Collective modes in unconventional density waves
The Abdus Salam ICTP - P.O. Box 586, Trieste, I-34014, Italy
2 Department of Physics, Technical University of Budapest H-1521 Budapest, Hungary
3 Research Institute for Solid State Physics and Optics P.O. Box 49, H-1525 Budapest, Hungary
Accepted: 21 November 2002
We have investigated the collective modes of unconventional charge and spin density waves (UCDW, USDW) in quasi–one dimensional systems in random phase approximation. The density correlator regains its normal-state form due to the phase degree of freedom of the condensate. The possible effect of impurities is also discussed. From this, the current-current correlation function is evaluated through charge conservation. The spin susceptibility of USDW remains anisotropic in spite of the lack of any periodic modulation of the spin density. In UCDW, the spin response gets weaker in all three directions as the temperature is lowered.
PACS: 75.30.Fv – Spin-density waves / 71.45.Lr – Charge-density-wave systems / 73.20.Mf – Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
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