Re-entrant spin freezing behavior in La0.85Ca0.15Mn0.95Fe0.05O3 manganite

The effects of partially replacing Mn with Fe ions in the La0.85Ca0.15MnO3 system are reported. On replacing 5% of the Mn with Fe ions the system exhibits a transition to a re-entrant spin glass like phase with a ferromagnetic transition at 170K and spin freezing transition at T similar to 100K. The system remains insulating throughout both the ferromagnetic and glassy phases with however a sharp resistivity increase at low temperature (T similar to 150K). The spin freezing temperature shifts upwards with increasing frequency and magnetic relaxation effects are observed. However conventional spin glass features such as a memory effect are not observed and the spin freezing temperature is relatively insensitive to applied magnetic fields. (C) 2003 Published by Elsevier B.V.