Source and Origin of the Interfacial Dzyaloshinskii-Moriya Interaction in a Heavy-Metal|magnetic-Insulator Bilayer

The interfacial Dzyaloshinskii-Moriya interaction (iDMI) was observed in the bilayer consisting of a heavy metal and a ferromagnetic insulator such as Pt vertical bar Tm3Fe5O12 (TIG), but the source and origin are still controversial. Here, we quantitatively investigate the iDMI strength in Pt vertical bar TIG by inserting a thin Y3Fe5O12 layer and/or a thin Cu layer between Pt and TIG. Our results suggest the iDMI contributed by both the Pt vertical bar TIG and the TIG vertical bar substrate interfaces. At the Pt vertical bar TIG interface, we find that Pt is essential for the strong iDMI. The disentangled iDMIs for Fe-Fe and Tm-Fe pairs are comparable, revealing that the Tm ions provide not only an additional Tm-Fe iDMI, but also the spin-orbit coupling to enhance the iDMI. At the TIG vertical bar substrate interface, the iDMI is attributed to the lattice-mismatch-induced deformation of the electron cloud for the ferromagnetic ions.

Physical Review B