Abstract
In this study, we integrated bilayer structure of covered Pt on nickel zinc ferrite (NZFO) and CoFe/Pt/NZFO tri-layer structure by pulsed laser deposition system for a spin Hall magnetoresistance (SMR) study. In the bilayer structure, the angular-dependent magnetoresistance (MR) results indicate that Pt/NZFO has a well-defined SMR behavior. Moreover, the spin Hall angle and the spin diffusion length, which were 0.0648 and 1.31 nm, respectively, can be fitted by changing the Pt thickness in the longitudinal SMR function. Particularly, the MR ratio of the bilayer structure (Pt/NZFO) has the highest changing ratio (about 0.135%), compared to the prototype structure Pt/Y3Fe5O12 (YIG) because the NZFO has higher magnetization. Meanwhile, the tri-layer samples (CoFe/Pt/NZFO) indicate that the MR behavior is related with CoFe thickness as revealed in angular-dependent MR measurement. Additionally, comparison between the tri-layer structure with Pt/NZFO and CoFe/Pt bilayer systems suggests that the SMR ratio can be enhanced by more than 70%, indicating that additional spin current should be injected into Pt layer.
Highlights
Spin-orbit coupling (SOC)[1,2] is one of the most important phenomena in condensed matter physics, providing a mechanism to couple charge and spin of electrons, and bring several fields such like quantum spin Hall effect[3,4,5] and Topological insulators[6,7,8,9]
The main studies of the spin Hall magnetoresistance (SMR) behavior focus on the bilayer structure, in the ferromagnetic insulators (FMIs)/heavy metal (HM) structure, while the SMR behavior itself is generated from the interface of the ferromagnetic material (FM) layer and HM
The patterns indicate that the NZFO and Pt growth on NZFO have smooth and ideal surface condition, which is confirmed by the atomic force microscopy (AFM) result, and the surface roughness is 0.4 nm and 0.2 nm, as shown in
Summary
Compared to NZFO in-plane hysteresis loop, as shown, the coercive field of NZFO matched with the observed MR This suggests that the MR signal of the bilayer samples resulted from the interaction between NZFO and Pt. On the other hand, angular-dependent MR measurement can help identify the MR mechanism that results from SMR or anisotropic magnetoresistance (AMR). The difference between the SMR and the AMR behaviors was revealed in angular-dependent MR results. The angular-dependent MR results revealed that the SMR behavior clearly dominated in the Pt/NZFO bilayer structure.
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