NMR studies of Nd2−x Ce x CuO4

Abstract

Copper NMR has been studied as a function of temperature in a number of superconducting Nd 2_~CexCuO 4 samples. The electric field gradient is very small and the Knight shift is 2380 ppm at room temperature, both of these implying that the copper is in a Cu + state. The Knight shift decreases with temperature particularly below To. The spin contribution to the Knight shift is estimated to be ~ 200 ppm (about a factor ten smaller than in YBa2Cu307) indicating that N~(Ev) at the copper sites is small in this material.