Room temperature electrically tunable terahertz Faraday effect

We demonstrate electrical control of the room temperature Faraday effect in a 100-nm-thick film of strained HgTe, which is a topological insulator. The terahertz (THz) response of our device is dominated by the Drude response of carriers with high mobility. The electrical control is achieved by gating the carrier density in a static magnetic field, opening new perspectives for applications like high-speed amplitude and phase modulators in the THz frequency range.