MAGNETIC AFTEREFFECTS IN ZINC FERRITES

Magnetic after-effect (MAE) spectra on differently sintered zinc ferri tes, ZnxFe3-x-DeltaO4 with 0.1 less than or equal to x less than or eq ual to 0.5 containing orthogonal vacancies (10(-5) < Delta < 10(-3)) a re investigated in the temperature range 4 K < T < 450 K: using an LC- oscillator technique. The low-temperature MAE processes due to electro n tunnelling (4 K < T < 35 K) and hopping (50 K T < 125 K) are severel y affected and tile Verwey; transition is completely suppressed for th e given range of Zn substitutions. Around 300 K, the vacancy-induced p eak III appears, being accompanied by a Zn-induced high-temperature sa tellite (T greater than or equal to 380 K), known as process II. The v acancy-mediated relaxation model of process III is modified so as to e xplain the role of substituted Zn2+ on tile observed MAE spectra.