  The magnetic susceptibility of the two-dimensional repulsive Hubbard model
with nearest-neighbor hopping is investigated using the diagram technique
developed for the case of strong correlations. In this technique a power series
in the hopping constant is used. At half-filling the calculated zero-frequency
susceptibility and the square of the site spin reproduce adequately results of
Monte Carlo simulations. Also in agreement with numerical simulations no
evidence of ferromagnetic correlations was found in the considered range of
electron concentrations $0.8\alt\bar{n}\alt 1.2$ for the repulsion parameters
$8|t|\leq U\leq 16|t|$. However, for larger $U/|t|$ and $|1-\bar{n}|\approx
0.2$ the nearest neighbor correlations become ferromagnetic. For $\bar{n}\alt
0.94$ and $\bar{n}\agt 1.06$ the imaginary part of the real-frequency
susceptibility becomes incommensurate for small frequencies. The
incommensurability parameter grows with departure from half-filling and
decreases with increasing the frequency. This behavior of the susceptibility
can explain the observed low-frequency incommensurate response observed in
normal-state lanthanum cuprates.
