Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 80: Correlated Electrons: (General) Theory 2

TT 80.2: Vortrag

Donnerstag, 10. März 2016, 16:15–16:30, H18

Multiplons in the two-hole excitation spectra of the Hubbard model — •Roman Rausch and Michael Potthoff — I. Institute for Theoretical Physics, University of Hamburg

Using the density-matrix renormalization group (DMRG) in combination with the Chebyshev polynomial expansion technique, we study the two-hole excitation spectra of the one-dimensional Hubbard model from n=2 down to half-filling n=1. Experimentally, this corresponds to the Auger Electron Spectroscopy (AES). The spectra reveal multiplon physics, i.e., the relevant final states are characterized by two (doublon), three (triplon), four (quadruplon) and more holes, potentially forming stable compound objects or resonances with finite lifetime. This multiplon phenomenology is analyzed by interpreting not only the local and k-resolved two-hole spectra, but also auxiliary three- and four-hole spectra, as well as by referring to effective low-energy models and employing a filter-operator technique. In addition, we compare with the elementary excitations of the Bethe ansatz, which in particular reveals the decay channels of the doublon into spinons and holons in one dimension. For all fillings with n>1, the doublon lifetime is strongly k-dependent and even infinite at the Brillouin zone edges. This can be traced back to the “hidden” charge-SU(2) symmetry of the model. We briefly discuss how this k-dependence changes in two dimensions, by applying DMRG to small-radius cylinders, as well as extrapolating to larger systems by using cluster perturbation theory (CPT).
R. Rausch, M. Potthoff, arXiv:1510.01162