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Considerable interest has been aroused in the study of the spin dynamics in semiconductors due to its potential applications in spintronics and quantum computation. In this paper, time-resolved circularly polarized pump-probe spectroscopy is used to study the carrier density dependences on the electron spin relaxation in approximately symmetrical and completely asymmetrical doping (110) GaAs/AlGaAs quantum wells. With the increase of the carrier density, the spin relaxation time first increases and then decrease obviously in both of the quantum wells, and the measured spin relaxation time of the approximately symmetrical doping quantum wells is always longer than that of the asymmetrical doping one. By analysis, we find that the spin relaxation is not dominated only by the Bir-Aronov-Pikus (BAP) mechanism in (110) GaAs quantum wells, that though the Dresselhaus spin-orbit coupling does not lead to any spin relaxation, the asymmetry of the doping position contributes to the asymmetry of potential energy structure, thus the built-in electric field which can induce the Rashba spin-orbit coupling to appear, and that the effective magnetic field induced by the Rashba spin-orbit coupling normal to the growth direction can lead to spin relaxation along the growth direction. Therefore, the Dyakonov-Perel (DP) mechanism plays an important role in asymmetrical doping (110) GaAs/AlGaAs quantum wells. In the approximately symmetrical and completely asymmetrical doping (110) GaAs/AlGaAs quantum wells, the DP mechanism dominates the spin relaxation at low carrier density, thus the spin relaxation time increases with carrier density increasing due to the strengthening of the electron-electron scattering and the decreasing of the momentum relaxation time. However, at high carrier density, BAP mechanism plays an important role, thus the spin relaxation time decreases obviously with carrier density increrasing, but the decay rates in both of the quantum wells are slower than that in the casethat only BAP mechanism dominates, because both the DP and BAP mechanism play an important role. The strength of the Rashba spin-orbit coupling depends on the symmetry of the quantum well. The DP mechanism in a completely asymmetrical doping quantum well is stronger than that in an approximately symmetrical doping quantum wells, thus the decay rate in a completely asymmetrical doping quantum wells is always slower than that in an approximately symmetrical doping quantum wells, and the spin relaxation time in a completely asymmetrical doping quantum wells is shorter than that in an approximately symmetrical doping quantum wells.
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Keywords:
- circularly polarized pump-probe spectroscopy /
- electron spin relaxation /
- doping symmetry /
- GaAs/AlGaAs quantum wells
[1] Zutic I, Fabian J, Das Sarma S 2004Rev. Mod. Phys. 76 323
[2] Loss D, DiVincenzo D P 1998Phys. Rev. A 57 120
[3] Zhang T T, Barate P, Nguyen C T, Balocchi A, Amand T, Renucci P, Carrere H, Urbaszek B, Marie X 2013Phys. Rev. B 87 041201
[4] Krishnamurthy S, van Schilfgaarde M, Newman N 2003Appl. Phys. Lett. 83 1761
[5] Teng L H, Zhang P, Lai T S, Wu M W 2008Europhys. Lett. 84 27006
[6] Lai T S, Teng L H, Jiao Z X, Xu H H, Lei L, Wen J H, Lin W Z 2007Appl. Phys. Lett. 91 062110
[7] Lai T S, Liu X D, Xu H H, Jiao Z X, Wen J H, Lin W Z 2006Appl. Phys. Lett. 88 192106
[8] Chen X X, Teng L H, Liu X D, Huang Q W, Wen J H, Lin W Z, Lai T S 2008Acta Phys. Sin. 57 3853(in Chinese)[陈小雪, 滕利华, 刘晓东, 黄绮雯, 文锦辉, 林位株, 赖天树2008 57 3853]
[9] Wu Y, Jiao Z X, Lei L, Wen J H, Lai T S, Lin W Z 2006Acta Phys. Sin. 55 2961(in Chinese)[吴羽, 焦中兴, 雷亮, 文锦辉, 赖天树, 林位株2006 55 2961]
[10] Wu M W, Jiang J H, Weng M Q 2010Phys. Reports 493 61
[11] Xia J B, Ge W K, Chang K 2008Semiconductor Spintronics (Beijing:Science Press) p216(in Chinese)[夏建白, 葛惟昆, 常凯2008半导体自旋电子学(北京:科学出版社)第216页]
[12] Ohno Y, Terauchi R, Adachi T, Matsukura F, Ohno H 1999Phys. Rev. Lett. 83 4196
[13] Eldridge P S, Lagoudakis P G, Henini M, Harley R T 2010Phys. Rev. B 81 033302
[14] Vlkl R, Griesbeck M, Tarasenko S A, Schuh D, Wegscheider W, Schller C, Korn T 2011Phys. Rev. B 83 241306
[15] Han L F, Zhu Y G, Zhang X H, Tian P H, Ni H Q, Niu Z C 2011Nanoscale Res. Lett. 6 84
[16] Xu H H, Jiao Z X, Liu X D, Lei L, Wen J H, Wang H, Lin W Z, Lai T S 2006Acta Phys. Sin. 55 2618(in Chinese)[徐海红, 焦中兴, 刘晓东, 雷亮, 文锦辉, 王惠, 林位株, 赖天树2006 55 2618]
[17] Teng L H, Mu L J, Wang X 2014Physica B 436 177
[18] Lai T S, Liu L N, Shou Q, Lei L, Lin W Z 2004Appl. Phys. Lett. 85 4040
[19] Teng L H, Chen K, Wen J H, Lin W Z, Lai T S 2009J. Phys. D:Appl. Phys. 42 135111
[20] Vlkl R, Schwemmer M, Griesbeck M, Tarasenko S A, Schuh D, Wegscheider W, Schller C, Korn T 2014Phys. Rev. B 89 075424
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[1] Zutic I, Fabian J, Das Sarma S 2004Rev. Mod. Phys. 76 323
[2] Loss D, DiVincenzo D P 1998Phys. Rev. A 57 120
[3] Zhang T T, Barate P, Nguyen C T, Balocchi A, Amand T, Renucci P, Carrere H, Urbaszek B, Marie X 2013Phys. Rev. B 87 041201
[4] Krishnamurthy S, van Schilfgaarde M, Newman N 2003Appl. Phys. Lett. 83 1761
[5] Teng L H, Zhang P, Lai T S, Wu M W 2008Europhys. Lett. 84 27006
[6] Lai T S, Teng L H, Jiao Z X, Xu H H, Lei L, Wen J H, Lin W Z 2007Appl. Phys. Lett. 91 062110
[7] Lai T S, Liu X D, Xu H H, Jiao Z X, Wen J H, Lin W Z 2006Appl. Phys. Lett. 88 192106
[8] Chen X X, Teng L H, Liu X D, Huang Q W, Wen J H, Lin W Z, Lai T S 2008Acta Phys. Sin. 57 3853(in Chinese)[陈小雪, 滕利华, 刘晓东, 黄绮雯, 文锦辉, 林位株, 赖天树2008 57 3853]
[9] Wu Y, Jiao Z X, Lei L, Wen J H, Lai T S, Lin W Z 2006Acta Phys. Sin. 55 2961(in Chinese)[吴羽, 焦中兴, 雷亮, 文锦辉, 赖天树, 林位株2006 55 2961]
[10] Wu M W, Jiang J H, Weng M Q 2010Phys. Reports 493 61
[11] Xia J B, Ge W K, Chang K 2008Semiconductor Spintronics (Beijing:Science Press) p216(in Chinese)[夏建白, 葛惟昆, 常凯2008半导体自旋电子学(北京:科学出版社)第216页]
[12] Ohno Y, Terauchi R, Adachi T, Matsukura F, Ohno H 1999Phys. Rev. Lett. 83 4196
[13] Eldridge P S, Lagoudakis P G, Henini M, Harley R T 2010Phys. Rev. B 81 033302
[14] Vlkl R, Griesbeck M, Tarasenko S A, Schuh D, Wegscheider W, Schller C, Korn T 2011Phys. Rev. B 83 241306
[15] Han L F, Zhu Y G, Zhang X H, Tian P H, Ni H Q, Niu Z C 2011Nanoscale Res. Lett. 6 84
[16] Xu H H, Jiao Z X, Liu X D, Lei L, Wen J H, Wang H, Lin W Z, Lai T S 2006Acta Phys. Sin. 55 2618(in Chinese)[徐海红, 焦中兴, 刘晓东, 雷亮, 文锦辉, 王惠, 林位株, 赖天树2006 55 2618]
[17] Teng L H, Mu L J, Wang X 2014Physica B 436 177
[18] Lai T S, Liu L N, Shou Q, Lei L, Lin W Z 2004Appl. Phys. Lett. 85 4040
[19] Teng L H, Chen K, Wen J H, Lin W Z, Lai T S 2009J. Phys. D:Appl. Phys. 42 135111
[20] Vlkl R, Schwemmer M, Griesbeck M, Tarasenko S A, Schuh D, Wegscheider W, Schller C, Korn T 2014Phys. Rev. B 89 075424
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