Pomeranchuk instability of composite Fermi liquid*

Nematicity in quantum Hall systems has been experimentally well established at excited Landau levels. The mechanism of the symmetry breaking, however, is still unknown. Pomeranchuk instability of Fermi liquid parameter F_l≤ -1 in the angular momentum l=2 channel has been hypothesized to be the relevant mechanism, yet there are no clear theoretical proofs. Here we calculate, using variational Monte Carlo technique, Fermi liquid parameters F_l of the composite Fermi liquid interacting with 1/r coulomb interaction. We consider F_l in different Landau levels n=0,1,2 as functions of layer width η. We find that unlike the lowest Landau level, which shows no sign of Pomeranchuk instability, higher Landau levels show nematic instability below critical values of η.