Local Electronic Structure of a Single Nonmagnetic Impurity as a Test of the Pairing Symmetry of Electrons in $(\mathrm{K},\mathrm{Tl}){\mathrm{Fe}}_{x}{\mathrm{Se}}_{2}$ Superconductors

Local Electronic Structure of a Single Nonmagnetic Impurity as a Test of the Pairing Symmetry of Electrons in $(K, Tl) {Fe}_{x} {Se}_{2}$ Superconductors

Jian-Xin Zhu, Rong Yu, A. V. Balatsky, and Qimiao Si

Phys. Rev. Lett. 107, 167002 – Published 14 October 2011

Abstract

We study the effect of a single nonmagnetic impurity on the recently discovered $(K, Tl) {Fe}_{x} {Se}_{2}$ superconductors, within both a toy two-band model and a more realistic five-band model. We find that, out of five types of pairing symmetry under consideration, only the $d_{x^{2} - y^{2}}$ -wave pairing gives rise to impurity resonance states. The intragap states have energies far away from the Fermi energy. The existence of these intragap states is robust against the presence or absence of interband scattering. However, the interband scattering does tune the relative distribution of local density of states at the resonance states. All these features can readily be accessed by STM experiments, and are proposed as a means to test the pairing symmetry of the new superconductors.

Received 3 April 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.167002

Authors & Affiliations

Jian-Xin Zhu^1,*, Rong Yu², A. V. Balatsky^1,3, and Qimiao Si²

¹Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
²Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
³Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA