Evidence of Incoherent Carriers Associated with Resonant Impurity Levels and Their Influence on Superconductivity in the Anomalous Superconductor Pb1−xTlxTe

• Published in: Physical review letters 2018-11, Vol.121 (20), p.207001
• Main Authors: Giraldo-Gallo, P, Walmsley, P, Sangiorgio, B, Riggs, S C, McDonald, R D, Buchauer, L, Fauqué, B, Liu, Chang, Spaldin, N A, Kaminski, A, Behnia, K, Fisher, I R
• Format: Article
• Language: English
• Subjects: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Density functional theory; Electronic structure; Fermi surfaces; Hall effect; High temperature; Impurities; Photoelectric emission; Superconductivity; Thallium; Valence band
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.121.207001

We present a combined experimental and theoretical study of the evolution of the Fermi surface of the anomalous superconductor Pb1−xTlxTe as a function of thallium concentration, drawing on a combination of magnetotransport measurements (Shubnikov–de Haas oscillations and the Hall coefficient), angle resolved photoemission spectroscopy, and density functional theory calculations of the electronic structure. Our results indicate that for Tl concentrations beyond a critical value, the Fermi energy coincides with resonant impurity states in Pb1−xTlxTe, and we rule out the presence of an additional valence band maximum at the Fermi energy. A comparison to nonsuperconducting Pb1−xNaxTe implies that the presence of these impurity states at the Fermi energy provides the enhanced pairing interaction and thus also the anomalously high temperature superconductivity in this material.