated down to few-layer flakes, where monolayers can be easily resolved. The parent serpentine bulk material was initially characterized via conventional techniques like XRD, XPS, FTIR and Raman spectroscopies and the results show that it is predominantly constituted by the antigorite mineral.

Anisotropic Flow Control and Gate Modulation of Hybrid Phonon-Polaritons.

Light-matter interaction in two-dimensional photonic or phononic materials allows for the confinement and manipulation of free-space radiation at sub-wavelength scales. Most notably, the van der Waals heterostructure composed of graphene (G) and hexagonal boron nitride (hBN) provides for gate-tunable hybrid hyperbolic plasmon phonon-polaritons (HP). Here, we present the anisotropic flow control and gate-voltage modulation of HP modes in G-hBN on an air-Au microstructured substrate.

Graphene/h-BN plasmon-phonon coupling and plasmon delocalization observed by infrared nano-spectroscopy.

We observed the coupling of graphene Dirac plasmons with different surfaces using scattering-type scanning near-field optical microscopy integrated into a mid-infrared synchrotron-based beamline. A systematic investigation of a graphene/hexagonal boron nitride (h-BN) heterostructure is carried out and compared with the well-known graphene/SiO2 heterostructure. Broadband infrared scanning near-field optical microscopy imaging is able to distinguish between the graphene/h-BN and the graphene/SiO2 heterostructure as well as differentiate between graphene stacks with different numbers of layers.