Olson Samuel, Hood Kaleb, Zietz Otto, Jiao Jun
Department of Mechanical and Materials Engineering, Portland State University, Portland, OR 97201, USA.
Nanomaterials (Basel). 2025 Sep 4;15(17):1367. doi: 10.3390/nano15171367.
Graphene has promise as a channel connecting separate units of large-scale spintronic circuits owing to its outstanding theoretical spin transport properties. However, spin transport properties of experimental devices consistently fall short of theoretical estimates due to impacts from the substrate, electrodes, or defects in the graphene itself. In this study, we fabricate both traditional non-local spin valves (NLSVs) and novel hybrid drift-diffusion spin valves (HDDSVs) to explore the impact of charge current and AC spin injection efficiency on spin transport. HDDSVs feature channel branches that allow investigation of charge-based spin drift enhancement compared to diffusion-only configurations. We investigate the modulation of spin transport through hybrid drift-diffusion, observing a decrease in spin signal by 11% for channels with a 45° branch angle, and a 21% increase in spin signal for 135° branch angle channels. We then fabricate symmetrical 90° channel branch angle devices, which do not produce consistent spin transport modulation in drift diffusion mode. These findings highlight the role of carrier drift in enhancing or suppressing spin transport, depending on channel geometry and injection configuration. Overall, our work demonstrates a promising approach to optimizing spin transport in graphene devices by leveraging hybrid drift-diffusion effects without requiring additional DC current sources.
由于其出色的理论自旋输运特性，石墨烯有望成为连接大规模自旋电子电路中各个独立单元的通道。然而，由于受到衬底、电极或石墨烯本身缺陷的影响，实验装置的自旋输运特性始终低于理论估计值。在本研究中，我们制备了传统的非局域自旋阀（NLSV）和新型混合漂移扩散自旋阀（HDDSV），以探究充电电流和交流自旋注入效率对自旋输运的影响。HDDSV具有通道分支，与仅采用扩散的结构相比，能够研究基于电荷的自旋漂移增强情况。我们通过混合漂移扩散研究了自旋输运的调制情况，观察到对于具有45°分支角的通道，自旋信号降低了11%，而对于135°分支角的通道，自旋信号增加了21%。然后，我们制备了对称的90°通道分支角器件，这些器件在漂移扩散模式下不会产生一致的自旋输运调制。这些发现突出了载流子漂移在增强或抑制自旋输运中的作用，这取决于通道几何形状和注入配置。总体而言，我们的工作展示了一种有前景的方法，即通过利用混合漂移扩散效应来优化石墨烯器件中的自旋输运，而无需额外的直流电流源。
