NMR studies on the new iron arsenide superconductors including the superconducting state

We summarize our Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) results on the new iron arsenide superconductor LaO1-xFxFeAs in the normal state, and show new NMR data in the superconducting state. Beyond early evidence of nodes and spin-singlet pairing[2], we find evidence of a deviation of the T3 behaviour of the spin lattice relaxation rate, 1/T1, at temperatures significantly below Tc, which would agree with the suggested extended s-wave symmetry. The deviation of the T3 behaviour is induced by the pair breaking effect of impurities. Different amounts of impurities would lead to different temperature dependences of 1/T1, which would allow to differentiate between d-wave and extended s-wave symmetries.