Spin orbit torque effect in Pt/FeMn bilayers

Recently, there is an increasing interest in exploiting antiferromagnet (AFM) as an active element in spintronic devices arising from its advantages of negligible shape anisotropy and good thermal stability as compared to its ferromagnet (FM) counterpart. To reap these benefits of AFM, however, one must find a viable way to obtain sizable output signal from AFM and an efficient mechanism for reorienting its spin directions, both of which are known to be more difficult than that of FM. On the other hand, spin orbit torque in FM/heavy metal (HM) bilayers [1] has recently been reported to be a promising alternative to spin transfer torque for switching magnetization directly by an in-plane current. Although both theoretical and experimental investigations suggested that it is possible to alter the spin configuration of antiferromagnet by STT [2], it remains an open question as to whether the same can be achieved via SOT. In this work, we present the experimental investigations of SOT effect in Pt/FeMn bilayers. The Hall bar samples were fabricated using standard lift off and sputtering techniques. To quantify the SOT effect, two sets of planar Hall effect (PHE) measurements were performed: 1) at different bias currents (5–30 mA) with zero transverse bias field, 2) at different bias field (60–260 Oe) with 3 mA bias current.