Figure 5: Temperature dependence of residual magnetization of crystal. Values of residual magnetization were obtained from hysteresis loops of sample magnetization at different temperatures, presented in the insets: low temperatures ( K): left inset; high temperatures ( K): right inset. Sample magnetization was measured by the Hall-effect sensor. Rapid growth of irreversibility below  K confirms the fact of appearance of spatial inhomogeneity of superconducting phase distribution in a sample, which can cause additional pinning.