Topological edge-state engineering with high-frequency electromagnetic radiation

Strong interaction with light may modify quantitatively the electronic properties of condensed matter systems. Here, the authors consider the classical example of topological electron states in a CdTe/HgTe/CdTe heterostructure and demonstrate that the coupling between electrons in a two-dimensional region and an external electromagnetic wave controls with high accuracy the normal and topological phases in the system. The electromagnetic radiation also modifies the properties of the edge states, which leads to the reversal of the edge spin currents. Importantly, all these effects can be realized in controllable and reversible way, and this has high potential impact for their integration of spintronics and optoelectronics.