Spin orbit torques and chiral spin textures in ultrathin magnetic films (Presentation Recording)

Abstract

Spin orbit coupling at interfaces can give rise to chiral magnetic textures such as homochiral domain walls and skyrmions, as well as current-induced torques that can effectively manipulate them [1-3]. This talk will describe interface-driven spin-orbit torques and Dzyaloshinskii-Moriya interactions (DMIs) in ultrathin metallic 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 [4], and describe the influence of strong DMI on domain wall dynamics and spin Hall effect switching [5]. We present high-resolution magnetic force microscopy imaging of static magnetic textures that directly reveal the role of DMI and allow its strength to be quantified. Finally, we will describe how SOTs can be enhanced through interface engineering [6] and tuned by a gate voltage [7] by directly controlling the interfacial oxygen coordination at a ferromagnet/oxide interface [8]. [1] A. Thiaville, et al., Europhys. Lett. 100, 57002 (2012). [2] S. Emori, et al., Nature Mater. 12, 611 (2013). [3] J. Sampaio, V. Cros, S. Rohart, A. Thiaville, and A. Fert, Nature Nano. 8, 839 (2013). [4] S. Emori, et al., Phys. Rev. B 90, 184427 (2014). [5] N. Perez, et al., Appl. Phys. Lett. 104, 092403 (2014). [6] S. Woo, et al., Appl. Phys. Lett. 105, 212404 (2014). [7] S. Emori, et al., Appl. Phys. Lett. 105, 222401 (2014). [8] U. Bauer, et al., Nature Mater. 14, 174 (2015).