Tunable photo-galvanic effect on topological insulator surfaces via proximity interactions

TL;DR

This paper predicts a tunable photo-galvanic effect on topological insulator surfaces influenced by ferromagnetic proximity, enabling potential room-temperature detection of far-infrared radiation with strong, resonant photocurrents.

Contribution

It introduces a novel, tunable photo-galvanic effect on topological insulators modified by ferromagnetic proximity, with potential applications in infrared detection.

Findings

Resonant photocurrent can reach microampere levels at elevated temperatures.

Effect is tunable by external electrical bias.

Strong response in the THz frequency range.

Abstract

An unusual photo-galvanic effect is predicted on the topological insulator surface when its semi-metallic 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 $\mu$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.