Laser-induced modulation of the Landau level structure in single-layer graphene

Abstract

International audienceWe present perturbative analytical results of the Landau level quasienergy spectrum, autocorrelation function, and out-of-plane pseudospin polarization for a single graphene sheet subject to intense circularly polarized Terahertz radiation. For the quasienergy spectrum, we find a striking nontrivial level-dependent dynamically induced gap structure. This photoinduced modulation of the energy band structure gives rise to shifts of the revival times in the autocorrelation function and it also leads to modulation of the oscillations in the dynamical evolution of the out-of-plane pseudospin polarization, which measures the angular momentum transfer between light and graphene electrons. For a coherent state, chosen as an initial pseudospin configuration, the dynamics induces additional quantum revivals of the wave function that manifest as shifts of the maxima and minima of the autocorrelation function, with additional partial revivals and beating patterns. These additional maxima and beating patterns stem from the effective dynamical coupling of the static eigenstates. We discuss the possible experimental detection schemes of our theoretical results and their relevance in new practical implementation of radiation fields in graphene physics

Photoinduced electronic and spin properties of two-dimensional electron gases with Rashba spin-orbit coupling under perpendicular magnetic fields

“…For small values of the renormalized SO interaction relative to the cyclotron energy, the energy levels are distributed as Zeemansplit pairs of Landau levels. Once the effect of the magnetic field on the SO coupling becomes relevant, each pair of levels splits off [note that, similar to the case of graphene [35,36], the level with quantum numbers (0, +) is independent of the SO coupling]. The energy spectrum then presents nonequidistant levels.…”

“…in the spin polarization as a function of time is either related to spin flipping due to Rashba SO interaction or to fluctuations in the excitation number due to the periodic driving. This initial state has been considered previously to study photoinduced effects on the Landau levels of monolayer graphene [36]. We now explore the effect on the dynamics of "real" spin by the interplay of photoinduced renormalized Rashba SO interaction and Zeeman term.…”

Photoinduced Pseudospin Dynamical Effects in Graphene-Like Systems

“…[23] where we theoretically analyse the dynamical manipulation of the LL structure of charge carriers on suspended monolayer graphene when a periodically driving radiation field is applied perpendicular to the sample. For this purpose, we focus on the low-energy properties of non-interacting spinless charge carriers in a suspended monolayer graphene subject to a perpendicular, uniform and constant magnetic field B ¼ Bẑ.…”

“…This Hamiltonian can be treated via non-degenerate perturbation theory to find the approximate quasi-energy spectrum (see Ref. [23] for details on the derivation), which read …”

“…In Section 2, we describe the Landau levels (LLs) in graphene when a laser is incident perpendicularly to the sample [23]. We show that an exact effective Floquet Hamiltonian can be found from which the dynamics is afterwards described [24][25][26].…”