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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.

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Power-dependence spin diffusion coefficient and spin lifetime. (a) Spin diffusion coefficient Ds versus pump power, i.e., spin density; the blue line is a simple fit according to . (b) Pump power-dependent spin lifetime through Kerr rotation measurement with a fixed probe power of 0.2 mW.
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Figure 3: Power-dependence spin diffusion coefficient and spin lifetime. (a) Spin diffusion coefficient Ds versus pump power, i.e., spin density; the blue line is a simple fit according to . (b) Pump power-dependent spin lifetime through Kerr rotation measurement with a fixed probe power of 0.2 mW.

Mentions: Our spin diffusion coefficient results obtained at RT on (110) QWs contrast with the previous measurements of the carrier density dependence of the spin diffusion obtained at low temperature in n-doped bulk GaAs or (100) quantum wells [11,21]. In n-doped QWs, Carter et al. observed that Ds increases by increasing the density of the optically excited carriers. This increase of the electron spin diffusion coefficient was interpreted in terms of heating of the excess electrons due to relaxation of energetic optically excited carriers. Remarkably, in non-intentionally doped GaAs (110)-grown QWs, we observe at room temperature the opposite behavior. As displayed in Figure 3a, the spin diffusion coefficient Ds decreases abruptly for a pump power varying between 2 and 10 mW, and then remains almost coefficient up to 40 mW. In the same power range the spin lifetime (Figure 3b) has a different power dependence: it decreases monotonously as already observed by different groups, due to electron spin relaxation enhancement by the electron-hole exchange interaction [16]. Since the sample was undoped, we can equate the electron spin diffusion coefficient Ds to the electron charge diffusion coefficient De. The spin diffusion coefficient Ds can thus be written [22]:


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)

Power-dependence spin diffusion coefficient and spin lifetime. (a) Spin diffusion coefficient Ds versus pump power, i.e., spin density; the blue line is a simple fit according to . (b) Pump power-dependent spin lifetime through Kerr rotation measurement with a fixed probe power of 0.2 mW.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Power-dependence spin diffusion coefficient and spin lifetime. (a) Spin diffusion coefficient Ds versus pump power, i.e., spin density; the blue line is a simple fit according to . (b) Pump power-dependent spin lifetime through Kerr rotation measurement with a fixed probe power of 0.2 mW.
Mentions: Our spin diffusion coefficient results obtained at RT on (110) QWs contrast with the previous measurements of the carrier density dependence of the spin diffusion obtained at low temperature in n-doped bulk GaAs or (100) quantum wells [11,21]. In n-doped QWs, Carter et al. observed that Ds increases by increasing the density of the optically excited carriers. This increase of the electron spin diffusion coefficient was interpreted in terms of heating of the excess electrons due to relaxation of energetic optically excited carriers. Remarkably, in non-intentionally doped GaAs (110)-grown QWs, we observe at room temperature the opposite behavior. As displayed in Figure 3a, the spin diffusion coefficient Ds decreases abruptly for a pump power varying between 2 and 10 mW, and then remains almost coefficient up to 40 mW. In the same power range the spin lifetime (Figure 3b) has a different power dependence: it decreases monotonously as already observed by different groups, due to electron spin relaxation enhancement by the electron-hole exchange interaction [16]. Since the sample was undoped, we can equate the electron spin diffusion coefficient Ds to the electron charge diffusion coefficient De. The spin diffusion coefficient Ds can thus be written [22]:

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