NMR and NQR on LaO1−xFx FeAs in the Superconducting State
In the following, NMR and NQR measurements in the superconducting state of underdoped and optimally-doped LaO1−xF x FeAs with x = 0.05, x = 0.075 and x = 0.1 will be shown and discussed within possible gap symmetries. The presentation of the data is focussed on dynamic properties. Spin-lattice relaxation rate data for x = 0.05, x = 0.075 and x = 0.1 will be shown and analysed in Section 7.1. Section 7.2 reports the special case of LaO0.9F0.1FeAs1−δ, an optimally-doped sample with additional impurities (arsenic vacancies), exhibiting slightly enhanced superconducting properties and an even sharper decrease of T-11 than optimally-doped LaO0.9F0.1FeAs.