Mapping of Vibrational Modes Revealing a Strong and Tunable Coupling in Two Juxtaposed 3R-WSe Nanodrums.

Two-dimensional (2D) material resonators have emerged as promising platforms for advanced nanomechanical applications due to their exceptional mechanical properties, tunability, and nonlinearities. We explored the strong mechanical mode coupling between two adjacent 3R-WSe nanodrums at room temperature. Combining a piezoelectric material, as noncentrosymmetric 3R-WSe, and vibration manipulation is the building block for phononic experiments with 2D materials.

Atomic-Layer Controlled Transition from Inverse Rashba-Edelstein Effect to Inverse Spin Hall Effect in 2D PtSe Probed by THz Spintronic Emission.

2D materials, such as transition metal dichalcogenides, are ideal platforms for spin-to-charge conversion (SCC) as they possess strong spin-orbit coupling (SOC), reduced dimensionality and crystal symmetries as well as tuneable band structure, compared to metallic structures. Moreover, SCC can be tuned with the number of layers, electric field, or strain. Here, SCC in epitaxially grown 2D PtSe by THz spintronic emission is studied since its 1T crystal symmetry and strong SOC favor SCC.

Reconfigurable Multifunctional van der Waals Ferroelectric Devices and Logic Circuits.

Emerging reconfigurable devices are fast gaining popularity in the search for next-generation computing hardware, while ferroelectric engineering of the doping state in semiconductor materials has the potential to offer alternatives to traditional von-Neumann architecture. In this work, we combine these concepts and demonstrate the suitability of reconfigurable ferroelectric field-effect transistors (Re-FeFETs) for designing nonvolatile reconfigurable logic-in-memory circuits with multifunctional capabilities. Modulation of the energy landscape within a homojunction of a 2D tungsten diselenide (WSe) layer is achieved by independently controlling two split-gate electrodes made of a ferroelectric 2D copper indium thiophosphate (CuInPS) layer.

Quasi van der Waals Epitaxy of Rhombohedral-Stacked Bilayer WSe on GaP(111) Heterostructure.

The growth of bilayers of two-dimensional (2D) materials on conventional 3D semiconductors results in 2D/3D hybrid heterostructures, which can provide additional advantages over more established 3D semiconductors while retaining some specificities of 2D materials. Understanding and exploiting these phenomena hinge on knowing the electronic properties and the hybridization of these structures. Here, we demonstrate that a rhombohedral-stacked bilayer (AB stacking) can be obtained by molecular beam epitaxy growth of tungsten diselenide (WSe) on a gallium phosphide (GaP) substrate.

Quantum Confinement and Electronic Structure at the Surface of van der Waals Ferroelectric -InSe.

Two-dimensional (2D) ferroelectric (FE) materials are promising compounds for next-generation nonvolatile memories due to their low energy consumption and high endurance. Among them, α-InSe has drawn particular attention due to its in- and out-of-plane ferroelectricity, whose robustness has been demonstrated down to the monolayer limit. This is a relatively uncommon behavior since most bulk FE materials lose their ferroelectric character at the 2D limit due to the depolarization field.

High p doped and robust band structure in Mg-doped hexagonal boron nitride.

In two dimensional materials, substitutional doping during growth can be used to alter the electronic properties. Here, we report on the stable growth of p-type hexagonal boron nitride (h-BN) using Mg-atoms as substitutional impurities in the h-BN honeycomb lattice. We use micro-Raman spectroscopy, angle-resolved photoemission measurements (nano-ARPES) and Kelvin probe force microscopy (KPFM) to study the electronic properties of Mg-doped h-BN grown by solidification from a ternary Mg-B-N system.

Metal-insulator crossover in monolayer MoS.

We report on transport measurements in monolayer MoSdevices, close to the bottom of the conduction band edge. These devices were annealedbefore electrical measurements. This allows us to obtain good ohmic contacts at low temperatures, and to measure precisely the conductivity and mobility via four-probe measurements.

Photoferroelectric All-van-der-Waals Heterostructure for Multimode Neuromorphic Ferroelectric Transistors.

Interface-driven effects in ferroelectric van der Waals (vdW) heterostructures provide fresh opportunities in the search for alternative device architectures toward overcoming the von Neumann bottleneck. However, their implementation is still in its infancy, mostly by electrical control. It is of utmost interest to develop strategies for additional optical and multistate control in the quest for novel neuromorphic architectures.

Visualizing Giant Ferroelectric Gating Effects in Large-Scale WSe/BiFeO Heterostructures.

Multilayers based on quantum materials (complex oxides, topological insulators, transition-metal dichalcogenides, etc.) have enabled the design of devices that could revolutionize microelectronics and optoelectronics. However, heterostructures incorporating quantum materials from different families remain scarce, while they would immensely broaden the range of possible applications.

Unidirectional Rashba spin splitting in single layer WSSealloy.

Atomically thin two-dimensional (2D) layered semiconductors such as transition metal dichalcogenides have attracted considerable attention due to their tunable band gap, intriguing spin-valley physics, piezoelectric effects and potential device applications. Here we study the electronic properties of a single layer WSSealloys. The electronic structure of this alloy, explored using angle resolved photoemission spectroscopy, shows a clear valence band structure anisotropy characterized by two paraboloids shifted in one direction of the-space by a constant in-plane vector.

Hybridization and localized flat band in the WSe/MoSeheterobilayer.

Nearly localized moiré flat bands in momentum space, arising at particular twist angles, are the key to achieve correlated effects in transition-metal dichalcogenides. Here, we use angle-resolved photoemission spectroscopy (ARPES) to visualize the presence of a flat band near the Fermi level of van der Waals WSe/MoSeheterobilayer grown by molecular beam epitaxy. This flat band is localized near the Fermi level and has a width of several hundred meVs.

Vanishing Confinement Regime in Terahertz HgTe Nanocrystals Studied under Extreme Conditions of Temperature and Pressure.

While HgTe nanocrystals (NCs) in the mid-infrared region have reached a high level of maturity, their far-infrared counterparts remain far less studied, raising the need for an in-depth investigation of the material before efficient device integration can be considered. Here, we explore the effect of temperature and pressure on the structural, spectroscopic, and transport properties of HgTe NCs displaying an intraband absorption at 10 THz. The temperature leads to a very weak modulation of the spectrum as opposed to what was observed for strongly confined HgTe NCs.

Evidence for highly p-type doping and type II band alignment in large scale monolayer WSe/Se-terminated GaAs heterojunction grown by molecular beam epitaxy.

Two-dimensional materials (2D) arranged in hybrid van der Waals (vdW) heterostructures provide a route toward the assembly of 2D and conventional III-V semiconductors. Here, we report the structural and electronic properties of single layer WSe grown by molecular beam epitaxy on Se-terminated GaAs(111)B. Reflection high-energy electron diffraction images exhibit sharp streaky features indicative of a high-quality WSe layer produced vdW epitaxy.

Strain and Spin-Orbit Coupling Engineering in Twisted WS/Graphene Heterobilayer.

The strain in hybrid van der Waals heterostructures, made of two distinct two-dimensional van der Waals materials, offers an interesting handle on their corresponding electronic band structure. Such strain can be engineered by changing the relative crystallographic orientation between the constitutive monolayers, notably, the angular misorientation, also known as the "twist angle". By combining angle-resolved photoemission spectroscopy with density functional theory calculations, we investigate here the band structure of the WS/graphene heterobilayer for various twist angles.

Flat Bands and Giant Light-Matter Interaction in Hexagonal Boron Nitride.

Dispersionless energy bands in k space are a peculiar property gathering increasing attention for the emergence of novel electronic, magnetic, and photonic properties. Here, we explore the impact of electronic flat bands on the light-matter interaction. The van der Waals interaction between the atomic layers of hexagonal boron nitride induces flat bands along specific lines of the Brillouin zone.

A review of the classification systems for marine benthic habitats and the new updated Barcelona Convention classification for the Mediterranean.

The Mediterranean Sea supports high levels of biodiversity and complexity but is facing increasing human pressures, so that strategies to protect and recover its ecosystems must be a priority in environmental policies. Benthic cartography represents the first step of marine spatial planning for the proper management and protection of our sea. Univocal habitat classification systems are thus needed to map, monitor, and inventory marine habitats, and to guarantee common and shared frames for a harmonized interpretation of the Mediterranean habitat types.

Phase Transition in a Memristive Suspended MoS Monolayer Probed by Opto- and Electro-Mechanics.

Semiconducting monolayers of a 2D material are able to concatenate multiple interesting properties into a single component. Here, by combining opto-mechanical and electronic measurements, we demonstrate the presence of a partial 2H-1T' phase transition in a suspended 2D monolayer membrane of MoS. Electronic transport shows unexpected memristive properties in the MoS membrane, in the absence of any external dopants.

Reconfigurable 2D/0D p-n Graphene/HgTe Nanocrystal Heterostructure for Infrared Detection.

Nanocrystals are promising building blocks for the development of low-cost infrared optoelectronics. Gating a nanocrystal film in a phototransistor geometry is commonly proposed as a strategy to tune the signal-to-noise ratio by carefully controlling the carrier density within the semiconductor. However, the performance improvement has so far been quite marginal.

Electronic heat flow and thermal shot noise in quantum circuits.

When assembling individual quantum components into a mesoscopic circuit, the interplay between Coulomb interaction and charge granularity breaks down the classical laws of electrical impedance composition. Here we explore experimentally the thermal consequences, and observe an additional quantum mechanism of electronic heat transport. The investigated, broadly tunable test-bed circuit is composed of a micron-scale metallic node connected to one electronic channel and a resistance.

Field-Effect Transistor and Photo-Transistor of Narrow-Band-Gap Nanocrystal Arrays Using Ionic Glasses.

The gating of nanocrystal films is currently driven by two approaches: either the use of a dielectric such as SiO or the use of electrolyte. SiO allows fast bias sweeping over a broad range of temperatures but requires a large operating bias. Electrolytes, thanks to large capacitances, lead to the significant reduction of operating bias but are limited to slow and quasi-room-temperature operation.

Wave-Function Engineering in HgSe/HgTe Colloidal Heterostructures To Enhance Mid-infrared Photoconductive Properties.

The use of intraband transition is an interesting alternative path for the design of optically active complex colloidal materials in the mid-infrared range. However, so far, the performance obtained for photodetection based on intraband transition remains much smaller than the one relying on interband transition in narrow-band-gap materials operating at the same wavelength. New strategies have to be developed to make intraband materials more effective.

Tunable quantum criticality and super-ballistic transport in a "charge" Kondo circuit.

Quantum phase transitions (QPTs) are ubiquitous in strongly correlated materials. However, the microscopic complexity of these systems impedes the quantitative understanding of QPTs. We observed and thoroughly analyzed the rich strongly correlated physics in two profoundly dissimilar regimes of quantum criticality.

Intrinsic Properties of Suspended MoS on SiO/Si Pillar Arrays for Nanomechanics and Optics.

Semiconducting two-dimensional (2D) materials, such as transition-metal dichalcogenides (TMDs), are emerging in nanomechanics, optoelectronics, and thermal transport. In each of these fields, perfect control over 2D material properties including strain, doping, and heating is necessary, especially on the nanoscale. Here, we study clean devices consisting of membranes of single-layer MoS suspended on pillar arrays.

Magnetic bistability of a TbPc submonolayer on a graphene/SiC(0001) conductive electrode.

The alteration of the properties of single-molecule magnets (SMMs) due to the interaction with metallic electrodes is detrimental to their employment in spintronic devices. Conversely, herein we show that the terbium(iii) bis-phthalocyaninato complex, TbPc, maintains its SMM behavior up to 9 K on a graphene/SiC(0001) substrate, making this alternative conductive layer highly promising for molecular spintronic applications.