Competing Magnetic Fluctuations in Iron Pnictide Superconductors: Role of Ferromagnetic Spin Correlations Revealed by NMR
In the iron pnictide superconductors, theoretical calculations have consistently shown enhancements of the static magnetic susceptibility at both the stripe-type antiferromagnetic and in-plane ferromagnetic (FM) wave vectors. However, the possible existence of FM fluctuations has not yet been examined from a microscopic point of view. Here, using 75As NMR data, we provide clear evidence for the existence of FM spin correlations in both the hole- and electron-doped BaFe2As2 families of iron-pnictide superconductors. These FM fluctuations appear to compete with superconductivity and are thus a crucial ingredient to understanding the variability of Tc and the shape of the superconducting dome in these and other iron-pnictide families.
This article is published as Wiecki, P., B. Roy, D. C. Johnston, S. L. Bud’ko, P. C. Canfield, and Y. Furukawa. "Competing magnetic fluctuations in iron pnictide superconductors: role of ferromagnetic spin correlations revealed by NMR." Physical Review Letters 115, no. 13 (2015): 137001. DOI: 10.1103/PhysRevLett.115.137001. Posted with permission.