Spin-charge separation in an extended Hubbard model: a large D study

J. L. Smith, Qimiao Si A

Mona Berciu, Sajeev John

V. E. Korepin

C. Kübert, Alejandro Muramatsu

S. Ohmura, A. Takahashi, Kaoru Iwano +5 more

We propose an effective model called the ``charge model,'' for the half-filled one-dimensional Hubbard and extended Hubbard models. In this model, spin-charge separation, which has been justified from an infinite on-site repulsion ($U$) in the strict sense, is compatible with charge fluctuations. Our analyses based on the many-body Wannier functions succeeded in determining the optical conductivity spectra in large systems. The obtained spectra reproduce the spectra for the original models well even in the intermediate $U$ region of $U=5$--$10T$, with $T$ being the nearest-neighbor electron hopping energy. These results indicate that the spin-charge separation works fairly well in this intermediate $U$ region against the usual expectation and that the charge model is an effective model that applies to actual quasi-one-dimensional materials classified as strongly correlated electron systems.

Qimiao Si A

I summarize recent work on non-Fermi liquids within a certain generalized Anderson impurity model as well as in the large-dimensionality (D) limit of the two-band extended Hubbard model. The competition between local charge and spin fluctuations leads either to a Fermi liquid with renormalized quasiparticle excitations, or to non-Fermi liquids with spin - charge separation. These results provide new insights into the phenomenological similarities and differences between different correlated metals. While presenting these results, I outline a general strategy of local approach to non-Fermi liquids in correlated electron systems.