Magnetoelectric measurements of magnetite (Fe₃O₄) at low temperatures

Abstract

Magnetoelectric (ME) effect of magnetite (Fe₃O₄) below 35 K is discussed, mainly on the basis of the results of two experiments. One experiment shows that the magnetic field induced ME polarization along either the a axis or the b axis is reversed after reversing the electric field to the respective axes. Another experiment indicates the existence of the anomaly in the temperature dependence of ME polarizations at about 10 K. The ME polarization in both of these experiments is interpreted to be caused by the quadratic ME effect in domain structures. Through this, the following is concluded: 1) The point group of magnetite is most probably triclinic 1 below 35 K. 2) Magnetite is probably pyroelectric and ferroelectric. 3) A possible magnetic phase transition exists at about 10 K.

Key Words:

• Magnetite
• ME measurement
• point group symmetry
• domain
• ferroelectricity
• phase transition