Particle-Hole Symmetry and the Fractional Quantum Hall Effect in the Lowest Landau Level

We report on detailed experimental studies of a high-quality heterojunction insulated-gate field-effect transistor (HIGFET) to probe the particle-hole symmetry of the fractional quantum Hall effect (FQHE) states about half-filling in the lowest Landau level. The HIGFET is specially designed to vary the density of a two-dimensional electronic system under constant magnetic fields. We find in our constant magnetic field, variable density measurements that the sequence of FQHE states at filling factors nu = 1/3, 2/5, 3/7. and its particle-hole conjugate states at filling factors 1-nu = 2/3, 3/5, 4/7. have a very similar energy gap. Moreover, a reflection symmetry can be established in the magnetoconductivities between the nu and 1-nu states about half-filling. Our results demonstrate that the FQHE states in the lowest Landau level are manifestly particle-hole symmetric.