Lighting up topological insulators: large surface photocurrents from magnetic superlattices

Gil Refael, Caltech

The gapless surface states of topological insulators (TI) can potentially be used to detect and harvest low-frequency infrared light. Nonetheless, it was shown that significant surface photocurrents due to light with frequency below the bulk gap are rather hard to produce. Adding a periodic magnetic pattern to the surface dramatically enhances surface photocurrents in TI's. The ability to produce substantial photocurrents on TI surfaces from mid-range and far-infrared light could be used in photovoltaic applications, as well as for detection of micrometer wavelength radiation.