Generalized phonon density of states of La2−xSrxCuO4cuprate superconductor

Abstract

Many body quantum dynamics of phonons is steadily developed by considering the various effects of anharmonicities, defects (consider as doping or impurity concentration) and electron–phonon interactions in model Hamiltonian (instead of BCS Hamiltonian) for a high-temperature superconductor (HTS). This enables to obtain the expressions for the renormalized phonon spectrum, the renormalized phonon density of states (RPDOS). The RPDOS can be resolved into diagonal and nondiagonal parts where the nondiagonal component is found highly impurity-dependent. Considering the suitable Born–Mayer–Huggins (BMH) interaction potential, the renormalized phonon spectrum, RPDOS and generalized phonon density of states (GPDOS) of the La[Formula: see text]Sr[Formula: see text]CuO4layered superconductor have been numerically analyzed and it was found that these quantities depend on doping concentration, anharmonicities, and temperature. The results are compared with the inelastic neutron scattering experimental data of GPDOS for La[Formula: see text]Sr[Formula: see text]CuO4and are found in good agreement. The ratio of deviation in GPDOS to GPDOS at critical temperature ([Formula: see text] K) shows the implicit difference at [Formula: see text]. The impact of defects, anharmonicities, and electron–phonon interactions in the cuprate superconductors virtually modify the scenario of GPDOS and affirm a large number of exotic peaks in the spectrum.