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Room temperature spin diffusion in (110) GaAs/AlGaAs quantum wells.

Hu C, Ye H, Wang G, Tian H, Wang W, Wang W, Liu B, Marie X - Nanoscale Res Lett (2011)

Bottom Line: Transient spin grating experiments are used to investigate the electron spin diffusion in intrinsic (110) GaAs/AlGaAs multiple quantum well at room temperature.The measured spin diffusion length of optically excited electrons is about 4 μm at low spin density.Increasing the carrier density yields both a decrease of the spin relaxation time and the spin diffusion coefficient Ds.

View Article: PubMed Central - HTML - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P,O, Box 603, Beijing 100190, PR China. blliu@iphy.ac.cn.

ABSTRACT
Transient spin grating experiments are used to investigate the electron spin diffusion in intrinsic (110) GaAs/AlGaAs multiple quantum well at room temperature. The measured spin diffusion length of optically excited electrons is about 4 μm at low spin density. Increasing the carrier density yields both a decrease of the spin relaxation time and the spin diffusion coefficient Ds.

No MeSH data available.


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Spin diffusion coefficient and spin dynamics for two different powers. (a) Decay rate of spin grating as a function of q2 for two excitation powers: 2 and 18mW. (b) Kerr rotation dynamics obtained from homogenous spin excitation.
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Figure 2: Spin diffusion coefficient and spin dynamics for two different powers. (a) Decay rate of spin grating as a function of q2 for two excitation powers: 2 and 18mW. (b) Kerr rotation dynamics obtained from homogenous spin excitation.

Mentions: where Ds is the spin diffusion coefficient, q is the spin grating wave vector, and is the spin lifetime which includes the effect of both the electron spin relaxation time τs and the recombination time τr, as expressed by . To separate the effects of spin diffusion and spin relaxation, the grating decay rate is measured as a function of the grating wave vector q by changing the phase mask with different periods (d = 5, 6, 7, and 8 μm) and/or the second spherical mirror with different focus lengths (f2 = 15.2 and 30.4 cm). Figure 2a shows the grating decay rate as a function of q2 for two excitation powers. Each set of data points can be fitted linearly, yielding the spin diffusion coefficient Ds. At low excitation power of 2 mW, which corresponds to an optical intensity of 30W/cm2, we find Ds = ~102 cm2/s. This value is in good agreement with the values obtained by other groups in (110)-grown GaAs/AlGaAs QWs at RT [8,20]. It is also very close to the spin diffusion coefficient Ds measured in (100)-grown GaAs/AlGaAs QWs at RT [9,10]. This result suggests that the spin diffusion coefficient Ds does not depend critically on the spin-orbit coupling, which depends on the crystalline direction of the sample. Nevertheless, as shown in Figure 2a, it is very sensitive to the carrier density.


Room temperature spin diffusion in (110) GaAs/AlGaAs quantum wells.

Hu C, Ye H, Wang G, Tian H, Wang W, Wang W, Liu B, Marie X - Nanoscale Res Lett (2011)

Spin diffusion coefficient and spin dynamics for two different powers. (a) Decay rate of spin grating as a function of q2 for two excitation powers: 2 and 18mW. (b) Kerr rotation dynamics obtained from homogenous spin excitation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211199&req=5

Figure 2: Spin diffusion coefficient and spin dynamics for two different powers. (a) Decay rate of spin grating as a function of q2 for two excitation powers: 2 and 18mW. (b) Kerr rotation dynamics obtained from homogenous spin excitation.
Mentions: where Ds is the spin diffusion coefficient, q is the spin grating wave vector, and is the spin lifetime which includes the effect of both the electron spin relaxation time τs and the recombination time τr, as expressed by . To separate the effects of spin diffusion and spin relaxation, the grating decay rate is measured as a function of the grating wave vector q by changing the phase mask with different periods (d = 5, 6, 7, and 8 μm) and/or the second spherical mirror with different focus lengths (f2 = 15.2 and 30.4 cm). Figure 2a shows the grating decay rate as a function of q2 for two excitation powers. Each set of data points can be fitted linearly, yielding the spin diffusion coefficient Ds. At low excitation power of 2 mW, which corresponds to an optical intensity of 30W/cm2, we find Ds = ~102 cm2/s. This value is in good agreement with the values obtained by other groups in (110)-grown GaAs/AlGaAs QWs at RT [8,20]. It is also very close to the spin diffusion coefficient Ds measured in (100)-grown GaAs/AlGaAs QWs at RT [9,10]. This result suggests that the spin diffusion coefficient Ds does not depend critically on the spin-orbit coupling, which depends on the crystalline direction of the sample. Nevertheless, as shown in Figure 2a, it is very sensitive to the carrier density.

Bottom Line: Transient spin grating experiments are used to investigate the electron spin diffusion in intrinsic (110) GaAs/AlGaAs multiple quantum well at room temperature.The measured spin diffusion length of optically excited electrons is about 4 μm at low spin density.Increasing the carrier density yields both a decrease of the spin relaxation time and the spin diffusion coefficient Ds.

View Article: PubMed Central - HTML - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P,O, Box 603, Beijing 100190, PR China. blliu@iphy.ac.cn.

ABSTRACT
Transient spin grating experiments are used to investigate the electron spin diffusion in intrinsic (110) GaAs/AlGaAs multiple quantum well at room temperature. The measured spin diffusion length of optically excited electrons is about 4 μm at low spin density. Increasing the carrier density yields both a decrease of the spin relaxation time and the spin diffusion coefficient Ds.

No MeSH data available.


Related in: MedlinePlus