Realizing high-quality interfaces in 2D material spin valves

Ting-Chun Huang^1*, Wen-Hua Wu¹, Meng-Ting Wu², Chiashain Chuang², Chi-Feng Pai³, Ya-Ping Hsieh⁴, Mario Hofmann¹

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Department of Electronic Engineering, Chung Yuan Christian University, Taoyuan, Taiwan
³Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan
⁴Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Ting-Chun Huang, email:timothy1207s@gmail.com

2D materials are considered enabling components in magnetic spin valves that could increase the performance and robustness of spintronic devices. However, experimental results have been below expectations due to challenges in achieving contamination-free interfaces between the 2D material barrier and its ferromagnetic contacts. We here demonstrate an approach to realize interfaces with unprecedented quality using a single-step fabrication approach. By simultaneously depositing asymmetric contacts on a suspended 2D material, the effect of oxidation and voiding can be avoided. Graphene-based spin valves show a strong interaction at the interface that leads to exceptional magnetoresistance values. This advance permits the characterization of the intrinsic spin properties at the Co/graphene interface and we establish the limitations of traditional Hanle-based spin-lifetime measurements. Finally, we investigate the differences in spin transport for multi-layer graphene-based spin valves. An increased spin-scattering is observed that limits the achievable performance and provides guidelines for the future integration of 2D materials in spintronic devices.

Keywords: Graphene, Spintronics, Magnetoresistance, Interface