Eur. Phys. J. B 43, 201-212 (2005)
https://doi.org/10.1140/epjb/e2005-00043-5

Magnetic AC susceptibility of stoichiometric and low zinc doped magnetite single crystals

¹ Institute of Nuclear Physics, Kraków, Poland
² Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Kraków, Poland
³ Department of Chemistry, Pukyong National University, Pusan 608-737, Korea
⁴ Department of Geology and Geophysics, University of Wisconsin-Madison, USA
⁵ Department of Chemistry, Purdue University, West Lafayette, Indiana, USA

Corresponding author: ^a kakol@uci.agh.edu.pl

Received: 25 September 2004
Published online: 25 February 2005

Abstract

Systematic studies of AC susceptibility in a stoichiometric magnetite single crystal, in a series of low zinc doped magnetite () and in nonstoichiometric magnetite samples (both single crystals and pellets) in the temperature range 4–300 K are presented. Measurements were performed in several AC fields (Oe) and at different frequencies (15–6000 Hz). It is suggested that the signal is primarily due to magnetic domain wall movement, strongly influenced by structural domains (twins). Two sets of anomalies were found: the first is associated with the Verwey transition and the second involves two different effects, one at 28 K, observed only in stoichiometric magnetite, and the other at 50 K. While the temperature position of the first anomaly (28 K) does not depend on frequency, the effect at 50 K is associated with an activation process, shifting to higher temperatures with increasing frequency. This last effect may be linked to the low temperature magnetoelectric effects terminating approximately at those temperatures. Qualitatively similar results have been observed by the Magnetic After Effect technique presented in the literature, that is associated with relaxation times that are 10⁴ higher than those characteristic of our technique.