| The dependence of the Composite Fermion effective mass on carrier density and Zeeman energy (2008) | |||||||||||||
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| Abstract. Measurements of the temperature-dependent resistivity of high-mobility GaAs/GaAlAs heterojunctions are used to measure the effective mass of Composite Fermions (CF). The CF effective mass is found to increase approximately linearly with the effective field B ∗ up to effective fields of 14 T. Data from all fractions around ν =1/2 are unified by the single parameter B ∗ for samples studied over a wide range of temperature. The energy gap is found to increase as √ B ∗ at high fields. Hydrostatic pressure is used to reduce the value of the electron g-factor, and this is shown to have a large effect on the relative strengths of different fractions. By 13.4 kbar, where the Zeeman energy is only 1/4 of its value at 0 bar, fractions with odd numerators are found to be strongly suppressed, and new features with even numerators appear. The energy gaps measured for 5/3 as a function of carrier density and pressure are consistent with a g-factor equal to the bulk value enhanced by a factor of two due to exchange interactions. The fractional quantum Hall effect has been known for many years [1, 2], but our picture of the phenomenon is | |||||||||||||
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