Emergent low-energy bound states in the two-orbital Hubbard model

Abstract

A repulsive Coulomb interaction between electrons in different orbitals in correlated materials can give rise to bound quasiparticle states. We study the non-hybridized two-orbital Hubbard model with intra (inter)-orbital interaction $U$ ($U_{12}$) and different band widths using an improved dynamical mean field theory numerical technique which leads to reliable spectra on the real energy axis directly at zero temperature. We find that a finite density of states at the Fermi energy in one band is correlated with the emergence of well defined quasiparticle states at excited energies $\Delta =U-U_{12}$ in the other band. These excitations are inter-band holon-doublon bound states. At the symmetric point $U=U_{12}$, the quasiparticle peaks are located at the Fermi energy, leading to a simultaneous and continuous Mott transition settling a long-standing controversy.

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• Renormalized dispersing multiplets in the spectrum of nearly Mott localized systems
• Orbital-selective bad metals due to Hund's rule and orbital anisotropy: a finite-temperature slave-spin treatment of the two-band Hubbard model
• Hund bands in spectra of multiorbital systems
• Precise ground state of multi-orbital Mott systems via the variational discrete action theory
• Excitonic density-waves, bi-excitons and orbital selective pairing in two-orbital correlated chains
• Novel subbands in the doped two-orbital Kanamori-Hubbard model
• Low-energy interband Kondo bound states in orbital-selective Mott phases
• Unconventional correlated metallic behavior due to interorbital Coulomb interaction
• Quantitative determination of the orbital-selective Mott transition and quantum entanglement in the orbital-selective Mott phase
• Bad metal and negative compressibility transitions in a two-band Hubbard model
• Low-energy structure and topology of the two-band Hubbard-Kanamori model