Systematic study of short-range antiferromagnetic order and the spin-glass state in lightly doped La2-xSrxCuO4

Systematic measurements of the magnetic susceptibility were performed on single crystals of lightly doped La2-xSrxCuO4 (x = 0.03, 0.04, and 0.05). for all samples the temperature dependence of the in-plane magnetic susceptibility shows typical spin-glass features with spin-glass transition temperatures T-g of 6.3; 5.5, and 5.0 K for x = 0.03, 0.04, and 0.05, respectively. The canonical spin-glass order parameter extracted from the in-plane susceptibility of all the samples follows a universal scaling curve. On the other hand, the out-of-plane magnetic susceptibility deviates from Curie law below a temperature T-dv higher than T-g. Comparing with previous neutron-scattering results with an instrumental energy resolution of Delta omega similar to 0.25 meV from Wakimoto et al., the x dependence of T-dv is qualitatively the same as that of T-el (Delta omega = 0.25 meV), the temperature below which the elastic magnetic scattering develops around (pi, pi). Thus a revised magnetic phase diagram in the lightly doped region of La2-xSrxCuO4 is proposed. The Curie constants calculated from the in-plane susceptibility are independent of the Sr concentration. On the basis of the cluster spin-glass model, this fact might reflect an inhomogeneous distribution of doped holes in the CuO2 plane, such as in a stripe structure.