A Bogoliubov-de Gennes study of d-wave Hubbard superconductors under magnetic field

The formation of magnetic vortices and their effects on the electronic specific heat (C-el) of d-wave superconductors are studied within the generalized Hubbard model and the Bogoliubov-de Gennes (BdG) formalism. The BdG equations provide the local superconducting gaps as a function of the electron-electron interaction and carrier concentration. The electron hopping parameters of the generalized Hubbard model for the ceramic superconductor La2-xSrxCuO4 are determined by using angle-resolved photoemission spectroscopy (ARPES) data. The BdG results show that the d-wave superconducting states, induced by the correlated hopping interactions, possess an upper-critical-magnetic-field temperature dependence consistent with the generalized Ginzburg-Landau model for type II superconductors. Furthermore, the electronic specific heat reveals a square-power-law temperature behavior observed in d-wave superconductors. When an external magnetic field is applied, such behavior becomes linear at the low-temperature limit. The coefficient of this linear behavior confirms the square-root dependence with the external magnetic field predicted by the Volovik thermodynamic model and its trend is consistent with experimental data obtained from La1.85 Sr0.15CuO4.