  We demonstrate a voltage-controlled exchange bias effect in CoFeB/MgO/CoFeB
magnetic tunnel junctions that is related to the interfacial Fe(Co)Ox 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.
