| Project/Area Number |
09305001
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | University of Tsukuba |
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Principal Investigator |
TAKITA Koki Institute of Materials Sciences University of Tsukuba, Professor, 物質工学系, 教授 (00011213)
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| Co-Investigator(Kenkyū-buntansha) |
KURODA Shinji Institute of Materials Sciences University of Tsukuba, Lecturer, 物質工学系, 講師 (40221949)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥39,200,000 (Direct Cost: ¥39,200,000)
Fiscal Year 1999: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1998: ¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1997: ¥27,400,000 (Direct Cost: ¥27,400,000)
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| Keywords | diluted magnetic semiconductors / type II superconductors / quantum dots / flux line lattice / gigantic Zeeman splitting / van der Waals epitaxy / ファンデルワールスエピタキシ- |
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| Research Abstract |
In the mixed state of type-II superconductors, the spatial modulation of magnetic flux density takes place on the surface due to the regular distribution of magnetic flux. In the hybrid structure in which diluted magnetic semiconductors (DMS) are attached on the surface of type-II superconductors, it is expected that the effective band-gap of DMS is modulated by the above field modulation and quantum confinement in the zero-dimension is realized by the flux line lattice in the superconductors. In the present research project, we have tried to fabricate the hybrid structure of Cd_<1-x> Mn_xTe and NbSe_2 by MBE growth technique.
NbSe_2 is of the layered crystal structure, in which the coupling between the layers is due to van der Waals force. The epitaxial growth of the zinc-blende crystal structure, CdTe or Cd_<1-x> Mn_xTe in the present case, on the layered crystal belongs to the category of quasi-van der Waals epitaxy ; that is, the surface of the layered crystal is free of dangling bo
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nds, onto which it is expected the zincblende crystal is grown without interface strain even with a mismatch of 33%. In in situ observation of the RHEED image, the streak pattern of NbSe_2 was transformed into that of CdTe(111) surface continuously, which showed that the two-dimensional growth was achieved at the very initial stage of the growth. Photoluminescence (PL) measurements of the grown crystals showed a good optical quality with a narrow linewidth of the exciton emission.
In order to examine the effect of the magnetic field modulation due to the magnetic flux in NbSe_2, we have performed magneto-PL measurements on Cd_<1-x>Mn_xTe films and Cd_<1-x>Mn_xTe/Cd_<1-y> Mn_yTe single quantum well (SQW) grown on NbSe_2. At low temperatures less than 4.2K, the linewidth of the excitonic emission showed anomalous behaviors ; that is, the linewidth first increased with magnetic fields, then took maximum, and decreased with the further increase of magnetic fields. This anomalous behavior could be understood as the effect of the field modulation due to the flux line lattice. Less
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