Stripe Formation in the Fractional Quantum Hall Regime

An understanding of the physics of the half-filled lowest Landau level has been achieved in terms of a Fermi sea of composite fermions, but the nature of the state at other even-denominator fractions has remained unclear. We investigate theoretically Landau level fillings of the form $\nu =(2n+1)/(4n+4)$, which correspond to composite-fermion fillings ${\nu }^{*}=n+1/2\mathrm{}$. By considering various plausible candidate states with complete spin polarization, we rule out the composite-fermion Fermi sea and paired composite-fermion state at these filling factors, and predict that the system phase separates into stripes of $n$ and $n+1\mathrm{}$ filled Landau levels of composite fermions.