Second-order perturbation theory for the single-impurity Anderson model of a BCS superconductor

Tutkimustuotos: Lehtiartikkelivertaisarvioitu

Tutkijat

  • Ari T. Alastalo

Organisaatiot

  • Aalto University

Kuvaus

This paper presents a conserving approximation for a single magnetic impurity embedded in a BCS superconductor according to the Anderson model. The calculation generalizes the second-order selfenergy theory of a normal metal host into a superconducting medium. Within the second-order theory, both spin and pairing fluctuations contribute to the selfenergy. The second-order theory removes the unphysical spontaneous symmetry breaking of the Hartree-Fock approximation but results in a doubling of the bound-state spectrum within the energy gap. The HF bound states may be recovered in the small-U limit as the average of the two separate bound states. For increasing U, the novel pronounced low-energy bound states tend towards the center of the gap while the other bound states approach the gap edge and their spectral weights vanish.

Yksityiskohdat

AlkuperäiskieliEnglanti
Sivut193-203
Sivumäärä11
JulkaisuJournal of Magnetism and Magnetic Materials
Vuosikerta438
TilaJulkaistu - 15 syyskuuta 2017
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

ID: 13265443