Charge transfer near the Néel temperature in La$_{\mathbf{2}}$CuO$_{\mathbf{4+x}}$

The electrical resistance and the thermoelectric power in the $ab$ plane of a weakly oxygen-doped La$_2$CuO$_{4+x}$ crystal $(0.001<x<0.007)$ and its static magnetic susceptibility were studied in the vicinity of antiferromagnetic transition. The electrical resistance and the thermoelectric power behave anomalously near the Néel temperature, indicating that the transport is strongly affected by the establishment of long-range antiferromagnetic order. Analysis of the obtained data allows the conclusion to be drawn that the doping gives rise to a conduction band as a result of the overlap between the wave functions of deep impurity states that are strongly renormalized due to the correlation and polaron effects.