# Muon spin rotation and infrared spectroscopy study of magnetism and superconductivity in ${\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{K}}_{x}{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$

• Mallett, Benjamin P. P. Robinson Research Institute, Victoria University, Wellington, New Zealand - University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Switzerland
• Wang, Chen Nan University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Switzerland - Masaryk University, Department of Condensed Matter Physics and CEITEC–Central European Institute of Technology, Brno, Czech Republic
• Marsik, Premysl University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Switzerland
22.02.2017
Published in:
• Physical Review B. - 2017, vol. 95, no. 5, p. 054512
English Using muon spin rotation and infrared spectroscopy, we study the relation between magnetism and superconductivity in Ba1−xKxFe2As2 single crystals from the underdoped to the slightly overdoped regime. We find that the Fe magnetic moment is only moderately suppressed in most of the underdoped region where it decreases more slowly than the Néel temperature TN. This applies for both the total Fe moment obtained from muon spin rotation and for the itinerant component that is deduced from the spectral weight of the spin-density-wave pair-breaking peak in the infrared response. In the moderately underdoped region, superconducting and static magnetic orders coexist on the nanoscale and compete for the same electronic states. The static magnetic moment disappears rather sharply near optimal doping, however, in the slightly overdoped region there is still an enhancement or slowing down of spin fluctuations in the superconducting state. Similar to the gap magnitude reported from specific-heat measurements, the superconducting condensate density is nearly constant in the optimally and slightly overdoped region, but exhibits a rather pronounced decrease on the underdoped side. Several of these observations are similar to the phenomenology in the electron-doped counterpart Ba(Fe1−yCoy)2As2.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
• English
Classification
Physics