Quantitative Comparison between Field-like Spin-orbit Torque and Dzyaloshinskii-MoriyaInteraction

Abstract

Spin orbit torque (SOT) and Dzyaloshinskii-Moriya interaction (DMI) have opened a new generation of spintronics. Because SOTs are expected to be used to switch magnetic layer without external magnetic field which in turn, lead SOT-magnetic random-access memory (SOT-MRAM). And DMI can drive chiral spin textures which in turn, can lead skyrmion racetrack memory. These two quantities have been investigated extensively by many researchers forthe applicability explained above. Recently, some theoretical papers have indicated that there exists correlation between field-like SOT and DMI because they both have interfacial origin. Nevertheless, experimental evidence are still lacking in these days. Forthat reason, we prepare Ta(2.0 nm)/Pt(2.0 nm)/Co(t )/Pt(2.5 nm) film series and measure both field-like SOT and DMI. Here, t ranges from 0.4 nm to 0.9 nm. Samples are 0.1 nm-step made and all samples exhibit perpendicular magnetic anisotropy. We conduct second Hall harmonic technique to measure field-like SOT. To measure DMI, we used so-called effective depinning field method. Both field-like SOT effective field and DMI effective field are gradually increased as t decreased for entire measured regime. Similarly, the plot offield-like SOT efficiency and DMI strength X t product (which means interfacial contribution of DMI) with respect to t show the same trend. Therefore, we can conclude that field-like SOT and DMI are deeply related, which is attributed to their same origin from interfaces. The details will be shown on-site session.