自旋幫浦引致半導體氧化鋅之逆自旋霍爾效應

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Research Express@NCKU - Articles Digest

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Research Express@NCKU Volume 28 Issue 9 - March 27, 2015

[ http://research.ncku.edu.tw/re/articles/e/20150327/1.html ]

Inverse spin Hall effect induced by spin pumping into

semiconducting ZnO

Jung-Chuan Lee

1

, Leng-Wei Huang

2

, Dung-Shing Hung

1,3

, Tung-Han Chiang

4

, J. C. A.

Huang

4,5,*

, Jun-Zhi Liang

6

, Shang-Fan Lee

1,2

1_{Institute of Physics, Academia Sinica, Taipei 11529, Taiwan}

2_{Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan} 3_{Department of Information and Telecommunications Engineering, Ming Chuan University, Taipei} 111, Taiwan

4_{Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan}

5_{Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101,} Taiwan

6_{Department of Physics, Fu Jen Catholic University, Taipei 242, Taiwan} [email protected]

Applied Physics Letters 104, 052401 (2014).

T

he generation, manipulation, and detection of the spin current are very important and necessary for spintronics devices. The spin Hall effect (SHE) refers to the phenomenon that the spin-up and spin-down transport electrons accumulate transversely on opposite sides of a nonmagnetic conductor due to the spin-orbit coupling (SOC) that occurs without an external magnetic field. Consequently, the SHE can provide a simple physical mechanism to generate the transverse spin current by using the longitudinal charge current [1,2]. However, it is very difficult to observe the

spin Hall effect in semiconductors, especially for ones with weak SOC. Group II-VI semiconductor material Zinc Oxide (ZnO) has attracted a lot of attention lately for its prospects in optoelectronics applications owing to its direct wide band gap and large exciton binding energy[3]. In addition, it has a small SOC, implying a large spin coherence length. Therefore, ZnO is also a promising candidate for combining optoelectronics and spintronics applications[4,5]. We have successfully injected the spin current into semiconductor ZnO thin films with weak SOC by utilizing the spin pumping method and observed the Inverse spin Hall effect (ISHE).

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FIG. 1. Schematic illustration of the ZnO/Ni₈₀Fe₂₀ films. H represents an external magnetic field, angle θ is between the field and microwave propagation direction, Y axis, can be varied.

FIG. 2. (a) Magnetic field H dependence of the electromotive force V of ZnO/Ni₈₀Fe₂₀ thin film under 50 mW

microwave excitation, where θ are 0˚ and 180˚. The solid lines show the fitting results using the Lorentz function. V_ISHE is estimated as the peak height of the resonance shape in the V spectra. (b) Shows the in-plane angle θ

dependence of the electromotive force V for ZnO/Ni₈₀Fe₂₀. The hollow symbols are the experimental data, and

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FIG. 3. FMR linewith as a function of microwave frequency for ZnO/Ni₈₀Fe₂₀. The inset shows microwave power

P_MW dependence of V_ISHE for the ZnO/Ni₈₀Fe₂₀ bilayer at θ = 0˚ and 180˚.

Reference:

1. M. I. Dyakonov and V. I. Perel, Phys. Lett. A 35, 459 (1971). 2. J. E. Hirsch, Phys. Rev. Lett. 83, 1834 (1999).

3. Ü. Özgür, Ya. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Doğan, V. Avrutin, S.-J. Cho, and H. Morkoç, J, Appl. Phys. 98, 041301 (2005).

4. W. M. Chen, A. Buyanova, A. Murayama, T. Furuta, Y. Oka, D. P. Norton, S. J. Pearton, A. Osinsky, and J. W. Dong, Appl. Phys. Lett. 92. 092102 (2008).

5. M. Althammer, E.-M. K.-M., S. T. B. Goennenwein, M. Opel, and R. Gross, Appl. Phys. Lett. 101, 082404 (2012).