Dzyaloshinskii-Moriya interaction at disordered interfaces from ab initio theory: Robustness against intermixing and tunability through dusting

Abstract

The Dzyaloshinskii-Moriya interaction (DMI), which is essential for the stabilization of topologically nontrivial chiral magnetic textures such as skyrmions, is particularly strong in heterostructures of ultra-thin magnetic materials and heavy elements. We explore by density-functional theory calculations the possibility to modify the magnetic properties at Co/Pt interfaces with chemical disorder. In these systems, we find a particular robustness of the DMI against intermixing. Upon dusting the interface with a third element (all 4d transition metals and B, Cu, Au and Bi), a strong reduction of the DMI is predicted. This opens up possibilities to tune the DMI through the degrees of intermixing and dusting.

Electric dipole moment as descriptor for interfacial Dzyaloshinskii-Moriya interaction

“…Since our values do not appear unreasonably high when compared to the DMI of a single Co/Pt interface with ultrathin Co layers (D s = 1.7 pJ/m) [58], we conjecture that the major difference arises from the different layer thicknesses and the related differences in the lattice strain. Additional factors responsible for the difference include our focus on atomically sharp trilayers, while in experimentally produced multilayers the vertical texture will certainly differ, e.g., due to slight intermixing effects at the interfaces [54] or a different stacking sequence. Another reason is that we have treated periodic multilayers where the non-magnetic spacer layer hybridizes with both Co and Pt layers, but in Ref.…”

“…Remarkably, this contribution changes drastically as the chemical type of the third layer is varied and, in effect, determines the overall trend of the DMI of the entire stack. This is surprising because it is commonly believed that the DMI at the Co/Pt interface can merely be changed by external means, e.g., by controlling the interface quality [53,54]. In contrast, the Co layer and third layer Z only contribute little to the DMI.…”

Comparison of first-principles methods to extract magnetic parameters in ultrathin films: Co/Pt(111)

“…Several recent studies focus on Co/Pt based systems 13,14 and explore the possibility to tune the material parameters, e.g. through additional buffer layers [15][16][17] , alloying 18,19 or dusting 20 with a third chemical element.…”

Enhancing domain wall velocity through interface intermixing in W-CoFeB-MgO films with perpendicular anisotropy

“…Such an important role of magnetic inhomogeneities in the current-induced motion of skyrmions has been revealed in recent studies, [7][8][9] taking into account a distribution of magnetic properties in a granular magnetic media where the grain size is comparable to the skyrmion diameter. One important source of disorder is related to the atomic-scale properties of the interface where roughness or interface intermixing 10,11 can not only induce a spatial distribution of interface anisotropy but also interfacial DMI. Recently, Zimmermann et al 10 employed ab initio calculations to study the effect of intermixing on DMI at Co/Pt interfaces, finding that the DMI dropped by about 20% and remained constant for a broad range of degrees of intermixing.…”

“…One important source of disorder is related to the atomic-scale properties of the interface where roughness or interface intermixing 10,11 can not only induce a spatial distribution of interface anisotropy but also interfacial DMI. Recently, Zimmermann et al 10 employed ab initio calculations to study the effect of intermixing on DMI at Co/Pt interfaces, finding that the DMI dropped by about 20% and remained constant for a broad range of degrees of intermixing. In another study, 12 ab initio calculations show that a 25% interfacial mixing at the Co/Pt interface reduced the total DMI value by half.…”