"Non-Fermi-liquid behavior of large-NB quantum critical metals"

A. Liam Fitzpatrick: Shamit Kachru, Jared Kaplan, and S. Raghu; Physical Review B, 04/11/14.

Additional Authors: Shamit Kachru, Jared Kaplan, and S. Raghu

Abstract:

The problem of continuous quantum phase transitions in metals involves critical bosons coupled to a Fermi surface. We solve the theory in the limit of a large number, NB, of bosonic flavors, where the bosons transform in the adjoint representation (a matrix representation), while the fermions are in the fundamental representation (a vector representation) of a global SU(NB) flavor symmetry group. The leading large NB solution corresponds to a non-Fermi liquid coupled to Wilson-Fisher bosons. In a certain energy range, the fermion velocity vanishes—resulting in the destruction of the Fermi surface. Subleading 1/NB corrections correspond to a qualitatively different form of Landau damping of the bosonic critical fluctuations. We discuss the model in d=3−ε but because of the additional control afforded by large NB, our results are valid down to d=2. In the limit ε≪1, the large NB solution is consistent with the renormalization group analysis of Fitzpatrick et al. [Phys. Rev. B 88, 125116 (2013)].