Effect of the oxide layer on the interfacial Dyzaloshinskii-Moriya interaction in perpendicularly magnetized Pt/Co/SmOx and Pt/Co/AlOx heterostructures
APPLIED SURFACE SCIENCE
Authors: Li, Dong; Ma, Rui; Cui, Baoshan; Yun, Jijun; Quan, Zhiyong; Zuo, Yalu; Xi, Li; Xu, Xiaohong
Abstract
The interfacial Dyzaloshinskii-Moriya interaction (DMI) plays a crucial role in stabilizing a chiral Neel-type magnetic domain wall in perpendicularly magnetized multilayers. In this work, we investigate the effect of oxide layers on interfacial DMI in ultrathin Pt/Co/SmOx and Pt/Co/AlOx stacks with the perpendicular magnetic anisotropy. The DMI effective field was characterized using the field driven domain wall creep and currentinduced hysteresis loop shift methods. The experimental results show that an enhanced interfacial DMI is obtained in Pt/Co/SmOx, stacks, which may be related to the oxidation degrees of the Co layer in view of the difference of Co/metallic oxide interfaces. Moreover, the X-ray photoelectron spectroscopy with the argon ion etching technique was used to further verify the weaker oxidation of the Co layer existed in Pt/Co/SmOx, than that in Pt/Co/AlOx in the same annealing process due to the smaller electronegativity of the Sm compared to the Al element. Our results provide a promising route to effectively manipulate the interfacial DMI in spin-orbittorque-based spintronic devices through the element electronegativity.
Photoemission study of the reaction of CO with Sm films on the Ru(001) surface
SURFACE REVIEW AND LETTERS
Authors: Rao, GR; Nozoye, H
Abstract
Photoemission spectroscopy (Ru 3d/C 1s and O 1s regions) has been used to investigate the formation of carbonate species on the Sm- and SmOx-covered Ru(001) surfaces at small exposures of CO. The results indicate that the reaction of similar to 1 L CO with disordered Sm layers on the Ru surface at 105 K produces surface carbonate and weakly bound CO2 via the Boudouard reaction (2CO(g) --> CO2,ad+C-ad). The latter species desorbs below 250 K, whereas the former is stable up to 500 K. The surface carbonate species is detected by the O 1s features as well as the C 1s feature developed in the Ru 3d region upon CO exposure. The CO reaction with the SmOx layer also leads to the formation of surface carbonate. The generation of carbonate on Sm and SmOx films seems to be related to the ionization of Sm atoms and the defects present in the partly oxidized Sm, respectively.