3 research outputs found
Switching on surface conduction in a topological insulator
The protected surface conductivity of topological insulators, carried by
ultra-relativistic Dirac fermions, is in high demand for the next generation of
electronic devices. Progress in the unambiguous identification of this surface
contribution and, in a second step, its control are needed to move forward.
Here we demonstrate both, with a combined transport and spectroscopy study of
high-quality single crystals and mesoscopic devices of the topological
insulator TlBiSe2. We show how various external stimuli-from thermal radiation,
via low-intensity light, to high-intensity laser pumping and current
driving-can boost the surface contribution, thereby making it both
unambiguously detectable and potentially exploitable for applications. Once
switched on, the extra surface contribution is persistent, with lifetimes of
hundreds of years at low temperatures. We understand this effect in terms of
the well-known concept of surface charge accumulation via a Schottky barrier
formation, and propose that the same mechanism underlies also the slow
relaxations seen with spectroscopic probes in our and other materials, which
might thus also be persistent. We expect our technique to be readily
transferable to other materials and probes, thereby shedding light on
unexplained slow relaxations in transport and beyond