A magnetization study of the frustrated spinel compound Mg1.55Fe0.9Ti0.55O4

Former studies suggested a reentrant spin-glass-like behavior for the diluted spinel compound Mg1.55Fe0.9Ti0.55O4. Near equilibrium magnetization measurements in very low magnetic fields show, however, that there is no transition of any kind at any temperature. We suggest that the long-range ferrimagnetic order is destroyed by the dipolar interactions since a moderate magnetic field restores a ferrimagnetic critical behavior at 164 K. There is no evidence of a sharp spin glass or canting transition at low temperature. Short-range correlations are observed up to 300 K with a slow dynamics. High fields magnetization measurements confirm the reentrant character and give evidence of the frozen disorder or fluctuations which give rise to strong high field susceptibility.