Amplitude mode of the d-density wave state and its relevance to high-Tc cuprates

We study the spectrum of the amplitude mode, the analog
of the Higgs mode in high energy physics, for the d-density wave (DDW) state
proposed to describe the anomalous phenomenology of the pseudogap phase of the
high Tc cuprates. Even though the state breaks translational symmetry by a
lattice spacing and is described by a particle-hole singlet order parameter at
the wave vector q = Q = (pi, pi), remarkably, we find that the amplitude mode
spectrum can have peaks at both q = (0, 0) and q = Q = (pi , pi). In general,
the spectra is non-universal, and, depending on the microscopic parameters, can
have one or two peaks in the Brillouin zone, signifying confluence of two kinds
of magnetic excitations. In light of the recent unexpected observations of
multiple magnetic excitations in the pseudogap phase our theory sheds important
light on how multiple inelastic neutron peaks at different wave vectors can
arise even with an order parameter that condenses at Q = (pi, pi).

[Reference: arXiv:1207.6834]

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Friday, November 30, 2012 - 13:00 to 14:30
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