271 citations · 1.4k across the 40 of their papers we have counts for
30 papers · 1 filter
Chiral electronic network within skyrmionic lattice on topological insulator surfaces
Matteo Wilczak, Dmitry K. Efimkin, Victor Gurarie
We consider a proximity effect between Dirac surface states of a topological insulator and the skyrmion phase of an insulating magnet. A single skyrmion results in the surface stat…
Theory of Band Gap Reduction Due to Conduction Electrons in 2D TMDs: Imaginary Frequency Formalism
Jack N. Engdahl, Harley D. Scammell, Dmitry K. Efimkin +1
Two Dimensional (2D) Transition Metal Dichalcogenides (TMDs) possess a large direct band gap which has been experimentally observed to shrink with increasing charge carrier density…
Valley-mediated singlet- and triplet-polaron interactions and quantum dynamics in a doped WSe monolayer
Yue Ni, Di Huang, Danfu Liang +11
In doped transition metal dichalcogenides, optically created excitons (bound electron-hole pairs) can strongly interact with a Fermi sea of electrons to form Fermi polaron quasipar…
Excitons in Atomically Thin TMD in Electric and Magnetic Fields
Jack N. Engdahl, Harley D. Scammell, Dmitry K. Efimkin +1
The magnetic field dependence of photoabsorption provides direct insights into the band structure of semiconductors. It is perhaps surprising that there is a large discrepancy betw…
Giant resonant skew scattering of plasma waves in a two-dimensional electron gas
Cooper Finnigan, Dmitry K. Efimkin
Electron skew scattering by impurities is one of the major mechanisms behind the anomalous Hall effect in ferromagnetic nanostructures. It is particularly strong at the surface of…
Topological hybrid electron-hole Cooper pairing
Alexander Chansky, Dmitry K. Efimkin
We consider electron--hole Cooper pair condensation in a heterostructure formed by a topological insulator film and a quantum well. We argue that the helical nature of the Dirac el…
Quantum Dynamics of Attractive and Repulsive Polarons in a Doped MoSe Monolayer
Di Huang, Kevin Sampson, Yue Ni +11
When mobile impurities are introduced and coupled to a Fermi sea, new quasiparticles known as Fermi polarons are formed. There are two interesting, yet drastically different regime…
Weyl excitations via helicon-phonon mixing in conducting materials
Dmitry K. Efimkin, Sergey Syzranov
Quasiparticles with Weyl dispersion can display an abundance of novel topological, thermodynamic and transport phenomena, which is why novel Weyl materials and platforms for Weyl p…
Exciton-polaron interactions in monolayer WS
Jack B. Muir, Jesper Levinsen, Stuart K. Earl +12
Interactions between quasiparticles are of fundamental importance and ultimately determine the macroscopic properties of quantum matter. A famous example is the phenomenon of super…
Rydberg Exciton-Polaritons in a Magnetic Field
Emma Laird, Francesca M. Marchetti, Dmitry K. Efimkin +2
We theoretically investigate exciton-polaritons in a two-dimensional (2D) semiconductor heterostructure, where a static magnetic field is applied perpendicular to the plane. To exp…
Equatorial magnetoplasma waves
Cooper Finnigan, Mehdi Kargarian, Dmitry K. Efimkin
Due to its rotation, Earth traps a few equatorial ocean and atmospheric waves, including Kelvin, Yanai, Rossby, and Poincare modes. It has been recently demonstrated that the mathe…
Hybrid dark excitons in monolayer
Hong Liu, Anny Pau, Dmitry K. Efimkin
Transition metal dichalcogenides have a rich exciton landscape consisting of a variety of bright and dark excitonic states. We consider the lowest-energy dark states in $\hbox{MoS}…
Topological spin-plasma waves
Dmitry K. Efimkin, Mehdi Kargarian
The surface of a topological insulator hosts Dirac electronic states with the spin-momentum locking, which constrains spin orientation perpendicular to electron momentum. As a resu…
Electron-exciton interactions in the exciton-polaron problem
Dmitry K. Efimkin, Emma K. Laird, Jesper Levinsen +2
Recently, it has been demonstrated that the absorption of moderately doped two-dimensional semiconductors can be described in terms of exciton-polarons. In this scenario, attractiv…
Anomalous drag in electron-hole condensates with granulated order
Hong Liu, Allan H. MacDonald, Dmitry K. Efimkin
We explain the strong interlayer drag resistance observed at low temperatures in bilayer electron-hole systems in terms of an interplay between local electron-hole-pair condensatio…
Tunneling and Fluctuating Electron-Hole Cooper Pairs in Double Bilayer Graphene
Dmitry K. Efimkin, G. William Burg, Emanuel Tutuc +1
A strong low-temperature enhancement of the tunneling conductance between graphene bilayers has been reported recently, and interpreted as a signature of equilibrium electron-hole…
Helical Network Model for Twisted Bilayer Graphene
Dmitry K. Efimkin, Allan H. MacDonald
In the presence of a finite interlayer displacement field bilayer graphene has an energy gap that is dependent on stacking and largest for the stable AB and BA stacking arrangement…
Topologically Protected Helical States in Minimally Twisted Bilayer Graphene
Shengqiang Huang, Kyounghwan Kim, Dmitry K. Efimkin +6
In minimally twisted bilayer graphene, a moir{é} pattern consisting of AB and BA stacking regions separated by domain walls forms. These domain walls are predicted to support count…
Fingerprints of Berry phases in the bulk exciton spectrum of a topological insulator
Andrew A. Allocca, Dmitry K. Efimkin, Victor M. Galitski
We examine excitons formed in the bulk of a topological insulator as the system is tuned via a parameter between topological and trivial insulating phases, arguing that nontrivial…
Exciton-polarons in doped semiconductors in a strong magnetic field
Dmitry K. Efimkin, Allan H. MacDonald
In previous work we have argued that the optical properties of moderately doped two-dimensional semiconductors can be described in terms of excitons dressed by their interactions w…
Many-Body Theory of Trion Absorption Features in Two-Dimensional Semiconductors
Dmitry K. Efimkin, Allan H. MacDonald
Recent optical studies of monolayer transition metal dechalcogenides have demonstrated that their excitonic absorption feature splits into two widely separated peaks at finite carr…
Transport of Dirac electrons in a random magnetic field in topological heterostructures
Hilary M. Hurst, Dmitry K. Efimkin, Victor Galitski
We consider the proximity effect between Dirac states at the surface of a topological insulator and a ferromagnet with easy plane anisotropy, which is described by the \emph{XY}-mo…
Anomalous Coulomb Drag in Electron-Hole Bilayers due to the Formation of Excitons
Dmitry K. Efimkin, Victor Galitski
Several recent experiments have reported an anomalous temperature dependence of the Coulomb drag effect in electron-hole bilayers. Motivated by these puzzling data, we study theore…
Charged skyrmions on the surface of a topological insulator
Hilary M. Hurst, Dmitry K. Efimkin, Jiadong Zang +1
We consider the interplay between magnetic skyrmions in an insulating thin film and the Dirac surface states of a 3D topological insulator (TI), coupled by proximity effect. The ma…