Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 33: Low-dimensional Systems - Models II

TT 33.7: Talk

Friday, March 30, 2007, 12:00–12:15, H18

Fractional charges and spin-charge separation in one-dimensional Wigner lattices — Maria Daghofer and •Peter Horsch — MPI for Solid State Research, Stuttgart, Germany

We study density response N(k,ω) and one-particle spectra A(k,ω) for a Wigner lattice model at quarter filling using exact diagonalization. These spectra show clear signatures of charge fractionalization into pairs of domain walls, whose interaction can be attractive or repulsive and is controlled by the formal fractional charges. In striking contrast to a bound exciton in N(k,ω), we find an antibound quasi-particle in A(k,ω), which undergoes spin-charge separation. We present a case of extreme particle-hole asymmetry, where photoemission shows spin-charge separation, while inverse photoemission exhibits uncorrelated one-particle bands.

Inclusion of the spin degree of freedom reduces the stability region of the Wigner crystal in the phase diagram. For some parameters, the system becomes ferromagnetic.