Possible unconventional superconductivity in substituted BaFe2As2 revealed by magnetic pair-breaking studies

• Published in: Scientific reports Vol. 4; no. 1; p. 6252
• Main Authors: Rosa, P. F. S., Adriano, C., Garitezi, T. M., Piva, M. M., Mydeen, K., Grant, T., Fisk, Z., Nicklas, M., Urbano, R. R., Fernandes, R. M., Pagliuso, P. G.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.09.2014; Nature Publishing Group
• Subjects: 639/301/119/997; 639/766/119/1003; Crystals; Electron spin resonance; Electrons; Humanities and Social Sciences; multidisciplinary; Pressure; Science; Temperature effects; Transition temperatures
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep06252

The possible existence of a sign-changing gap symmetry in BaFe 2 As 2 -derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe 1.9 M 0.1 As 2 ( M = Mn, Co, Cu and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for M = Cu and Mn compounds, which display very low SC transition temperature ( T c ) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of T c cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials.