| Project/Area Number |
01460037
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Gakushuin University |
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Principal Investigator |
KAWAJI Shinji Gakushuin University, Faculty of Science Professor, 理学部, 教授 (00080440)
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| Co-Investigator(Kenkyū-buntansha) |
WAKABAYASHI Junich Gakushuin University, Faculty of Science Research Associate, 理学部, 助手 (30129225)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1990: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | quantum Hall effect / quantized Hall resistance / fractional quantum Hall effect |
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| Research Abstract |
1. High precision measurements of quantized Hall resistance : Relative values of quantized Hall resistances R_H (4) and R_H (2) have been measured for a GaAs/AlGaAs heterostructures. R_H (4) (R_H (2)) was compared with a reference resistor R_R (4) (R_R (2)).The refe rence resistors were calibrated by comparing with a standard resistor of nominal 100 OMEGA whose value is denoted by R_<100>. Measurements of the ratios R_R (4)/R_<100> (2) and R_R (2)/R_<100> were carried out by the use of a self-balancing resistance ratio bridge with a cryogenic current comparator. Results show an appreciable difference between 4_XR_H (4) and 2_XR_H (4) -2_XR_H (2) = (0.038 <plus-minus> 0.018) ppm.
2. Localization of 2-dimensional systems under strong magnetic fields : : Diagonal and Hall conductivities of Si-MOSFETs have been measured at temperatures down to 50 mK and in magnetic fields up to 27 T. Temperature dependence of the peak value of electron concentration derivative of the Hall conductivity shows a plateau at temperatures lower than 0.2 K. Magnetic field dependence of the plateau value shows that the mobility edge is independent on the electron mobility.
3. Experiments related to the fractional quantum Hall effect : Diagonal and Hall resistances of a GaAs/AlGaAs heterostructure with electron mobility of 50m^2/Vs have been measured at temperatures down to 30 mK and in magnetic fields up to 27 T. Strong temperature dependence of the diagonal resistance was observed in a field where the filling factor of f Landau level is smaller than 1/5.
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