Interfacial DMI in Fe/Pt thin films grown on different buffer layers

Abstract

We study the interfacial Dzyaloshinskii–Moriya interactions (i-DMI) of Fe/Pt bilayers grown on Si substrates with MgO, SiO2, or Ta each as a buffer layer on the basis of wave-vector-resolved Brillouin light scattering (BLS) measurement. The obtained i-DMI energy values for Fe/Pt on MgO, Ta, and SiO2 buffer layers are 0.359, 0.321, and 0.274 mJ/m2, respectively. The large i-DMI value observed in Fe/Pt system on the MgO buffer layer can be attributed to the good interfacial quality and the Rshaba effect at the MgO/Fe interface. Moreover, the MgO/Fe/Pt system, benefiting from better sample quality, exhibits a lower damping factor. Furthermore, layer-resolved first-principles calculations are carried out to gain a more in-depth understanding of the origin of the i-DMI in the Fe/Pt system. The results indicate that in the Fe(110)/Pt(111) system, the substantial DMI energy between Fe spins at the interface is related to a significant change in spin–orbit coupling (SOC) energy in the neighboring Pt layer. In contrast, for the MgO(002)/Fe(002) system, both the DMI and its related SOC energy are concentrated at the interfacial Fe layer. Our investigation will provide a valuable insight into the spintronic community in exploring novel devices with chirality dependence.