ON THE LOCAL MAGNETIC ORDER IN LA2-XSRXCUO4-DELTA (0 LESS-THAN-OR-EQUAL-TO X LESS-THAN-OR-EQUAL-TO 0.15)

The Sn-119 Mossbauer effect technique (300-4.2 K) has been used to study the local magnetic order in La2-xSrx(Cu0.995Sn0.005)O4+delta for three different Sr concentrations corresponding to the antiferromagnetic state (x = 0), the spin-glass-like state (x = 0.04), and the superconducting state (x = 0.15). Contrary to previous reports we observe no transferred hyperfine (hf) field at the Sn nuclei in the superconducting state down to 1.7 K. On the other hand, we observe small transferred hf fields in both the antiferromagnetic (x = 0) and the spin-glass-like state (x = 0.04). In the spin-glass-like sample (x = 0.04) we find in the temperature range 10 K less-than-or-equal-to T less-than-or-equal-to 200 K a significant increase of the Mossbauer linewidth and an anomalous change of the quadrupole splitting which we attribute to a short range structural disorder as recently reported by perturbed angular correlation measurements of In-111 on La2-xSrxCuO4 (0 less-than-or-equal-to x less-than-or-equal-to 0.07). The magnetic behaviour of this sample (x = 0.04) has been further investigated by La-139-NQR measurements at low temperatures (1.5 K less-than-or-equal-to T less-than-or-equal-to 12 K). Here, we observe an enhancement of the relaxation rate (1/T2) below about 7 K.