The development of antiferromagnetic (AFM) spintronics is an active field with great potential for improving energy consumption, reducing interference and decreasing sizes when compared to traditional spintronics. This requires the development of novel concepts and functionalities which allow control over the properties of a device containing an AFM layer.
We present in this work a new device concept in which the spin configuration of an AFM insulator (FeF2) can be modified taking advantage of spin-orbit coupling (SOC) existing in heavy metals (HM) such as W or Pt. The device consists of a trilayer: HM|AFM|FM, therefore the top FM interface can be used to monitor the changes in the AFM spin configuration.
We performed Magneto-Optical Kerr effect (MOKE) to measure the FM hysteresis loops as a function of temperature (T) and applied current (I). We found that the exchange bias (EB) and coercivity (Hc) produced at the AFM-FM top interface can be strongly modified by a current (I) passed through the HM|AFM bottom interface. This shows that an active spin-orbit torque (SOT) is produced at the HM|AFM bottom interface that reaches the AFM|FM top interface and modifies the reversal of the FM layer. Temperature-dependent control experiments using normal metals (NM) such as Au in NM|AFM|FM and without AFM in HM|FM confirm that the effect is produced by the SOT induced by the HM and is not caused by thermal heating, Oersted field or other potentially spurious effects.
This research was supported by the Department of Energy’s Office of Basic Energy Science, under grant # DE-FG02-87ER45332.