Order parameters in the Verwey phase transition
Abstract
The Verwey phase transition in magnetite is analyzed on the basis of the Landau theory. The free energy functional is expanded in a series of components belonging to the primary and secondary order parameters. A low-temperature phase with the monoclinic P2/c symmetry is a result of condensation of two order parameters X3 and 5 . The temperature dependence of the shear elastic constant C44 is derived and the mechanism of its softening is discussed.
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