Voltage control of perpendicular exchange bias in Pt/IrMn/Co/(Co/Pt)2/Ta/PMN-PT(011) multiferroic heterostructures

Exchange bias (EB), as an internal magnetic bias induced by a ferromagnetic-antiferromagnetic exchange coupling, is extremely important in many magnetic applications such as memories, sensors and other devices. Voltage control of exchange bias in multiferroics provides an energy-efficient way to achieve a rapidly 180° deterministic switching of magnetization, which has been considered as a key challenge in realizing next generation of fast, compact and ultra-low power magnetoelectric memories and sensors. Although there are some researches related to the voltage controlled EB, few of them focus on the regulation of perpendicular EB which is of great technological relevance for high-density spintronics. In this study, we demonstrated E-field control of perpendicular EB based on Pt 4nm/IrMn 4nm/Co 0.7 nm/(Co 0.7nm/Pt 0.95 nm)
₂
/Ta 3nm/PMN-PT (011) multiferroic heterostructure at room temperature. Angular dependences of EB with different applied voltage were studied through vibrating sample measurements (VSM) and ferromagnetic resonance (FMR) measurements respectively. For each method, maximal E-field induced exchange field change of ΔH
_eb
= 47 Oe and 95 Oe were obtained at θ=0° and 10° while under the compressive stress. Since VSM and FMR have different measurement principle, the difference of ΔH
_eb
is predictable. We related this phenomenon to the strain induced lattice distortion, which can influence the Co 3d - Pt 5d interfacial hybridization and then the change of interlayer exchange bias. This voltage manipulation of perpendicular EB should offer new possibilities towards novel magnetic devices and memories with great energy-efficiency and ultra-high densities.