Tunable photogalvanic effect on topological insulator surfaces via proximity interactions

Abstract

An unusual photogalvanic effect is predicted on the topological insulator surface when its semimetallic electronic spectrum is modified by an adjacent ferromagnet. The effect is correlated with light absorption in a wide frequency range (from a few to hundreds of meV) and produces a pronounced response that is not only resonant to the photon energy but also tunable by an external electrical bias. The exceptionally strong peak photocurrent of the order of $\ensuremath{\mu}$A/cm may be achieved at elevated temperatures with the illumination power of 1 W/cm${}^{2}$ in the THz range on Bi${}_{2}$Se${}_{3}$. These advantages could enable room-temperature detection of far-infrared radiation.