Electric-field control of magnon spin current in an antiferromagnetic insulator*

A fundamental challenge in the development of spintronics is the effective control of spin currents by electrical means. This is because the spin degree of freedom is often decoupled from external electric fields, making its control difficult. Over the last few years, the spin Seebeck effect has shown its versatility in generating pure spin currents in a diverse class of magnetic systems. Here we first show how a magnon spin current can be produced in an antiferromagnetic insulator by means of the spin Seebeck effect. The polarity of the spin current is determined by the orientation of the magnetic sublattice in this antiferromagnet. Owning to the response of the magnetic ions to an external electric field, the anisotropy energy of this material may be effectively tuned. As a result, we show that the spin-flop transition in this material can be switched on or off by varying only an electrical voltage. Furthermore, we demonstrate how thermally generated spin currents in this antiferromagnet can be effectively controlled by sweeping the control voltage.