Controlled expansion for certain non-Fermi-liquid metals
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Mross-2010-Controlled expansion.pdf
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Author(s)
Mross, David Fabian
McGreevy, John
Liu, Hong
Senthil, Todadri
Date Issued
July 2010
Journal
Physical Review B
Publisher
American Physical Society
Citation
Mross, David F. et al. "Controlled expansion for certain non-Fermi-liquid metals." Physical Review B 82.4(2010): 045121. © 2010 The American Physical Society
Version
Final published version
Abstract
The destruction of Fermi-liquid behavior when a gapless Fermi surface is coupled to a fluctuating gapless boson field is studied theoretically. This problem arises in a number of different contexts in quantum many-body physics. Examples include fermions coupled to a fluctuating transverse gauge field pertinent to quantum spin-liquid Mott insulators, and quantum critical metals near a Pomeranchuk transition. We develop a controlled theoretical approach to determine the low-energy physics. Our approach relies on combining an expansion in the inverse number (N) of fermion species with a further expansion in the parameter ϵ=zb−2, where zb is the dynamical critical exponent of the boson field. We show how this limit allows a systematic calculation of the universal low-energy physics of these problems. The method is illustrated by studying spinon Fermi-surface spin liquids, and a quantum critical metal at a second-order electronic nematic phase transition. We calculate the low-energy single-particle spectra, and various interesting two-particle correlation functions. In some cases, deviations from the popular random-phase approximation results are found. Some of the same universal singularities are also calculated to leading nonvanishing order using a perturbative renormalization-group calculation at small N extending previous results of Nayak and Wilczek. Implications for quantum spin liquids and for Pomeranchuk transitions are discussed. For quantum critical metals at a nematic transition, we show that the tunneling density of states has a power-law suppression at low energies.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.82.045121
