Superconductivity and spin fluctuations in the electron-doped infinitely-layered high T c superconductor Sr 0.9La 0.1CuO 2 ( Tc = 42 K)

Abstract

We report 63Cu NMR studies on uniaxially aligned and unaligned powder samples of an electron-doped infinitely-layered high T c cuprate superconductor Sr 0.9 La 0.1 CuO 2 ( T c = 42 K). We measured the nuclear spin-lattice relaxation rate 1 T 1 up to 800 K. We found from the temperature dependence of 1 T 1 T that the wave-vector-averaged spin susceptibility is highly enhanced by spin-fluctuations in the normal state, resulting in a Curie-Weiss behavior. Below T c, we did not observe a Hebel-Slichter coherence peak of 1 T 1 , suggesting an unconventional nature of the symmetry of the superconducting order parameter. These results are quite similar to those observed for some hole-doped high T c cuprates.