Related papers: Gate tunable charged-phonon effect in bilayer grap…
Materials with massless Dirac fermions can possess exceptionally strong and widely tunable optical nonlinearities. Experiments on graphene monolayer have indeed found very large third-order nonlinear responses, but the reported variation of…
The optical properties of graphene are strongly affected by electron-electron (e-e) and electron-hole (e-h) interactions. Here we tune these many-body interactions through varying the density of free charge carriers. Measurements from the…
We compute, from first-principles, the frequency of the E2g, Gamma phonon (Raman G-band) of graphene, as a function of the charge doping. Calculations are done using i) the adiabatic Born-Oppenheimer approximation and ii) time-dependent…
We report low-temperature measurements of two adjacent, gate-defined Josephson junctions (JJs) in magic-angle twisted bilayer graphene (MATBG) at a moir\'e filling factor near $\nu = -2$. We show that both junctions exhibit a prominent,…
In superconducting copper oxides some Cu-O bond-stretching phonons around 70meV show anomalous giant softening and broadening of electronic origin and electronic dispersions have large renormalization kinks near the same energy. These…
The band structure of bilayer graphene is tunable by introducing a relative twist angle between the two layers, unlocking exotic phases, such as superconductor and Mott insulator, and providing a fertile ground for new physics. At…
Generating photogalvanic effects in centrosymmetric materials can provide new opportunities for developing passive photodetectors and energy harvesting devices. In this work, we investigate the photogalvanic effects in centrosymmetric…
We present a systematic theory of acoustic-phonon-mediated superconductivity, which incorporates Coulomb repulsion, explaining the recent experiment in Bernal bilayer graphene under a large displacement field. The acoustic-phonon mechanism…
Recent experiments demonstrated that proton transport through graphene electrodes can be accelerated by over an order of magnitude with low intensity illumination. Here we show that this photo-effect can be suppressed for a tuneable…
We demonstrate electrochemical top gating of graphene by using a solid polymer electrolyte. This allows to reach much higher electron and hole doping than standard back gating. In-situ Raman measurements monitor the doping. The G peak…
We develop an analytic theory to describe the interaction between electrons and K-phonons and study its influence on superconductivity in the bare bands of twisted bilayer graphene (TBG). We find that, due to symmetry and the two-center…
Quest for new states of matter near an ordered phase is a promising route for making modern physics forward. By probing thermal properties of a ferroelectric (FE) crystal Ba1-xSrxAl2O4, we have clarified that low-energy excitation of…
Understanding the origin of superconductivity in correlated two-dimensional materials is a key step in leveraging material engineering techniques for next-generation nanoscale devices. The recent demonstration of superconductivity in Bernal…
Thermoelectric power of a material, typically governed by its band structure and carrier density, can be varied by chemical doping that is often restricted by solubility of the dopant. Materials showing large thermoelectric power are useful…
We calculate the effect of the electron-phonon interaction on the electronic density of states (DOS), the quasiparticle properties and on the optical conductivity of graphene. In metals with DOS constant on the scale of phonon energies, the…
Magic-angle twisted bilayer graphene exhibits a panoply of many-body phenomena that are intimately tied to the appearance of narrow and well-isolated electronic bands. The microscopic ingredients that are responsible for the complex…
We study the effect exerted by the electrons on the flexural phonons in graphene, accounting for the attractive interaction created by the exchange of electron-hole excitations. Combining the self-consistent computation of the phonon…
We present a theory of phonon-mediated superconductivity in near magic angle twisted bilayer graphene. Using a microscopic model for phonon coupling to moir\'e band electrons, we find that phonons generate attractive interactions in both…
Significant excitonic effects were observed in graphene by measuring its optical conductivity in a broad spectral range including the two-dimensional {\pi}-band saddle-point singularities in the electronic structure. The strong…
An experimental study of Raman scattering in N-layer graphene as a function of the top layer doping is reported. At high doping level, achieved by a CHF_3 plasma treatment, we observe a splitting of the $G$ band in the spectra of bilayer…