Exchange bias controlled antisymmetric-symmetric magnetoresistances in Fe3GeTe2/graphite/Fe3GeTe2 trilayer

The magnetoresistance (MR) of spin values usually displays a symmetric dependence on the magnetic field. An antisymmetric MR phenomenon has been discovered recently that breaks the field symmetry and has the potential to realize multi-bit memory. In this work, we report a controllable switch between the antisymmetric and symmetric MRs and propose a multi-bit memory performance in Fe3GeTe2 (FGT)/graphite/FGT trilayer with modified vertical geometry. Via investigating the evolution of the antisymmetric MR depending on the spatial distribution, current direction, and magnetization configuration, we demonstrate that the antisymmetric MR results from the local nonequilibrium current through the trilayer. Furthermore, an exchange bias effect is induced which modifies the antisymmetric MR. A stable multi-bit memory is presented in the heterostructure. Such architecture for multi-state memory provides insights into other spin-valve structures to improve storage density.