The Effect Of Impurity In Heavy Fermion Superconductor CeCu₂Si₂

Heavy fermion superconducting materials have been an important part of superconducting materials research.Superconducting material CeCu2Si2 has been attracting attention because of its unique physical prop erties-ant iferro magnetic properties coexisting with superconductivity,and its pairing symmetry and pairing mechanism is unclear,at the same time,there are some controversies in the Fermi surface.Antiferromagnetic spin fluctuation is one of the important causes of superconductivity,and the related studies shown that the superconductivity of CeCu2Si2 under normal pressure is caused by antiferromagnetic spin fluctuation and the d-wave pairing symmetry-related physical properties are show.To reveal the syperconducting microscopic mechanism of heavy-fermion superconductor CeCu2Si2,starting from the single-band model and applying the T-matrix approach and Green's function,we discuss the quasiparticle scattering interference phenomenon in the presence of a single nonmagnetic impurity by calculating the strong potential scattering local state density of quasiparticle and energy and momentum dependence of the Fourier transformed local density of states in the full Brillouin zone,that is,OPI image,and the topological structure of two-dimensional Fermi surface is fitted.dx2-y2 and dxy paring symmetry because the mainly considered.With the energy increasing,the position of the local peaks in the Brillouin zone move rapidly and the spectrum weight change,this is consistent with the contours of constant energy(CCE).At the strong scattering potential,there are differences in the local electron density under the symmetry of the two d-wave pairs,the impurity-induced resonance peak arise near the Fermi energy,but the superconducting peaks are suppressed.The spatial pattern of both dx2-y2 and dxy pairing are related to the nodal line of the gap structures.If this theoretical derivation is consistent with the scanning tunneling experiment(STM)results,we will further confirm its superconducting pairing mechanism.