Manipulation of perpendicular exchange bias effect in [Co/Ni]_N/(Cu, Ta)/TbCo multilayer structures

With the demand for increasing storage density in spintronic applications, extensive work has been devoted to searching for perpendicular magnetic material systems with strong exchange bias effect. In this study we have investigated the exchange bias effect in perpendicular magnetized heterostructures of [Co/Ni]_N/(Cu, Ta)/TbCo. An interlayer of 0.8 nm Cu is capable of achieving separate magnetization switching, showing a quite large exchange bias field over 2.9 kOe. With increasing the interlayer thickness, both the Co/Ni bias field and TbCo switching field decrease much more rapidly for the samples with a Ta interlayer as compared to the Cu case, due to the better coverage ability of the amorphous nature. The influence of layer thickness and composition of the FM and FI layers has also been investigated and the variation tendencies are well interpreted.