A. Virosztek et K. Maki, PHASON MODES IN A SPIN-DENSITY-WAVE IN THE PRESENCE OF LONG-RANGE COULOMB INTERACTION, Physical review. B, Condensed matter, 49(9), 1994, pp. 6074-6077
We study the effect of long-range Coulomb interaction on the phason in
spin-density waves (SDW's) within mean-field theory. In the longitudi
nal limit and in the absence of SDW pinning, the phason is completely
absorbed by the plasmon due to the Anderson-Higgs mechanism. In the pr
esence of SDW pinning or when the wave vector q is tilted from the cha
in direction, though the plasmon still almost exhausts the optical sum
rule, another optical mode appears at omega < 2DELTA(T), with small o
ptical weight. This low-frequency mode below the SDW gap may be access
ible to electron-energy-loss spectroscopy.