Spin-charge fluctuations in itinerant helical magnets


  • Wolfram Brenig

    1. Institut für Theoretische Physik, Universität zu Köln, D-50937 Köln, Germany and Physikalisches Institut, Theoretische Physik I, Universität Bayreuth, D-95440 Bayreuth, Germany
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Using a generalized random phase approach quantum fluctuations beyond the helical mean-field states of the Hubbard model off half filling are discussed. The collective mode spectrum is shown to exhibit spin-charge mixing and is found to be strongly renormalized by coupling to low-energy incoherent particle-hole excitations. Results for the collective mode dispersion which displays a significant anisotropy are presented for selected helical phases. Moreover phase space regions of ‘missing’ modes are identified with a finite wave length instability of the helical states suggesting novel inhomogeneous phases of the doped Hubbard model.

P.A.C.S. : 71.27.+a, 75.30.Fv, 75.40.Gb