Impurity-induced subgap bound states in alkali-doped iron chalcogenide superconductors

TY - JOUR

T1 - Impurity-induced subgap bound states in alkali-doped iron chalcogenide superconductors

AU - Mukherjee, Shantanu

AU - Navarro Gastiasoro, Maria

AU - Andersen, Brian Møller

PY - 2013/10/11

Y1 - 2013/10/11

N2 - Measurements of the local density of states near impurities can be useful for identifying the superconducting gap structure in alkali-doped iron chalcogenide superconductors KxFe2-ySe2. Here, we study the effects of nonmagnetic and magnetic impurities within a nearest-neighbor d-wave and next-nearest-neighbor s-wave superconducting state. For both repulsive and attractive nonmagnetic impurities, it is shown that subgap bound states exist only for d-wave superconductors with the positions of these bound states depending rather sensitively on the electron doping level. Further, for such disorder, Coulomb interactions can lead to local impurity-induced magnetism in the case of d-wave superconductivity. For magnetic impurities, both s-wave and d-wave superconducting states support subgap bound states. The above results can be explained by a simple analytic model that provides a semiquantitative understanding of the variation of the impurity bound states energies as a function of impurity potential and chemical doping level.

AB - Measurements of the local density of states near impurities can be useful for identifying the superconducting gap structure in alkali-doped iron chalcogenide superconductors KxFe2-ySe2. Here, we study the effects of nonmagnetic and magnetic impurities within a nearest-neighbor d-wave and next-nearest-neighbor s-wave superconducting state. For both repulsive and attractive nonmagnetic impurities, it is shown that subgap bound states exist only for d-wave superconductors with the positions of these bound states depending rather sensitively on the electron doping level. Further, for such disorder, Coulomb interactions can lead to local impurity-induced magnetism in the case of d-wave superconductivity. For magnetic impurities, both s-wave and d-wave superconducting states support subgap bound states. The above results can be explained by a simple analytic model that provides a semiquantitative understanding of the variation of the impurity bound states energies as a function of impurity potential and chemical doping level.

U2 - 10.1103/PhysRevB.88.134508

DO - 10.1103/PhysRevB.88.134508

M3 - Journal article

SN - 2469-9950

VL - 88

JO - Physical Review B

JF - Physical Review B

IS - 13

M1 - 134508

ER -