Low-energy interband transitions in the infrared response of Ba(Fe1-xCox)(2)As-2

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Authors	MARŠÍK Přemysl WANG C. N. ROESSLE M. YAZDI-RIZI M. SCHUSTER Roman KIM K. W. DUBROKA Adam MUNZAR Dominik WOLF T. CHEN X. H. BERNHARD Christian
Year of publication	2013
Type	Article in Periodical
Magazine / Source	Physical Review B
MU Faculty or unit	Central European Institute of Technology
Citation
Web	http://prb.aps.org/abstract/PRB/v88/i18/e180508
Doi	http://dx.doi.org/10.1103/PhysRevB.88.180508
Field	Solid matter physics and magnetism
Keywords	T-C SUPERCONDUCTORS; TEMPERATURE SUPERCONDUCTIVITY; IRON; ELECTRODYNAMICS
Description	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.
Related projects:	CEITEC - Central European Institute of Technology