O-17 NMR-STUDY OF LA2-XSRXCUO4 IN THE LIGHTLY-DOPED AND HEAVILY-DOPEDREGIONS

A O-17 NMR study has been carried out for La2-xSrxCuO4 in the lightly- (x = 0.075) and heavily-doped (x = 0.24) regions in the normal state. Together with the data previously reported for x = 0.15, it was found that the nuclear quadrupole frequency v(Q) in the apical oxygen (O(1) ) does not change with x, suggesting that the doped hole does not go i nto the LaO layer at all. On the contrary, PQ in the planar oxygen (O( 2)) increases appreciably with Sr doping. By analyzing v(Q) of Cu and O(2), it was shown that the increase of holes on the planar O 2p(sigma ) orbit is more appreciable than that in the Cu 3d orbit. From the rat io of the hole density in Cu to that in oxygen, and the spin fluctuati on probed by 63(T1T), it is suggested that the depression of T(c) in t he ''heavily-doped'' region is neither due to the over-doping nor to t he collapse of the two-dimensionality, but to other causes. The temper ature dependences of the Knight shift 17K in two samples are in sharp contrast with each other. In the lightly-doped region, 17K decreases w ith decreasing temperature. In the heavily-doped region, however, 17K increases slightly with decreasing temperature, becoming almost T-inde pendent below 100 K. An increase of the anisotropic part of spin Knigh t shift 17K(s,ani) with x also indicates that the hole density at the O 2p(sigma) orbit increases with Sr doping.