The magnetic phase diagram of La2-xSr x Cu04 in the antiferromagnetic regime (x<0.02) has been derived from ,39 La nuclear quadrupole resonance studies from 4 to 250 K. The data demonstrate freezing of the doped holes' effective spin degrees of freedom below 7/~ (815 K)x into a spin-glass-like state which is superimposed on the antiferromagnetic background. These and previous results allow a detailed magnetic phase diagram to be constructed for x < 0.05 and reveal a distinct crossover at x ~ 0.02 in the nature of the spin-glass transition.

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