SFB Extra Seminar

In electronics, the information about the magnetic state of the material could be used not only for information storage but also added to information processing, which would lead to new functionalities of the electronic components. Novel spin-based electronic devices which include the magnetic information for their operation are based on purely electrical mechanisms for switching of the magnetization. A promising current-induced switching mechanism is via the spin-orbit torque (SOT) that can occur, for example, at the interface of heavy metal (HM)/ ferromagnet (FM) bilayers.
In this talk I will present a study of an epitaxial HM/FM system containing layers of Au and Fe grown on the MgO(001) single crystal. With the layers sequence Au/Fe/MgO(001) we circumvent the segregation of Au atoms, typically observed in Fe/Au systems, therefore ensure the structural asymmetry and aim for a well de ned epitaxial HM/FM interface. Magneto-transport measurements of the lithographically patterned Au/Fe bilayers con-rm a strong in-plane easy magnetization axis and a cubic magnetic anisotropy in the lm plane dominated by the magneto-crystalline term of the single-crystalline Fe(001) layer. At room temperature, we nd that an in-plane current density beyond 1.4
107 A/cm2 can be employed for reproducible electrical switching of the magnetization between multiple stable states, which correspond to di erent arrangements of magnetic domains. Using Kerr microscopy we observed that the change of the domain structure scales with the applied current and can be read-out as a change in the transversal resistance measured via the planar Hall e ect (PHE).
The physical mechanism of the observed switching mechanism can be fully explained by the Oersted eld from the applied charge current. However, at temperatures below 50 K, PHE measurements indicate a presence of an additional current-induced eld up to 2.5 mT along the lm normal, which suggests a presence of SOT at low temperatures in the Au/Fe bilayer, a candidate for a model epitaxial HM/FM system.