Spin-current emission governed by nonlinear spin dynamics.

Takaharu Tashiro,Akiyo Nomura,Saki Matsuura,Henning Sirringhaus,Kazuya Ando,Shun Watanabe,Keehoon Kang

doi:10.1038/srep15158

Takaharu Tashiro, Akiyo Nomura + Show 5 more

Open Access

https://doi.org/10.1038/srep15158

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Journal: Scientific Reports	Publication Date: Oct 16, 2015
Citations: 11	License type: CC BY 4.0

Affiliation: Keio University, University of Cambridge

Abstract

Coupling between conduction electrons and localized magnetization is responsible for a variety of phenomena in spintronic devices. This coupling enables to generate spin currents from dynamical magnetization. Due to the nonlinearity of magnetization dynamics, the spin-current emission through the dynamical spin-exchange coupling offers a route for nonlinear generation of spin currents. Here, we demonstrate spin-current emission governed by nonlinear magnetization dynamics in a metal/magnetic insulator bilayer. The spin-current emission from the magnetic insulator is probed by the inverse spin Hall effect, which demonstrates nontrivial temperature and excitation power dependences of the voltage generation. The experimental results reveal that nonlinear magnetization dynamics and enhanced spin-current emission due to magnon scatterings are triggered by decreasing temperature. This result illustrates the crucial role of the nonlinear magnon interactions in the spin-current emission driven by dynamical magnetization, or nonequilibrium magnons, from magnetic insulators.

Highlights

(e) H dependence of dV(H)/dH for the Pt/Y3Fe5O12 film
The origin of the temperature-induced drastic change of the spin-conversion efficiency VISHE/Pabs shown in Fig. 2(a) is enhanced spin-current emission triggered by the three magnon splitting
The three-magnon splitting creates a pair of magnons with the opposite wavevectors and the frequency f0/2 from the uniform magnon with f0 [see Fig. 1(a)]

Summary

Results

Under the ferromagnetic resonance condition H = HR, dynamical magnetization in the Y3Fe5O12 layer emit a spin current js into the Pt layer, resulting in the voltage generation through the ISHE as shown in Fig. 1(d)[1,2]. The drastic change in VISHE/Pabs across 150 K at f0 = 4.0 GHz can be attributed to the change in the magnetization dynamics in the Y3Fe5O12 layer. By decreasing T, the microwave absorption intensity Pabs decreased clearly across T = 150 K as shown, suggesting the change of the magnetization dynamics in the Y3Fe5O12 layer across T = 150 K

Discussion

Nt Pabs

Additional Information