Self-Induced Spin Pumping in Cobalt Thin Films
Yi-Chien Weng1*, G. Y. Luo1, Jauyn Grace Lin1
1Center for condensed matter sciences, National Taiwan University, Taipei, Taiwan
* presenting author:Yi-Chien Weng, email:yichienweng@gmail.com
In spin pumping experiments, ferromagnetic resonance (FMR) technique is often applied in the bilayer structure of ferromagnetic material (FM) / normal metal (NM). In such structure, spin current is driven by FMR in FM layer and detected by inverse spin-Hall effect (ISHE) in NM layer. In this work, we study the self-induced ISHE in single layer structure, cobalt (Co) thin films. We prepared single layer thin films with by sputtering system with different thickness (t) where t = 5、7、10、13、15、20、25、30、40 nm. We obtained quantitatively charge current density (j_c)、effective magnetization (4πMeff) and damping constant (α) by analyzing FMR and ISHE data. Charge current and damping constant show a thickness dependent. Charge current has a maximal value of -0.28 μA and damping constant has a minimal value of 0.011 for Co(25 nm) thin film. Based on the theory of spin pumping, j_c is proportional to 1/α^2 , which is consistent with our experimental result.

Acknowledgement: This work is partly supported by Ministry of Science and Technology at Taiwan via the project number MOST-102-2112-M-002-012-MY3 (J.G.L.).


Keywords: spin pumping, Self-induced, inverse spin-Hall effect, cobalt thin film