Circular photogalvanic effect on topological insulator surfaces: Berry-curvature-dependent response

Abstract

We study theoretically the optical response of the surface states of a topological insulator, especially the generation of helicity-dependent direct current by circularly polarized light. Interestingly, the dominant current, due to an interband transition, is controlled by the Berry curvature of the surface bands. This extends the connection between photocurrents and Berry curvature beyond the quasiclassical approximation where it has been shown to hold. Explicit expressions are derived for the (111) surface of the topological insulator Bi2Se3 where we find significant helicity dependent photocurrents when the rotational symmetry of the surface is broken by an in-plane magnetic field or a strain. Moreover, the dominant current grows linearly with time until a scattering occurs, which provides a means for determining the scattering time. The dc spin generated on the surface is also dominated by a linear-in-time, Berry curvature dependent contribution.

Floquet topological insulators

“…This spin-locking property allows a circularly polarized light to generate a DC rectified current at the surface of the insulator. Recently, Pavan Hosur pointed out that this socalled circular photogalvanic effect (CPE) can be used as a detection of a finite Berry curvature [32]. Indeed, in presence of the latter there is a contribution to the photocurrent that grows linearly in time before being cut-off (by a scattering event) after some relaxation time.…”

“…5 Photocurrent induced within a 2D surface state We now discuss the potentialities of using circularly polarized light to probe the surface state (SS) of a threedimensional (3D) topological insulator, like Bi 2 Se 3 , Bi 2 Te 3 , or strained HgTe [32,33].…”

“…In contrast, in presence of hexagonal warping, the spin is tilting out of the plane and the photocurrent will develop a current growing linearly in time. Besides, the CPE could also be used to probe the relaxation times in the SS of 3D TIs [32].…”

“…Section 4 describes our work on the photocurrent generated by shining an electromagnetic wave onto the helical edge states of a QSH insulator [31]. Finally, Section 5 reviews related works on the photocurrent generation in the surface states of 3D topological insulators [32,33]. driving.…”

Photon drag effect in(Bi1−xSbx)2Te3three-dimensional topological insulators

“…There have been many theoretical and experimental works in the past few years on helicity-controlled photocurrents [14][15][16][17][18], the linear photogalvanic effect [19][20][21], local photocurrents [22,23], edge photocurrents in two-dimensional (2D) TIs [24,25], coherent control of injection currents [26,27], photon drag currents [19,28,29], second-harmonic generation [30], photoinduced quantum Hall insulators [31,32], cyclotron-resonance-assisted photocurrents [33,34], quantum oscillations of photocurrents [35], photogalvanic currents via proximity interactions with magnetic materials [36][37][38], and the photoelectromagnetic effect [39]. These phenomena, scaling in the second or third order of the radiation electric fields, open up new opportunities to study Dirac fermions, which has been already demonstrated for graphene (for a review see Ref.…”