Giant enhancement of spin–orbit torques with ultrathin high-<b> <i>κ</i> </b> dielectric insertion at the Pt/Co interface

Abstract

Achieving high spin–orbit torque (SOT) efficiency in heavy metal/ferromagnet (HM/FM) heterostructures is crucial for the development of energy-efficient spintronic devices. Among various factors, the HM/FM interface plays a pivotal role in determining the overall SOT efficiency. In this study, we examined the effect of introducing an ultrathin (∼0.2 nm) dusting layer of various dielectric oxides at the Pt/Co interface on the strength of SOT. Remarkably, the incorporation of TiOx—a high-κ dielectric—at the interface results in an 80%–100% enhancement in damping-like SOT. This significant improvement is attributed to the formation of high-dielectric TiOx islands at the interface, which act as additional scattering centers that facilitate spin current generation. Notably, this enhancement in SOT efficiency was achieved without adversely affecting the system's resistivity. Furthermore, we observed that the SOT efficiency scales with the dielectric constant of the interfacial oxide layer. These findings underscore the vital influence of interfacial dielectric properties in modulating SOT efficiency and present a promising strategy for advancing the performance of spintronic devices.