  Perpendicular exchange bias (EB), which combines the perpendicular magnetic
anisotropy and the ferromagnetic (FM) - antiferromagnetic (AFM) exchange
coupling, is extremely important in the high-density AFM spintronics. However,
the effective modulation of EB remains challenging, since the alternant spins
at the AFM/FM interface are strongly pinned by the AFM layer. Voltage tuning of
EB through the magnetoelectric coupling provides a potential way to achieve a
rapid magnetization switching in an energy-efficient manner. Nevertheless, the
interfacial strain mediation of perpendicular EB induced by E-field remains
unexplored. In this work, we obtain perpendicular EB nanostructure by
room-temperature fabrication process, and demonstrate the voltage tunable
perpendicular EB in Pt/IrMn/(Co/Pt)2/Ta/(011) Pb(Mg1/3Nb2/3)O3-PbTiO3
multiferroic heterostructure. To enhance the voltage control effect on
perpendicular EB, we further investigate both strain-mediated magnetoelectric
coupling and ionic liquid gating method in the thinned EB system with the
structure of Pt/IrMn/Co/Pt/Ta. As a result, the voltage induced lattice
distortion effectively transmits to the AFM/FM interface, while the charge
accumulation in gating method generates a relatively large hysteresis loop
offset that has not been observed before at room temperature. The voltage
manipulation of perpendicular EB at room temperature provides new possibilities
towards novel AFM devices and memories with great energy-efficiency and
ultra-high density.
