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正如人们所知, 可以通过电场或者设计非对称的半导体异质结构来调控体系的结构反演不对称性(SIA)和Rashba自旋劈裂. 本文研究了Al0.6Ga0.4N/GaN/Al0.3Ga0.7N/Al0.6Ga0.4N量子阱中第一子带的Rashba 系数和Rashba自旋劈裂随Al0.3Ga0.7N插入层(右阱)的厚度ws以及外加电场的变化关系, 其中GaN层(左阱)的厚度为40-ws . 发现随着ws的增加, 第一子带的Rashba系数和Rashba自旋劈裂首先增加, 然后在ws20 时它们迅速减小, 但是ws30 时Rashba自旋劈裂减小得更快, 因为此时kf也迅速减小. 阱层对Rashba系数的贡献最大, 界面的贡献次之且随ws变化不是太明显, 垒层的贡献相对比较小. 然后, 我们假ws=20 , 发现外加电场可以很大程度上调制该体系的Rashba系数和Rashba自旋劈裂, 当外加电场的方向同极化电场方向相同(相反)时, 它们随着外加电场的增加而增加(减小). 当外加电场从-1.5108 Vm-1到1.5108 V m-1变化时, Rashba系数随着外加电场的改变而近似线性变化, Rashba自旋劈裂先增加得很快, 然后近似线性增加, 最后缓慢增加. 研究结果表明可以通过改变GaN层和Al0.3Ga0.7N层的相对厚度以及外加电场来调节Al0.6Ga0.4N/GaN/Al0.3Ga0.7N/Al0.6Ga0.4N量子阱中的Rashba 系数和Rashba自旋劈裂, 这对于设计自旋电子学器件有些启示.
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关键词:
- Rashba自旋劈裂 /
- 自旋轨道耦合 /
- 自洽计算 /
- 极化效应
As is well known, the structure inversion asymmetry (SIA) and Rashba spin splitting of semiconductor heterostructure can be modulated by either electric field or engineering asymmetric heterostructure. In this paper, we calculate the Rashba coefficient and Rashba spin splitting for the first subband of Al0.6Ga0.4N/GaN/Al0.3Ga0.7N/Al0.6Ga0.4N QW each as a function of thickness (ws) of the inserted Al0.3Ga0.7N layer (right well) and external electric field. The thickness of GaN layer (left well) is 40-ws . With ws increasing, the Rashba coefficient and Rashba spin splitting for the first subband increase first, because the polarized electric field in the well region increases and the electrons shift towards the left heterointerfaces, and then decrease when ws20 since the electric field in the well region decreases, and the confined energy increases as effective well thickness decreases. But when ws30 , the Rashba spin splitting decreases more rapidly, since kF decreases rapidly. Contributions to the Rashba coefficient from the well is largest, lesser is the contribution from the interface, which varies slowly with ws, and the contribution from the barrier is relatively small. Then we assume ws=20 , and find that the external electric field can modulate the Rashba coefficient and Rashba spin splitting greatly because the contribution to the Rashba coefficient from the well changes rapidly with the external electric field, and the external electric field brings about additional potential and affects the spatial distribution of electrons, confined energy and Fermi level. When the direction of the external electric field is the same as (contrary to) the polarization electric field, the Rashba coefficient and Rashba spin splitting increase (decrease) with external electric field increasing. With the external electric field changing from -1.5108 V m-1 to 1.5108 V m-1, the Rashba coefficient approximately varies linearly, and the Rashba spin splitting first increases rapidly, then approximately increases linearly, and finally increases slowly. Because the value of kF increases rapidly first, then increases slowly. Results show that the Rashba coefficient and the Rashba spin splitting in the Al0.6Ga0.4N/GaN/Al0.3Ga0.7N/Al0.6Ga0.4N QW can be modulated by changing the relative thickness of GaN and Al0.3Ga0.7N layers and the external electric field, thereby giving guidance for designing the spintronic devices.-
Keywords:
- Rashba spin splitting /
- spin-orbit coupling /
- self-consistent calculation /
- polarized effect
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[24] Hao Y F, Chen Y H, Hao G D, Wang Z G 2009 Chin. Phys. Lett. 26 037103
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[29] Li M, Zhang R, Zhang Z, Yan W S, Liu B, Fu Deyi, Zhao C Z, Xie Z L, Xiu X Q, Zheng Y D 2010 Superlattices Microstruct. 47 522
[30] Koga T, Nitta J, Akazaki T, Takayanagi H 2002 Phys. Rev. Lett. 89 046801
[31] Schmult S, Manfra M J, Punnoose A, Sergent A M, Baldwin K W, Molnar R J 2006 Phys. Rev. B 74 033302
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[39] Wang X B, Zhao Z P, Feng Z H 2014 Acta Phys. Sin. 63 080202 (in Chinese) [王现彬, 赵正平, 冯志红 2014 物理学报 63 080202]
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[44] Bernardini F, Fiorentini V, Vanderbilt D 1997 Phys. Rev. B 56 R10024
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[1] Zutic I, Fabian J, Das S S 2004 Rev. Mod. Phys. 76 323
[2] Lo I, Gau M H, Tsai J K, Chen Y L, Chang Z J, Wang W T, Chiang J C, Aggerstam T, Lourdudoss S 2007 Phys. Rev. B 75 245307
[3] He X W, Shen B Tang Y Q, Tang N, Yin C M, Xu F J, Yang Z J, Zhang G Y, Chen Y H Tang C G, Wang Z G 2007 Appl. Phys. Lett. 91 071912
[4] Pfeffer P, Zawadzki W 1999 Phys. Rev. B 59 R5312
[5] Song H Z, Zhang P, Duan S Q, Zhao X G 2006 Chin. Phys. 15 3019
[6] Yan Y Z, Hu L B 2010 Chin. Phys. B. 19 047203
[7] Bernevig B A, Hughes T L, Zhang S C 2006 Science 314 1757
[8] Konig M, Wiedmann S, Bruene C, Roth A, Buhmann H, Molenkamp L W, Qi X L, Zhang S C 2007 Science 318 766
[9] Miao M S, Yan Q, van de Walle C G, Lou W K, Li L L, Chang K 2012 Phys. Rev. Lett. 109 186803
[10] Zhang D, Lou W K, Miao M S, Zhang S C, Chang K 2013 Phys. Rev. Lett. 111 156402
[11] Ganichev S D, Bel'kov V V, Golub L E, Ivchenko E L, Schneider P, Giglberger S, Eroms J, de Boeck J, Borghs G, Wegscheider W, Weiss D, Prettl W 2004 Phys. Rev. Lett. 92 256601
[12] Dresselhaus G 1955 Phys. Rev. 100 580
[13] Bychkov Y A, Rashba E I 1984 J. Phys. C 17 6039
[14] Bychkov Y A, Rashba E I 1984 JETP Lett. 39 78
[15] Wolf S A, Awschalom D D, Buhrman R A, Daughton J M, von Molnr S, Roukes M L, Chtchelkanova A Y, Treger D M 2001 Science 294 1488
[16] de Andrada e Silva E A, La Rocca G C, Bassani F 1994 Phys. Rev. B 50 8523
[17] de Andrada e Silva E A, La Rocca G C, Bassani F 1997 Phys. Rev. B 55 16293
[18] Winkler R 2003 Spin-Orbit Coupling Effects in Two-Dimensional Electron and Hole Systems (Berlin: Springer) pp77-86
[19] Yang W, Chang K 2006 Phys. Rev. B 73 113303
[20] Yang W, Chang K 2006 Phys. Rev. B 74 193314
[21] Hao Y F 2014 J. App. Phys. 115 244308
[22] Hao Y F 2015 J. App. Phys. 117 013911
[23] Hao Y F 2015 Phys. Lett. A 379 2853
[24] Hao Y F, Chen Y H, Hao G D, Wang Z G 2009 Chin. Phys. Lett. 26 037103
[25] Hao Y F, Chen Y H, Hao G D, Wang Z G 2009 Chin. Phys. Lett. 26 077104
[26] Yang P, L Y W, Wang X B 2015 Acta Phys. Sin. 64 197303 (in Chinese) [杨鹏, 吕燕伍, 王鑫波 2015 物理学报 64 197303]
[27] Litvinov V I 2003 Phys. Rev. B 68 155314
[28] Litvinov V I 2006 Appl. Phys. Lett. 89 222108
[29] Li M, Zhang R, Zhang Z, Yan W S, Liu B, Fu Deyi, Zhao C Z, Xie Z L, Xiu X Q, Zheng Y D 2010 Superlattices Microstruct. 47 522
[30] Koga T, Nitta J, Akazaki T, Takayanagi H 2002 Phys. Rev. Lett. 89 046801
[31] Schmult S, Manfra M J, Punnoose A, Sergent A M, Baldwin K W, Molnar R J 2006 Phys. Rev. B 74 033302
[32] Li M, L Y H, Yang B H, Zhao Z Y, Sun G, Miao D D, Zhao C Z 2011 Solid State Communi. 151 1958
[33] Li M 2013 Commun. Theor. Phys. 60 119
[34] Li M, Sun G, Fan L B 2012 Chin. Phys. Lett. 29 127104
[35] Li M, Zhang R, Liu B, Fu D Y, Zhao C Z, Xie Z L, Xiu X Q, Zheng Y D 2012 Acta Phys. Sin. 61 027103 (in Chinese) [李明, 张荣, 刘斌, 傅德彝, 赵传阵, 谢自力, 修向前, 郑有炓 2012 物理学报 61 027103]
[36] Calsaverini R S, Bernardes E, Carlos E J, Loss D 2008 Phys. Rev. B 78 155313
[37] Bernardes E, Schliemann J, Lee M, Carlos E J, Loss D 2007 Phys. Rev. Lett. 99 076603
[38] Tan I H, Snider G L, Chang L D Hu E L 1990 J. Appl. Phys. 68 4071
[39] Wang X B, Zhao Z P, Feng Z H 2014 Acta Phys. Sin. 63 080202 (in Chinese) [王现彬, 赵正平, 冯志红 2014 物理学报 63 080202]
[40] Ambacher O, Foutz B, Smart J Shealy J R, Weimann N G, Chu K, Murphy M Sierakowski A J, Schaff W J, Eastman L F, Dimitrov R, Mitchell A, Stutzmann M 2000 J. Appl. Phys. 87 334
[41] Ambacher O 1999 J. Appl. Phys 85 3222
[42] Kumagai M, Chuang S L, Ando H 1998 Phys. Rev. B 57 15303
[43] Suzuki M, Uenoyama T, Yanase A 1995 Phys. Rev. B 52 8132
[44] Bernardini F, Fiorentini V, Vanderbilt D 1997 Phys. Rev. B 56 R10024
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