Spin Pumping by Ferromagnetic Resonance Excited Magnon in Y3Fe5O12 Single Crystal
Y. S. Chen1*, S. Y. Huang2, J. G. Lin1
1Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
2Department of Physics, National Taiwan University, Taipei, Taiwan
* presenting author:You-Sheng Chen, email:youshengchen@ntu.edu.tw

Spin pumping phenomenon is intensively studied for the application of generating the pure spin current with high efficiency. With the excitation of ferromagnetic resonance (FMR) in a bi-layer system, spin torque is transferred from a ferromagnetic (FM) layer to a non-magnetic metal (NM) layer, activating the spin current in NM. Spin current reveals itself with an Inverse Spin Hall Effect (ISHE) induced DC voltage in the transverse direction of magnetization. Beside the coherent excitation, the FMR excited magnon also induce a similar spin pumping effect, which was observed in the bi-layer thin film of Yttrium iron garnet (YIG)/Pt.1 Previous studies concentrate on bi-layered thin films, allowing the semi-2D excitations of magnon. In this work, YIG single crystal plate with a thickness of 0.15 mm is studied. A Pt layer of 15 nm is deposited on the YIG plate to detect the ISHE signal. 9.8GHz of microwave is applied with a cavity of T102 mode. Out-of-plane angular dependent experiment of ISHE is performed. Our result shows that the transverse voltage generated by the excited magnons has contribution from the parametric pumping. However, the angular dependency of Voltage generated by each magnon mode is obviously different. In a 3-D system, we suggest that the out-of-plane direction of the magnon propagation has a significant influence on the ISHE response.

1 Y. Kajiwara et al., Nature 464, 262.(2010)

Keywords: spintronics, spin pumping, inverse spin hall effect, Yttrium iron garnet