Spin susceptibility in the La2-xSrxCuO4 system from underdoped to overdoped regimes

Cu63 NMR Knight shifts were measured on La1-xSrxCuO4 for x=0.10, 0.16, and 0.20 in the normal and superconducting states. These results, combined with magnetic susceptibility measurements, allow the separation of the carrier spin and orbital contributons to the susceptibility. At temperatures just above the superconducting transition, the conduction electron spin susceptibility increases dramatially with strontium doping. The analysis of the Knight shift at low temperature suggests that the spin susceptibility is zero and the superconducting state is a spin singlet.