本實驗中以MBE成長Bi2Se3於Al203（0001）基板上，並利用RHEED、AFM和XRD的表面和結構量測，確認樣品的品質是非常良好且表面平坦的單晶薄膜，並在室溫下利用自旋幫浦（spin pumping）機制，在鎳鐵層和Bi2Se3接面的樣品上，提供外加磁場和微波是使鐵磁層發生鐵磁共振，使鎳鐵層向Bi2Se3層傳遞一自旋角動量，即為自旋流，此自旋流可以在Bi2Se3層引發反轉自旋霍爾效應（Inverse spin Hall effect, ISHE），是為自旋幫浦。由此量測在以自旋幫浦在Bi2Se3產生的電壓，再利用文獻中的電壓來源於對稱和反對稱的訊號，擬合出對稱的電壓訊號（Vsym），並改變頻率、功率或磁場強度以確認量測到對稱訊號的電壓（Vsym）確實是為反轉自旋霍爾效應所產生的電壓（VISHE）。並且改變Bi2Se3薄膜的厚度以探討厚度對Bi2Se3與ISHE之間的特性和其物理意義。

Bi2Se3 is one of the promising “second generation” topological insulator (TI) materials, which have both helical spin polarization and strong spin-orbit coupling. In this work, high quality Bi2Se3 thin films were grown on c-plane sapphire (Al2O3) substrates by molecular beam epitaxy (MBE). The central part of the Bi2Te3 layer was covered with a permalloy (Ni80Fe20) layer by IBS with a shadow mask. Through the spin-electricity conversion, and the spin injection into the topological insulator Bi2Se3 thin film can be observed at room temperature (RT) by a spin pumping method. The DC voltage VISHE were obtained and heating effect signals are hard to observed in a Py/Bi2Se3 bilayer system at RT. Our measurements reveal that Py/Bi2Se3 bilayer system could be used as spin-based devices or spintronic devices.

[1] M. I. Dyakonov and V. I. Perel, "Possibility of orientating electron spins with current", Sov Phys JETP Lett 13, 467 (1971)
[2] M.I. Dyakonov and V.I. Perel, "Current-induced spin orientation of electrons in semiconductors", Phys. Lett. A 35, 459 (1971)
[3] J.E. Hirsch, "Spin Hall Effect", Phys. Rev. Lett. 83, 1834 (1999)
[4] E. Saitoh, M. Ueda, and H. Miyajima, “Conversion of spin current into charge current at room temperature: Inverse spin-Hall effect” Appl. Phys. Lett. 88, 182509 (2006)
[5] Kazuya Ando, "Dynamical generation of spin currents”, Semicond. Sci. Technol. 29, 043002 (2014)
[6] O. Mosendz, " Detection and quantification of inverse spin Hall effect from spin pumping in permalloy/normalmetal bilayers”, PHYSICAL REVIEW B 82, 214403 (2010)
[7] A. Azevedo, “Spin pumping and anisotropic magnetoresistance voltages in magnetic bilayers:Theory and experiment” PHYSICAL REVIEW B 83, 144402 (2011)
[8] H. Nakayama, “Geometry dependence on inverse spin Hall effect induced by spin pumping in Ni81Fe19/Pt films” PHYSICAL REVIEW B 85, 144408 (2012)
[9] O. Mosendz, “Quantifying Spin Hall Angles from Spin Pumping: Experiments and Theory”, PRL 104, 046601 (2010)
[10] Hsiu-Cheng Chang and Chun-Hua Chen, “Self-assembled bismuth telluride films with well-aligned zero- to three-dimensional nanoblocks for thermoelectric applications” CrystEngComm 13, 5956 (2011)
[11]維基百科，取自於”http://en.wikipedia.org/wiki/Landau%E2%80%93Lifshitz%E2%80%93Gilbert_equation”
[12] General Area Detector Diffraction System (GADDS) user manual, USA: Technical Publications Department Bruker AXS Inc.
[13] Y. K. Kato, “Science 10 December 2004: Vol. 306 no. 5703 pp. 1910-1913“, Science 306, 1910 (2004)
[14] Y Iwata, “In situ refection high-energy electron di!raction (RHEED)
observation of Bi2Te3/Sb2Te3 multilayer film growth” Journal of Crystal Growth 203, 125-130 (1999)
[15]陳威寧 碩士論文 國立成功大學 (2012)
[16] CHENG P. WEN, “Coplanar Waveguide: A Surface Strip Transmission Line Suitable for Nonreciprocal Gyromagnetic Device Applications”, IEEE 12, 17 (1969)
[17] Yi Zhang, “Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit”, Nature Physics 6, 584–588 (2010)
[18] Haijun Zhang, “Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface”, Nature Physics 5, 438 - 442 (2009)
[19] J. E. Moore, “Topological invariants of time-reversal-invariant band structures”, Phys. Rev. B 75, 121306 (2007)
[20] B. Andrei Bernevig, “Quantum spin hall effect and topological phase transition in HgTe Quantum wells”, Science 314, 1757 (2006)
[21] Liang Fu, “Topological Insulators in Three Dimensions”, Phys. Rev. Lett. 98, 106803 (2007)
[22] M. Zahid Hasan, “Three-Dimensional Topological Insulators”, Annu. Rev. Condens. Matter Phys.2:55–78 (2011)