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Register a new userOptical conductivity of the Hubbard chain away from half filling
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Added by
Alexander C. Tiegel
Publication date
2016
fields
Physics
and research's language is
English
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We consider the optical conductivity $sigma_1(omega)$ in the metallic phase of the one-dimensional Hubbard model. Our results focus on the vicinity of half filling and the frequency regime around the optical gap in the Mott insulating phase. By means of a density-matrix renormalization group implementation of the correction-vector approach, $sigma_1(omega)$ is computed for a range of interaction strengths and dopings. We identify an energy scale $E_{rm opt}$ above which the optical conductivity shows a rapid increase. We then use a mobile impurity model in combination with exact results to determine the behavior of $sigma_1(omega)$ for frequencies just above $E_{rm opt}$ which is in agreement with our numerical data. As a main result, we find that this onset behavior is not described by a power law.
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We study the half filled Hubbard chain including next-nearest-neighbor hopping $t$. The model has three phases: one insulating phase with dominant spin-density-wave correlations at large distances (SDWI), another phase with dominant spin-dimer correlations or dimerized insulator (DI), and a third one in which long distance correlations indicate singlet superconductivity (SS). The boundaries of the SDWI are accurately determined numerically through a crossing of excited energy levels equivalent to the jump in the spin Berry phase. The DI-SS boundary is studied using several indicators like correlation exponent $K_{rho}$, Drude weight $D_{c}$, localization parameter $z_{L}$ and charge gap $Delta_{c}$.
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