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Optical conductivity near finite-wavelength quantum criticality

S. Caprara·M. Grilli·C. Di Castro·T. Enss
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Abstract

We study the optical conductivity sigma(Omega) of an electron system near a quantum-critical point with finite-wavelength ordering. sigma(Omega) vanishes in clean Galilean-invariant systems, unless electrons are coupled to dynamical collective modes, which dissipate the current. This coupling introduces a nonuniversal energy scale. Depending on the parameters of each specific system, a variety of responses arise near criticality: scaling peaks at a temperature- and doping-dependent frequency, peaks at a fixed frequency, or no peaks to be associated with criticality. Therefore the lack of scaling in the far-infrared conductivity in cuprates does not necessarily call for new concepts of quantum criticality.

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S. Caprara, M. Grilli, C. Di Castro, T. Enss. 2007-04-18. Optical conductivity near finite-wavelength quantum criticality. https://doi.org/10.1103/physrevb.75.140505

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