Marsik, Premysl Wang, Chen Nan Rössle, Matthias Yazdi-Rizi, M. Schuster, Roman Kim, Kyung Wan Dubroka, Adam Munzar, Dominik Wolf, T. Chen, X. H. Bernhard, Christian 2013-11-15 We studied the doping and temperature (T) dependence of the infrared (IR) response of Ba(Fe1−xCox)2As2 single crystals. We show that a weak band around 1000 cm−1, that was previously interpreted in terms of interaction of the charge carriers with magnetic excitations or of a pseudogap, is rather related to low-energy interband transitions. Specifically, we show that this band exhibits a similar doping and T dependence as the hole pockets seen by angle resolved photoemission spectroscopy (ARPES). Notably, we find that it vanishes as a function of doping near the critical point where superconductivity is suppressed in the overdoped regime. Our IR data thus provide bulk specific information (complementary to the surface sensitive ARPES) for a Lifshitz transition. Our IR data also reveal a second low-energy band around 2300 cm−1 which further emphasizes the necessity to consider the multiband nature of these iron arsenides in the analysis of the optical response. application/pdf https://folia.unifr.ch/global/documents/303556 https://folia.unifr.ch/documents/303556/files/ber_lei.pdf https://folia.unifr.ch/documents/303556/files/ber_lei_sm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.88.180508 info:eu-repo/semantics/openAccess License undefined Physical Review B. - 2014, vol. 88, no. 18, p. 180508 info:eu-repo/classification/udc/53 Low-energy interband transitions in the infrared response of Ba(Fe1-xCox)2As2 http://purl.org/coar/resource_type/c_6501