The effect of magnetic (phase) inhomogeneities upon the low temperature   conductivity of antiferromagnetic La_{2}CuO_{4+\delta} single crystal
  It is found that a strong inhomogeneous distribution of oxygen in single crystal La_{2}CuO_{4+\delta} can lead to the formation of isolated superconducting inclusions, the average hole concentration being no more than 0.0024 per Cu atom. The behavior of the conductivity in the magnetic field below T=20 K is consistent with possible existence of a insulating low-temperature magnetic phase (spin density waves), which is typical of cuprates with excess oxygen. 
N. V. Dalakova, B. I. Belevtsev, E. Yu. Beliayev, Yu. A.   Kolesnichenko, A. S. Panfilov, I. S. Braude