Novel composite-fermion phases: Crystals, stripes, and higher generations

Residual interactions between composite fermions, the quasi-particles responsible for the fractional quantum Hall effect, may be neglected at the Landau-level filling factors $\nu=p/(2sp+1)$, at which most fractional quantum Hall states are observed. However, they become relevant at fillings in between states of this series. We have derived the form of the interaction potential of composite fermions within a recently developed Hamiltonian formalism, and we show how these residual interaction may give rise to novel phases, such as crystals and stripes of composite fermions, as well as higher-generation states. The latter may be responsible for a recently observed fractional quantum Hall effect at $\nu=4/11$