Control of Photogalvanic Currents in Topological Insulator Metamaterials

Under circularly polarized light illumination, Dirac surface electrons in topological insulators show a natural chiral response due to spin-momentum locking, which can be interrogated by probing the dependence of photocurrent on the polarization of incident light. Here we report, for the first time, that patterning topological insulator BSTS (Bi 1.5 Sb 0.5 Te 1.8 Se 1.2 ) crystals with mirror-symmetric, planar-chiral metamaterial designs generates giant enhancement and reversal of photogalvanic currents.