The dependence of the Composite Fermion effective mass on carrier density and Zeeman energy

Conference item

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 nu = 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 root 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.

Authors: Nicholas, R; Leadley, DR; Daly, MS; vanderBurgt, M; Gee, P

• Publication status: Published
• Journal: SEMICONDUCTOR SCIENCE AND TECHNOLOGY
• Volume: 11
• Issue: 11
• Pages: 1477-1481
• Publication date: 1996-11-01
• Event title: 9th International Winterschool on New Developments in Solid State Physics - Nanostructure Physics and Technology
• DOI: 10.1088/0268-1242/11/11S/003
• EISSN: 1361-6641
• ISSN: 0268-1242
• Keywords: SPIN; ELECTRON-SYSTEM; MAGNETOTRANSPORT; ENHANCEMENT; MAGNETIC-FIELDS; LANDAU-LEVEL; NU=1/2; QUANTUM HALL STATE