Related papers: Moir\'{e} optical phonons dancing with heavy elect…
Correlated insulators and superconductivity have been observed in "magic-angle" twisted bilayer graphene, when the nearly flat bands close to neutrality are partially filled. While a momentum-space continuum model accurately describes these…
Perturbations in moir\'e materials, such as due to substrates or strain, are common in many experiments and can significantly modify the electronic properties of the system. Here, we show that perturbations in twisted bilayer graphene tend…
We give a self contained review of a recently developed strong coupling theory of magic-angle graphene. An advantage of this approach is that a single formulation can capture both the insulating and superconducting states, and with a few…
Following the work in graphene, we report a first-principles study of electron-phonon coupling (EPC) in low-buckled (LB) monolayer silicene and germanene. Despite of the similar honeycomb atomic arrangement and linear band dispersion, the…
The elastic collective modes of a moir\'e superlattice arise not from vibrations of a rigid crystal but from the relative displacement between the constituent layers. Despite their similarity to acoustic phonons, these modes, called…
Flat band electronic modes are responsible for superconductivity in twisted bilayer graphene (TBG) rotated at magic angles. From there other magic angles can be found for any multilayered twisted graphene systems. Eventually, this lead to…
We examine the interplay between electron correlations and phonons in an Anderson-Holstein impurity model with an Einstein phonon. When the phonons are slow compared to charge fluctuations (frequency $\omega_0 \ll U/2$, the onsite Coulomb…
Recently, artificial moire superlattices of classical waves have aroused tremendous interest, inspired by the newly emergent twistronics that focuses on the peculiar electronic properties induced by flat bands. However, so far, the moire…
We develop a theoretical framework for probing moir\'e phonon modes using Raman spectroscopy, and illustrate it with the example of twisted bilayer graphene (TBG). These moir\'e phonons arise from interlayer sliding motion in twisted 2D…
If we stack up two layers of graphene while changing their respective orientation by some twisting angle, we end up with a system that has striking differences when compared to single-layer graphene. For a very specific value of this twist…
The recent discovery of correlated insulator states and superconductivity in magic-angle twisted bilayer graphene has paved the way to the experimental investigation of electronic correlations in tunable flat band systems realized in…
When two graphene layers are rotated from AA or AB configuration by a small angle, the band structure changes dramatically. Numerical calculations have shown that, at certain discrete angles called magic angles, the low energy bands become…
In disordered lattices, itinerant electrons typically undergo Anderson localization due to random phase interference, which suppresses their motion. By contrast, in flat-band systems where electrons are intrinsically localized owing to…
We investigate the effect of electron-phonon interactions (EPI) in systems exhibiting one or more flat electron bands close to the Fermi level and a comparatively large phonon energy scale. After solving the self-consistent full-bandwidth…
Thanks to the recent discovery on the magic-angle bilayer graphene, twistronics is quickly becom11 ing a burgeoning field in condensed matter physics. This letter expands the realm of twistronics to acoustics by introducing twisted bilayer…
Bilayer graphene twisted by a small angle shows a significant charge modulation away from neutrality, as the charge in the narrow bands near the Dirac point is mostly localized in the regions of the Moir\'e pattern with $AA$ stacking. The…
We develop a low-energy continuum model to describe the moir\'{e} physics of heterostructures, which is a generalization of the celebrated Bistritzer-MacDonald (BM) method [R. Bistritzer and A. H. MacDonald, Proc. Natl. Acad. Sci. U.S.A.…
We theoretically study the piezoelectric effects in moir\`e graphene systems. Since the strain couples to the electrons in the system as a pseudo vector potential, which has opposite signs for the $K$ and $K'$ valleys of graphene, its…
We consider twisted bilayer graphene on a transition metal dichalcogenide substrate, where proximity-induced spin-orbit coupling significantly alters the eight flat bands which occur near the magic angle. The resulting band structure…
Twisted bilayer graphene is a rich condensed matter system, which allows one to tune energy scales and electronic correlations. The low-energy physics of the resulting moir\'e structure can be mathematically described in terms of a…