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Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry.

ABSTRACT: There are few general physical principles that protect the low-energy excitations of a quantum phase. Of these, Goldstone's theorem and Landau-Fermi liquid theory are the most relevant to solids. We investigate the stability of the resulting gapless excitations--Nambu-Goldstone bosons (NGBs) and Landau quasiparticles--when coupled to one another, which is of direct relevance to metals with a broken continuous symmetry. Typically, the coupling between NGBs and Landau quasiparticles vanishes at low energies, leaving the gapless modes unaffected. If, however, the low-energy coupling is nonvanishing, non-Fermi liquid behavior and overdamped bosons are expected. Here we prove a general criterion that specifies when the coupling is nonvanishing. It is satisfied by the case of a nematic Fermi fluid, consistent with earlier microscopic calculations. In addition, the criterion identifies a new kind of symmetry breaking--of magnetic translations--where nonvanishing couplings should arise, opening a previously unidentified route to realizing non-Fermi liquid phases.

SUBMITTER: Watanabe H

PROVIDER: S-EPMC4246282 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry.

Watanabe Haruki H Vishwanath Ashvin A

Proceedings of the National Academy of Sciences of the United States of America 20141027 46

There are few general physical principles that protect the low-energy excitations of a quantum phase. Of these, Goldstone's theorem and Landau-Fermi liquid theory are the most relevant to solids. We investigate the stability of the resulting gapless excitations--Nambu-Goldstone bosons (NGBs) and Landau quasiparticles--when coupled to one another, which is of direct relevance to metals with a broken continuous symmetry. Typically, the coupling between NGBs and Landau quasiparticles vanishes at lo ...[more]

PMID: 25349386

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Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry.

Publications

Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry.

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