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https://doi.org/10.3938/NPSM.68.1302
Electrical and Magnetic Properties of Magnetite Powder during a Verwey Transition
New Phys.: Sae Mulli 2018; 68: 1302~1307
Published online December 31, 2018;  https://doi.org/10.3938/NPSM.68.1302
© 2018 New Physics: Sae Mulli.

Sunghyun YOON*

Department of Physics, Gunsan National University, Gunsan 54140, Korea
Correspondence to: shyoon@kunsan.ac.kr
Received October 2, 2018; Revised October 17, 2018; Accepted October 17, 2018.
cc This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The crystallographic, electrical and magnetic behaviors of magnetite powder in the vicinity of its Verwey transition were investigated in this study. Magnetite was prepared by synthesizing a nanoparticle precursor and then annealing it at 800 $^\circ$C for 1 h under a dynamic vacuum. Crystallographic and morphology analyses were done by using scanning electron microscope (SEM) and X-ray diffraction (XRD). The electrical and the magnetic properties were examined by using Mössbauer spectroscopy, vibrating sample magnetometer (VSM) and resistivity measurement. Both the magnetic moment and the resistivity showed discontinuous changes at the Verwey transition temperature ($T_{\rm V}$). The temperature dependence of magnetic anisotropy constant showed a monotonic decrease with increasing temperature, with slight dip near $T_{\rm V}$. Mössbauer spectra showed the superposition of two sextets, one from the tetrahedral (A) and the other from the octahedral (B) sites. The results revealed that identical charge states existed in the B site at temperatures both above and below $T_{\rm V}$. A coordination crossover resulted in a transition from an inverse to a normal spinel at or close to $T_{\rm V}$.
PACS numbers: 75.30.-m
Keywords: Magnetite, Verwey transition, Inverse spinel, Normal spinel, Coordination crossover


December 2018, 68 (12)
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