2001 Fiscal Year Final Research Report Summary
Imaging Spectroscopy of Exciton Spin Diffusion and Relaxation in Quantum Structure Semiconductors
| Project/Area Number |
12640320
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Hokkaido University |
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Principal Investigator |
ADACHI Satoru Hokkaido Univ., Grad. School of Eng., Associate Prof., 大学院・工学研究科, 助教授 (10221722)
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| Project Period (FY) |
2000 – 2001
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| Keywords | imaging / spin diffusion / spin relaxation / quantum structure / semiconductors |
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| Research Abstract |
In recent years, people have much interest on "spin electronics" such as spin transistors, where electronic spin plays more important role than its charge in semiconductors. Then knowledge of the spin relaxation and spin diffusion is one of keys for success. Nevertheless those physical mechanisms in quantum structures are not well known. Under this background, We studied the diffusion and relaxation of exciton spin in quantum well structures. For this purpose, we utilized the four-wave-mixing spectroscopy with spin grating. Two pump pulses generated the exciton density grating near the sample surface in the co-linear polarizations. For the cross-linear polarizations, the pump pulses cannot interfere and therefore uniform exciton density is created. But the mixture of up-spin and down-spin of exciton changes according to the spatial position and thus the spin grating can be created. The pitch of both density and spin gratings can adjust by the crossing angle between the pump pulses. The time-delayed probe pulse diffracted from those gratings gives the decay rate of the gratings that includes the information about the relaxation and diffusion of the spin and density according to the character of the created grating. So, we could measure the spin relaxation ; spin diffusion constant, recombination and density diffusion constant in the same system. In the result, we obtained that spin diffusion rate is 3.5-times larger than density diffusion. This result is for the first time under my knowledge.
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Research Products
(24 results)
