  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.

Superconductivity;Strongly Correlated Electrons