Light Induced Quantum Anomalous Hall Effect in Cubic Rashba Spin-Orbit Coupled Systems

TL;DR

This work demonstrates that off-resonant circularly polarized light can induce quantum anomalous Hall phases in a two-dimensional electron system with cubic Rashba spin–orbit coupling, yielding Chern numbers $C=0$, $1$, and $3$ through Floquet engineering. The topological transitions are driven by light-induced gap closings at Brillouin-zone high-symmetry points, with the phase diagram shaped by light intensity and photon energy, and further modulated by added linear Rashba or Dresselhaus couplings. Linear Rashba can introduce additional phases within narrow parameter windows, while linear Dresselhaus coupling can sustain nontrivial phases for any finite drive; high-Chern-number states originate from band inversions at X, Y, M and possibly Gamma. The results offer experimentally relevant routes to optically control topological phases and edge states in Floquet Chern insulators across conventional and engineered quantum platforms.

Abstract

We investigate topological phase transitions in a two-dimensional electron system with cubic Rashba spin-orbit coupling driven by circularly polarized light. Within the Floquet framework, we demonstrate that light-matter interaction induces nontrivial band topology characterized by a quantized anomalous Hall response, with Chern insulating phases of C = 0, 1, and 3. These transitions are governed by gap closings at high-symmetry points in the Brillouin zone, controlled by the intensity and energy of the incident light. Introducing a weak linear Rashba term displaces Dirac points in momentum space without modifying the topology, whereas a purely linear Rashba system remains topologically trivial (C = 0). When both linear and cubic Rashba couplings are finite, the linear term confines nonzero-Chern phases to narrow parameter windows. In contrast, incorporating a linear Dresselhaus term into the cubic Rashba system can trigger topological transitions even at small coupling strengths. These results clarify the interplay between distinct spin-orbit interactions in Floquet-engineered Chern insulators and offer experimentally relevant pathways for achieving light-controlled topological phases.

Figures (9)

• Figure 1: Momentum-space spin textures for three types of spin–orbit coupling: linear Rashba (left), linear Dresselhaus (middle), and cubic Rashba (right).
• Figure 2: The top panel shows the energy band structure and spin contours of the in-plane spin vector field $(S_x,S_y)$ for the case of cubic Rashba spin-orbit coupling. The blue and red lines represents the contours where $S_x=0$ and $S_y=0$, respectively. The energy dispersion is plotted as a function of $k_x$ with $k_y=0$. The band touching point at ${\bf k}=(0,0)$ indicates the presence of a nonlinear Dirac point, characteristic of cubic spin-orbit interaction. The middle panel is shown for both finite linear and cubic Rashba coupling. We fix $\alpha_R=0.3$ eV${\AA}$ and $\beta=0.5$ eV${\AA}^3$. The three black circles in spin contour plot are the position of linear Dirac points. The bottom panel is shown for both finite linear Dresselhaus and cubic Rashba coupling. We fix $\alpha_D=0.1$eV ${\AA}$ and $\beta=0.5$ eV ${\AA}^3$. The position of five Dirac points are shown in the spin contour plot by black circle. The energy diagram is shown at the point marked by a black big circle. The splitting of multiple Dirac points has also been discussed in Ref.Ji-PRB24.
• Figure 3: The anomalous hall conductivity $\sigma_{xy}$ is plotted as a function of $A_L$ for the case of cubic Rashba spin-orbit coupling. Here, we fix the parameters $\beta=0.5$ eV$\cdot$${\AA}^3$, and $\Delta_m=0.5$ eV.
• Figure 4: The left panel shows the energy spectrum with $k_x$ under open boundary conditions with parameters $\alpha_R=0.1$ eV${\AA}$, $\beta=0.5$ eV ${\AA}^3$ and $A_L=0.04$ eV$^{-1}$${\AA}^{-2}$. The red curves denote the edge states within the bulk band gap. The right panel displays the corresponding probability density profiles of these edge modes.
• Figure 5: Anomalous Hall conductivity as a function of the light coupling parameter $A_L$ at zero temperature for finite linear and cubic spin-orbit coupling strength. In the left panel, the parameters are fixed at $\alpha_R=1$ eV ${\AA}$, $\beta=0.5$ eV ${\AA}^3$. In the right panel, we set $\alpha_R=1$ eV ${\AA}$ and $\beta=0.2$ eV ${\AA}^3$, satisfying $\alpha_R> 4\beta$. In both panel $\Delta_m=0.2$ eV.