Confocal Raman spectroscopy is a versatile, non-invasive investigation tool and major workhorse for graphene characterization. Here we show that the experimentally observed 2D line width measure of nanometer-scale strain variations in graphene. By investigating relation between G at high magnetic fields find contains valuable information on flatness lattice deformations graphene, making it good quantity classifying structural quality even zero field.

One of the fundamental properties semiconductors is their ability to support highly tunable electric currents in presence fields or carrier concentration gradients. These are described by transport coefficients such as electron and hole mobilities. Recently, advances electronic structure methods for real materials have made it possible study these with predictive accuracy without resorting empirical parameters. Here, we review most recent developments area ab initio calculations mobilities...

Emerging reconfigurable devices are fast gaining popularity in the search for next-generation computing hardware, while ferroelectric engineering of doping state semiconductor materials has potential to offer alternatives traditional von-Neumann architecture. In this work, we combine these concepts and demonstrate suitability field-effect transistors (Re-FeFETs) designing nonvolatile logic-in-memory circuits with multifunctional capabilities. Modulation energy landscape within a homojunction...

There are a number of theoretical proposals based on strain engineering graphene and other two-dimensional materials, however purely mechanical control fields in these systems has remained major challenge. The two approaches mostly used so far either couple the electrical properties system simultaneously or introduce some unwanted disturbances due to substrate. Here, we report silicon micromachined comb-drive actuators controllably reproducibly induce suspended sheet an entirely way. We use...

We present a combined experimental and theoretical study of resonant Raman spectroscopy in single- triple-layer MoTe$_2$. intensities are computed entirely from first principles by calculating finite differences the dielectric susceptibility. In our analysis, we investigate role quantum interference effects electron-phonon coupling. With this method, explain experimentally observed intensity inversion $A^\prime_1$ vibrational modes MoTe2 with increasing laser photon energy. Finally, show...

The energy transition has resulted in the integration of power-intensive consumers and producers into low voltage grids. This led to an increased load on these grids, which may reach their capacity limits thus necessitate grid expansions. However, expansions cannot be completed a short-term period due various limitations. project DIGITECHNETZ focuses digital transformation grids proposes different use cases for active management. core component this is data platform that provides essential...

The coupling between excitons and phonons across adjacent layers has been experimentally observed in various heterostructures of layered materials. However, the precise mechanism underlying this phenomenon remains elusive. Using WSe2@hBN heterostructure as an example, we study origin interlayer exciton-phonon its signature resonant Raman scattering through first-principles calculations. Our emphasizes central role crystal symmetries processes, which are responsible for anomalous intensities...

We present magneto-Raman spectroscopy measurements on suspended graphene to investigate the charge carrier density-dependent electron-electron interaction in presence of Landau levels. Utilizing gate-tunable magneto-phonon resonances, we extract density dependence level transition energies and associated effective Fermi velocity $v_\mathrm{F}$. In contrast logarithmic divergence $v_\mathrm{F}$ at zero magnetic field, find a piecewise linear scaling as function density, due field-induced...

We present a method to create and erase spatially resolved doping profiles in graphene-hexagonal boron nitride (hBN) heterostructures. The technique is based on photo-induced by focused laser does neither require masks nor photo resists. This makes our interesting for rapid prototyping of unconventional electronic device schemes, where the spatial resolution rewritable, long-term stable only limited spot size (~600 nm) accuracy sample positioning. Our optical offers way implement test...

Many-body effects resulting from strong electron-electron and electron-phonon interactions play a significant role in graphene physics. We report on their manifestation low B field magneto-phonon resonances high-quality exfoliated single-layer bilayer encapsulated hexagonal boron nitride. These allow us to extract characteristic effective Fermi velocities, as high 1.20 × 10(6) m/s, for the observed "dressed" Landau level transitions, well broadening of resonances, which increases with index.

Abstract The Raman 2D line of graphene is widely used for device characterization and during fabrication as it contains valuable information on, e.g., the direction magnitude mechanical strain doping. Here, we present systematic asymmetries in shape exfoliated grown by chemical vapor deposition. Both crystals are fully encapsulated van der Waals heterostructures, where hexagonal boron nitride tungsten diselenide substrate materials. In both material stacks, find very low doping values...

We develop a new computational approach to resonant Raman scattering study nonadiabatic exciton-phonon scattering.

We present a thermal annealing study on single‐layer and bilayer (BLG) graphene encapsulated in hexagonal boron nitride. The samples are characterized by electron transport Raman spectroscopy measurements before after each step. While extracted material properties such as charge carrier mobility, overall doping, strain not influenced the annealing, an initial step lowers doping variations thus results more homogeneous sample. Additionally, narrow 2D‐sub‐peak widths of spectrum BLG, allow us...

Abstract Ba(Zr,Hf)S 3 solid solutions are proposed for photovoltaic applications and a fast non‐destructive measurement of the composition these identification any possible secondary phases is prerequisite understanding their opto‐electronic properties. Previously multi‐wavelength Raman spectroscopy has been used such purposes in other chalcogenide solution series. Here we calculate non‐resonant one‐phonon spectra pure BaHfS BaZrS , which show only subtle differences between them, since most...

${\mathrm{BiFeO}}_{3}$ is a technologically relevant multiferroic perovskite featuring ferroelectricity and antiferromagnetism. Its lattice, magnetic, ferroelectric degrees of freedom are coupled to its optically active excitations thus hold the potential be reversibly probed controlled by light. In this work, we combine ab initio density functional many-body perturbation theory methods with an extensive symmetry atomic-orbital analysis describe understand electronic excited states spectrum...

We present the results of a diagrammatic, fully ab initio calculation $G$ peak intensity graphene. The flexibility and generality our approach enables us to go beyond previous analytical calculations in low-energy regime. study laser Fermi energy dependence analyze contributions from resonant non-resonant electronic transitions. In particular, we explicitly demonstrate importance quantum interference states for process. Our method analysis computational concept is completely general can...

We explore the tunability of phonon polarization in suspended uniaxially strained graphene by magneto-phonon resonances. The uniaxial strain lifts degeneracy LO and TO phonons, yielding two cross-linearly polarized modes a splitting Raman G peak. utilize strong electron–phonon coupling off-resonant to resonance induce gate-tunable circular dichroism. This, together with strain-induced peak, allows us controllably tune linearly mode phonons into modes. are able achieve up 40% purely...

We develop a general, fully quantum mechanical theory of Raman scattering from first principles in terms many-body correlation functions. In order to arrive at expressions that are practically useful the context condensed matter physics, we adopt Lehmann-Symanzik-Zimmermann reduction formula high-energy physics and formulate modern language perturbation theory. This enables us derive general expression for rate quantities can be computed \textit{ab initio}. Our work paves way toward...

Graphene is an ideal platform to study the coherence of quantum interference pathways by tuning doping or laser excitation energy. The latter produces a Raman profile that provides direct insight into lifetimes intermediate electronic excitations and, therefore, on interference, which has so far remained elusive. Here, we control scattering energy in graphene doped up 1.05 eV. G mode indicates its position and full width at half-maximum are linearly dependent doping. Doping-enhanced...

We present a magneto-Raman study on high-quality single-layer graphene grown by chemical vapor deposition (CVD) that is fully encapsulated in hexagonal boron nitride dry transfer technique. By analyzing the Raman D, G, and 2D peaks, we find structural quality of samples comparable with state-of-the-art exfoliated flakes. From B-field dependent measurements, extract broadening associated lifetime G peak due to anharmonic effects. Furthermore, determine decay width Landau level (LL)...

We present Raman spectroscopy measurements of non-etched graphene nanoribbons, with widths ranging from 15 to 160 nm, where the D-line intensity is strongly dependent on polarization direction incident light. The extracted edge disorder correlation length approximately one order magnitude larger than previously reported ribbons fabricated by reactive ion etching techniques. This suggests a more regular crystallographic orientation here presented. further report width dependence line-width...