Control of Magnetic and Topological Orders with a DC Electric Field.

We theoretically propose a new route to control magnetic and topological orders in a broad class of insulating magnets with a DC electric field. We show from the strong-coupling expansion that magnetic exchange interactions along the electric-field direction are generally enhanced in Mott insulators. We demonstrate that several magnetic or topological ordered phases such as quantum spin liquids and Haldane-gap states can be derived if we apply a strong enough DC electric field to typical frustrated or low-dimensional magnets. Our proposal is effective especially for weak Mott insulators and magnets in the vicinity of quantum critical points, and would also be applicable for magnets under low-frequency AC electric fields such as terahertz laser pulses. A similar strategy of controlling exchange interactions can also be utilized in cold atomic systems.