November 07, 2022
Minneapolis, United States
Interfacial potential gradient modulates Dzyaloshinskii Moriya interaction in Pt|Co|Metal multilayers
The actual mechanisms occurring at interfaces underlying the Dzyaloshinskii-Moriya interaction (i-DMI) remain largely an open question in nanomagnetism. In this study, we investigate the origin of the i-DMI, aiming at estimating how independent the DMI contributions of the two interfaces of a FM layer are and what their relative weight in the effective DMI amplitude is. The effective DMI is measured by the study of the asymmetric domain wall propagation in the presence of an in-plane magnetic field, in Pt|Co|M stacks. These measurements are completed by Brillouin light scattering (BLS) measurements. We then explore the correlation between the effective i-DMI and the properties of metal M, namely, its atomic number, electronegativity, and work function. A clear linear relationship is found between the i-DMI and the work function difference at the Co|M interface (ΔΦ) 1,2. We define Δφ = φM - φCo. This result is a strong evidence of the independent DMI contributions of the two interfaces for the chosen Co thickness (1 nm). These findings may guide the optimization of the magnetic properties of future spintronic devices.
This work has been supported by DARPA TEE program grant (MIPR HR-0011831554), ANR grant TOPSKY (ANR-17-CE24-0025), FLAG-ERA SographMEM (ANR-15-GRFL-0005), and the Horizon2020 Framework Program of the European Commission, under FET Proactive Grant Agreement No. 824123 (SKYTOP) and under Marie Sklodowska- FQ Curie Grant Agreement No. 754303 for supporting J.P.G together with the LABEX LANEF in Grenoble (ANR-10-LABX-0051). Univ. Paris-Saclay, CNRS INP, Sesame IMAGeSPIN project (nEX039175) and the LABEX NanoSaclay (ANR10 LABX0035, BLS@PSay and SPiCY projects) are acknowledged for the BLS equipment.
References 1 F. Ajejas et al., Phys. Rev. Mat., June 2022 2 Y.-K. Park et al., NPG Asia Mater. 10, 995 (2018)