MAGNETIC AFTEREFFECTS IN TITANIUM FERRITES

Magnetic aftereffect (MAE) measurements in TixFe3-x-DeltaO4 with 0.01 less than or equal to x less than or equal to 0.4 (Delta approximate t o 10(-4)) are performed by means of an oscillator technique in the tem perature range 4 K < T < 460 K. The specific electronic MAE processes below the Verwey temperature, i.e., tunnelling (4 K < T < 35 K) and lo ng-range hopping (50 K < T < 125 K), are found to be severely affected in the presence of even small Ti contents (0.01 less than or similar to x less than or equal to 0.1). Above the Verwey temperature four mai n processes are detected around 215 K (IV'), 260 K (IV), 300 K (III) a nd 415 K (II). Atomistic models, based on the vacancy model for proces s III in magnetite, are proposed in order to explain the observed spec tra.