| AVS 64th International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures Division | Monday Sessions |
| Session MI+BI+EM+SA-MoA |
| Session: | Role of Chirality in Spin Transport and Magnetism |
| Presenter: | Arantzazu Mascaraque, Universidad Complutense de Madrid, Spain |
| Authors: | A. Mascaraque, Universidad Complutense de Madrid, Spain S. Ruiz-Gomez, Universidad Complutense de Madrid, Spain M.A. Gonzalez Barrio, Universidad Complutense de Madrid, Spain L. Perez, Universidad Complutense de Madrid, Spain G. Chen, Lawrence Berkeley National Laboratory A.K. Schmid, Lawrence Berkeley National Laboratory E.G. Michel, Universidad Autonoma de Madrid, Spain |
| Correspondent: | Click to Email |
The possibility of manipulating magnetic domain walls (DWs) without the intervention of magnetic fields has interest for a wide variety of applications, such as spintronic devices [1]. Applying an electric current to a ferromagnet creates a force that drives the DWs in the direction of the electron motion, the so-called Spin Transfer Torque. However, this effect is weak and high current densities are needed. Recently, it has been discovered that spin accumulation at the edges of a current-carrying non-magnetic material due to the Spin Hall Effect (SHE), can exert a torque on the magnetization of a neighboring magnetic layer [2]. The torque induced by SHE depends on the chirality of the DW and, as most ferromagnetic materials lack a well-defined chirality, the device applications are limited. However, the presence of surfaces and interfaces removes the point-inversion symmetry, giving rise to an additional interaction, the Dzyaloshinskii–Moriya interaction (DMI) that lifts the left-right degeneracy through spin-orbit coupling [3].
In this work, we have modified the interface between the substrate and a non-chiral magnetic layer, in order to investigate in which way DW chirality can be induced and stabilized in the magnetic layer. The experiments were done using the SPLEEM instrument of the Lawrence Berkeley National Laboratory. This microscope can map independently and in real space the three magnetic components of the spin structures. The magnetic system was a (Ni/Co)n multilayer epitaxially grown on Cu(111). It is well known that magnetic films grown on Cu(111) do not exhibit homo-chiral DWs [4]. We have found that this behavior can be changed by modifying the interface. After introducing a thin metal layer (suitable to induce a high DMI) between the substrate and the magnetic layer, we have found relevant changes in the chirality of the DWs of the magnetic layer. Our results demonstrate that the buffer layer influences the spin texture, which evolves from non-chiral Bloch to homo-chiral Néel DWs.
[1] S. S. P. Parkin et al, Science 320, pp190 (2008); D. A. Allwood et al , Science 309 , pp1688 (2005)
[2] I. M. Miron Nat. Mat 9 pp230 (2010)
[3] I. E. Dzyaloshinskii , J. Exp. Theor. Phys. 5, pp1259 (2007),; T. Moriya , Phys. Rev. 120 , pp91 (1960).
[4] G. Chen, et al., Ap. Phys. Lett. 106, 062402 (2015)