  Thermodynamic properties of cubic Heisenberg ferromagnets with competing
exchange interactions are considered near the frustration point where the
coefficient $D$ in the spin-wave spectrum $E_{\mathbf{k}}\sim D k^{2}$
vanishes. Within the Dyson-Maleev formalism it is found that at low
temperatures thermal fluctuations stabilize ferromagnetism by increasing the
value of $D$. For not too strong frustration this leads to an unusual "concave"
shape of the temperature dependence of magnetization, which is in agreement
with experimental data on the europium chalcogenides. Anomalous temperature
behavior of magnetization is confirmed by Monte Carlo simulation. Strong field
dependence of magnetization (paraprocess) at finite temperature is found near
the frustration point.
