Geoffrey Beach

Affiliations

• Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

Title

Spin orbit torques and chiral spin textures in ultrathin magnetic films

Abstract

Spin-orbit coupling at interfaces in ultrathin magnetic films can give rise to chiral magnetic textures such as homochiral domain walls and magnetic skyrmions, as well as current-induced torques that can efficiently manipulate them [1-3]. This talk will describe interface-driven spin-orbit torques and Dzyaloshinskii-Moriya interactions (DMIs) in ultrathin ferromagnets adjacent to nonmagnetic heavy metals. We show that the DMI depends strongly on the heavy metal, differing by a factor of ~20 between Pt and Ta [2], and describe the influence of strong DMI on domain wall dynamics [1,2] and spin Hall effect switching [3]. We then present high-resolution x-ray microscopy and scanning probe imaging of chiral magnetic skyrmions and their dynamics in multilayer films that allow the relevant energy terms to be engineered [4]. Finally, we will describe how SOTs can be enhanced through interface engineering [5] and tuned by a gate voltage [6] by directly controlling the interfacial oxygen coordination at a ferromagnet/oxide interface [7].

References

• [1] S. Emori, et al., Nature Mater. 12, 611 (2013).
• [2] S. Emori, et al., Phys. Rev. B 90, 184427 (2014).
• [3] N. Perez, et al., Appl. Phys. Lett. 104, 092403 (2014).
• [4] S. Woo, et al., arXiv:1502.07376 (2015).
• [5] S. Woo, et al., Appl. Phys. Lett. 105, 212404 (2014).
• [6] S. Emori, et al., Appl. Phys. Lett. 105, 222401 (2014).
• [7] U. Bauer, et al., Nature Mater. 14, 174 (2015).