Abstract
Significant effort has been devoted to the study of “non-Fermi-liquid” (NFL) metals: gapless conducting systems that lack a quasiparticle description. One class of NFL metals involves a finite density of fermions interacting with soft order parameter fluctuations near a quantum critical point. The problem has been extensively studied in a large- limit ( corresponding to the number of fermion flavors) where universal behavior can be obtained by solving a set of coupled saddle-point equations. However, a remarkable study by Lee revealed the breakdown of such approximations in two spatial dimensions. We show that an alternate approach, in which the fermions belong to the fundamental representation of a global flavor symmetry, while the order parameter fields transform under the adjoint representation (a “matrix large-” theory), yields a tractable large limit. At low energies, the system consists of an overdamped boson with dynamical exponent coupled to a non-Fermi-liquid with self-energy , consistent with previous studies.
- Received 4 June 2019
DOI:https://doi.org/10.1103/PhysRevLett.123.096402
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