Dielectric Properties of Fe₃O₄ Single Crystal at Low Temperatures

Abstract

Temperature dependence of the dielectric constant and the ac conductivity of Fe₃O₄ single crystal has been studied below the Verwey point of 122 K in a frequency range from 10 Hz to 10 kHz. Dielectric relaxation phenomena have been found in two temperature ranges: one appears around 30 K–50 K and the other occurs below 20 K. The former has frequency dependence of ac conductivity described by the relation, σ_ac∝ω^s (s≤1); the latter is accompanied with the formation of a space-charge layer. Some discussions about the origin of the dielectric relaxation are given.