arXiv subjects

Rafi Bistritzer

Publications and source records attributed to Rafi Bistritzer.

6 recordsLinked to original sources

arXiv2026

Interaction driven charge transfer transitions in closely spaced graphene double layers

Charge transfer between two conductors is conventionally viewed as a single-particle process governed by electrostatics and band alignment. Using tunneling spectroscopy, we show that charge transfer in closely spaced graphene double layer quantum Hall ferromagnets instead proceeds through a sequence of interaction driven phase transitions governed by the competition between capacitive charging and Coulomb exchange interactions. A comparison of experimental data and theoretical calculations identifies spectroscopic signatures of the interaction driven charge transfer transitions, and reveals that this charge transfer reconstructs the quasiparticle spectrum. While intralayer exchange favors abrupt transfer of entire spin-valley subbands between the layers, interlayer exchange stabilizes coherent intermediate phases that enable gradual charge transfer. Our results establish interlayer tunneling as a powerful probe of interacting electronic systems whose quasiparticle spectrum is itself bias dependent.

cond-mat.mes-hall↗

arXiv2025

Miniband Generation by Surface Acoustic Waves

We introduce a new class of tunable periodic structures, formed by launching two obliquely propagating surface acoustic waves on a piezoelectric substrate that supports a two-dimensional quantum material. The resulting acoustoelectric superlattice exhibits two salient features. First, its periodicity is widely tunable, spanning a length scale intermediate between moir\'e superlattices and optical lattices, enabling the formation of narrow, topologically nontrivial energy bands. Second, unlike moir\'e systems, where the superlattice amplitude is set by intrinsic interlayer tunneling and lattice relaxation, the amplitude of the acoustoelectric potential is externally tunable via the surface acoustic wave power. Using massive monolayer graphene as an example, we demonstrate that varying the frequencies and power of the surface acoustic waves enables in-situ control over the band structure of the 2D material, generating flat bands and nontrivial valley Chern numbers, featuring a highly localized Berry curvature.

cond-mat.mes-hall↗

arXiv2010

Transport Between Twisted Graphene Layers

Commensurate-incommensurate transitions are ubiquitous in physics and are often accompanied by intriguing phenomena. In few-layer graphene (FLG) systems, commensurability between honeycomb lattices on adjacent layers is regulated by their relative orientation angle theta, which is in turn dependent on sample preparation procedures. Because incommensurability suppresses inter-layer hybridization, it is often claimed that graphene layers can be electrically isolated by a relative twist, even though they are vertically separated by a fraction of a nanometer. We present a theory of interlayer transport in FLG systems which reveals a richer picture in which the specific conductance depends sensitively on theta, single-layer Bloch state lifetime, in-plane magnetic field, and bias voltage. We find that linear and differential conductances are generally large and negative near commensurate values of theta, and small and positive otherwise.

cond-mat.mes-hall↗

arXiv2008

Room-Temperature Superfluidity in Graphene Bilayers

Because graphene is an atomically two-dimensional gapless semiconductor with nearly identical conduction and valence bands, graphene-based bilayers are attractive candidates for high-temperature electron-hole pair condensation. We present estimates which suggest that the Kosterlitz-Thouless temperatures of these two-dimensional counterflow superfluids can approach room temperature.

cond-mat.mes-hall↗

arXiv2006

Intrinsic dephasing in one dimensional ultracold atom interferometers

Quantum phase fluctuations play a crucial role in low dimensional systems. In particular they prevent true long range phase order from forming in one dimensional condensates, even at zero temperature. Nevertheless, by dynamically splitting the condensate into two parallel decoupled tubes, a macroscopic relative phase, can be imposed on the system. This kind of setup can serve as a matter wave interferometer, which relies on the interference between the displaced condensates as a measure of the relative phase between them. Here we show how the quantum phase fluctuations, which are so effective in equilibrium, act to destroy the macroscopic relative phase that was imposed as a non equilibrium initial condition of the interferometer. We show that the phase coherence between the two condensates decays exponentially with a dephasing time that depends on intrinsic parameters: the dimensionless interaction strength, sound velocity and density. Interestingly, at low temperatures the dephasing time is almost independent of temperature. At temperatures higher than a crossover scale T* dephasing gains significant temperature dependance. In contrast to the usual phase diffusion, which is essentially an effect of confinement, the dephasing due to fluctuations in one dimension is a bulk effect that survives the thermodynamic limit.

cond-mat.other↗

arXiv2005

The physical picture behind the oscillating sign of drag in high Landau levels

We consider the oscillating sign of the drag resistivity and its anomalous temperature dependence discovered experimentally in a bi-layer system in the regime of the integer quantum Hall effect. We attribute the oscillating sign to the effect of disorder on the relation between an adiabatic momentum transfer to an electron and the displacement of its position. While in the absence of any Landau level mixing a momentum transfer $\hbar \bf q$ implies a displacement of $ql_H^2$ (with $l_H$ being the magnetic length), Landau level mixing induced by short range disorder adds a potentially large displacement that depends on the electron's energy, with the sign being odd with respect to the distance of that energy from the center of the Landau level. We show how the oscillating sign of drag disappears when the disorder is smooth and when the electronic states are localized.

cond-mat.mes-hall↗