Study of the quantum phase transition to a nematic and an hexatic Fermi fluid

V. FERNÁNDEZ, M. TROBO, D. BARCI Y L. OXMAN

Buenos Aires, Argentina

Workshop; At the Frontiers of Condensed Matter III; 2006

We study a two-dimensional Fermi fluid by means of bosonization. Wediscuss Pomeranchuk instabilities of the Fermi surface of thissystem. In particular, we are interested on the quantum criticalbehavior of the transition from a Fermi fluid to a nematic  and toan hexatic state which break spontaneously the rotational invarianceof the Fermi liquid. The nematic phase was recently observed in halffilled quantum Hall systems and it was proposed as a candidated tothe ``normal state'' of high $T_c$ superconductors. On the otherhand, the hexatic phase can be understood as a melted Wigner crystal,therefore justifying the study of its competition with the nematicand the isotropic phase. We carefully study  the phase diagram forthe isotropic/nematic/hexatic quantum phase transition evaluating inparticular the dynamics of the collective modes that could beobserved in scattering experiments.