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Effective action and collective modes in quasi-one-dimensional spin-density-wave systems

K. Sengupta·N. Dupuis
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Abstract

We derive the effective action describing the long-wavelength low-energy collective modes of quasi-one-dimensional spin-density-wave (SDW) systems, starting from the Hubbard model within weak coupling approximation. The effective action for the spin-wave mode corresponds to an anisotropic non-linear sigma model together with a Berry phase term. We compute the spin stiffness and the spin-wave velocity. We also obtain the effective action for the sliding mode (phason) taking into account the density fluctuations from the outset and in presence of a weak external electromagnetic field. This leads to coupled equations for the phase of the SDW condensate and the charge density fluctuations. We also calculate the conductivity and the density-density correlation function.

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K. Sengupta, N. Dupuis. 2000-01-26. Effective action and collective modes in quasi-one-dimensional spin-density-wave systems. https://doi.org/10.1103/physrevb.61.13493

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