Density-matrix renormalization group study of optical conductivity of the Mott insulator for two-dimensional clusters
| Autor: | Shigetoshi Sota, Kazuya Shinjo, Yoshiki Tamaki, Takami Tohyama |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Physics
Condensed Matter::Quantum Gases Strongly Correlated Electrons (cond-mat.str-el) Hubbard model Condensed matter physics Density matrix renormalization group Mott insulator FOS: Physical sciences Polaron Coupling (probability) Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Square lattice Omega Condensed Matter - Strongly Correlated Electrons Condensed Matter::Strongly Correlated Electrons Continuum (set theory) |
| Popis: | The real part of optical conductivity $\text{Re}\sigma(\omega)$ of the Mott insulators has a large amount of information on how spin and charge degrees of freedom interact with each other. By using the time-dependent density-matrix renormalization group, we study $\text{Re}\sigma(\omega)$ of the two-dimensional Hubbard model on a square lattice at half filling. We find an excitonic peak at the Mott-gap edge of $\text{Re}\sigma(\omega)$ not only for the two-dimensional square lattice but also for two- and four-leg ladders. For the square lattice, however, we do not clearly find a gap between an excitonic peak and continuum band, which indicates that a bound state is not well defined. The emergence of an excitonic peak in $\text{Re}\sigma(\omega)$ implies the formation of a spin polaron. Examining the dependence of $\text{Re}\sigma(\omega)$ on the on-site Coulomb interaction and next-nearest neighbor hoppings, we confirm that an excitonic peak is generated from a magnetic effect. Electron scattering due to an electron-phonon interaction is expected to easily suppress an excitonic peak since spectral width of an excitonic peak is very narrow. Introducing a large broadening in $\text{Re}\sigma(\omega)$ by modeling the electron-phonon coupling present in La$_{2}$CuO$_{4}$ and Nd$_{2}$CuO$_{4}$, we obtain $\text{Re}\sigma(\omega)$ comparable with experiments. Comment: 10 pages, 8 figures |
| Databáze: | OpenAIRE |
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