AC susceptibility of a magnetite crystal

Abstract The AC susceptibility of an Fe 3 O 4 crystal has been studied from 4.2 to 300 K with field applied along a [1 1 0] direction. There is a sharp peak in χ′ and minimum in χ″ at 130 K where K 1 changes sign, a precipitous drop in χ′ and maximum in χ″ at the Verwey transition and a further, frequency-dependent decrease in χ′ accompanied by peak in χ″ below 50 K. The low-temperature behavior is associated with an activated relaxation process having τ 0 = 6 × 10 −9 s, E a = 0.04 eV which is due to the coupled electron hopping and domain wall motion.