Influence of interstitial O on the cluster spin-glass transition of La2−xSrxCuO4+δ

The cluster spin-glass transition of La2−xSrxCuO4+δ (x=0.025 and 0.03) has been investigated by means of anelastic spectroscopy for both δ=0 and δ≈10−3. The step-like increase of the elastic energy loss coefficient due to this transition is shifted to lower temperature by excess interstitial O, thus indicating that the cluster spin-glass transition temperature depends on both Sr and O doping, similar to the Néel temperature and superconducting critical temperature. On the other hand, the intensity of the elastic energy absorption depends on the content of Sr but not on that of excess O, suggesting that the interstitial O atoms do not affect the spin texture of the cluster spin-glass state.