Diamond chain with delocalized interstitial spins: Magnetization, thermal and entanglement properties

We study physical properties of the symmetric diamond chain with delocalized interstitial spins. We derive an exact solution of the model and characterize the phases of the system at zero temperature. On the basis of this solution, we examine its magnetic and thermal properties as well. The case of nonconserved electron number is then considered. There are phases, which we term as nonclassical, for which electrons in Hubbard dimers are in quantum entangled states. We finally study quantum entanglement depending on Hamiltonian parameters and temperature.