2019/05/20 by Jeremías Aguilera Damia, Jeremias Aguilera Damia, Shamit Kachru +3 · 54 citations
Mathematics · Physics and Astronomy · #Exponent #Fermi liquid theory #Fermion #Geometry #Mathematical physics #Mathematics #Order (exchange) #Physics #Physics of Superconductivity and Magnetism #Quantum #Quantum critical point #Quantum mechanics #Quantum phase transition #Quasiparticle #Rare-earth and actinide compounds #Saddle point #Superconductivity #Theoretical and Computational Physics #cond-mat.str-el #cond-mat.supr-con #hep-th
paper · pdf · doi:10.1103/physrevlett.123.096402
published in Physical Review Letters 123(9), 096402 (American Physical Society) · 8 pages, two columns, 2 figures
arxiv created 2019/05/20 · openalex created_date 2019/05/29 · openalex publication_date 2019/08/29 · arxiv updated 2019/09/04 · openalex updated_date 2026/08/06
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-N limit (N 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 SU(N) flavor symmetry, while the order parameter fields transform under the adjoint representation (a "matrix large-N" theory), yields a tractable large N limit. At low energies, the system consists of an overdamped boson with dynamical exponent z=3 coupled to a non-Fermi-liquid with self-energy Σ(ω)∼ω2/3, consistent with previous studies.