Magnetic Field Dependent Effects on Nonlocal Photocurrents in Topological Insulators

Topological insulators (TIs) are a remarkable class of materials due to their linear dispersion relation owing to their time-reversal symmetry-protected Dirac Cones, which have recently displayed millimeter-long diffusion lengths with a highly tunable Fermi level. Motivated by the hypothesis that these highly extended photocurrents are likely reliant on the topological surface states, we perform illuminated magnetoresistance studies on Sb-doped Bi2Se3 as a function of temperature, gate voltage, and field angle of incidence to study photo-doped weak antilocalization and Aharanov-Bohm effect behaviors. Our results provide clues about the nature of the carriers responsible for these remarkably nonlocal photocurrents which may be due to the carrier states forming an exciton condensate.