Integral and Fractional Quantum Hall Effect
Project/Area Number  01460037 
Research Category 
GrantinAid for Scientific Research (B).

Research Field 
固体物性

Research Institution  Gakushuin University 
Principal Investigator 
KAWAJI Shinji Gakushuin University, Faculty of Science Professor, 理学部, 教授 (00080440)

CoInvestigator(Kenkyūbuntansha) 
WAKABAYASHI Junich Gakushuin University, Faculty of Science Research Associate, 理学部, 助手 (30129225)

Project Fiscal Year 
1989 – 1990

Project Status 
Completed(Fiscal Year 1990)

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)

Keywords  quantum Hall effect / quantized Hall resistance / fractional quantum Hall effect / 量子ホル効果 / 量子化ホル抵抗 / 分数量子ホル効果 
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 selfbalancing 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 <plusminus> 0.018) ppm. 2. Localization of 2dimensional systems under strong magnetic fields : : Diagonal and Hall conductivities of SiMOSFETs 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.

Report
(4results)
Research Output
(12results)