We demonstrate a voltage-controlled exchange bias effect in CoFeB/MgO/CoFeB magnetic tunnel junctions that is related to the interfacial Fe(Co)O_x formed between the CoFeB electrodes and the MgO barrier. The unique combination of interfacial antiferromagnetism, giant tunneling magnetoresistance, and sharp switching of the perpendicularly-magnetized CoFeB allows sensitive detection of the exchange bias. It is found that the exchange bias field can be isothermally controlled by magnetic fields at low temperatures. More importantly, the exchange bias can also be effectively manipulated by the electric field applied to the MgO barrier due to the voltage-controlled antiferromagnetic anisotropy in this system. (a), Representative TMR curves measured under different bias voltages at 30 K. (b), The voltage dependence of magnetization switching fields H_C1 and H_C2 at RT, as a result of the VCMA effect. (c), The voltage dependence of H_C1 and H_C2 at 30K, as a result of both the VCMA and voltage-controlled exchange bias effects. (d), Voltage dependence of the exchange bias field at 30K. Experimental data are fitted using equation (1) assuming a linear voltage dependence for K_AF.

• Magnons in anitiferromagnets can deliver orders of magnitude larger spin torques than conduction electrons

• Self-induced temperature gradient by relaxation of tunneling electrons reaches 1-2K/nm

• Very efficient switching in MTJ with AF barrier can be potentially achieved

• Calculation has been done by our collaborators ( Shufeng Zhang group)