Aspects of the Verwey transition in magnetite

Article

关键词: LOW-TEMPERATURE PHASE;    ORGANIC CONDUCTORS;    ELECTRONIC-PROPERTIES;    DIFFUSE-SCATTERING;    SINGLE-CRYSTAL;    FE3O4;    INTERPLAY;    NMR;   

DOI  :  10.1103/PhysRevB.65.085107

来源: SCIE

【 摘 要 】

A mechanism of the Verway transition in magnetite (Fe3O4), which has been argued to be a charge ordering transition so far, is proposed. Based on mean-field calculations for a three-band model of spinless fermions appropriate for d electrons of Fe ions in B sites, it is indicated that the phase transition should be a bond dimerization due to the cooperative effects of strong electronic correlation and electron-phonon interaction. The results show that the ferro-orbital ordered state is stabilized in a wide temperature range due to the strong on-site Coulomb interaction between different t(2g) orbitals, resulting in an effectively one-dimensional electronic state, which leads the system toward an insulating state through a Peierls lattice distortion with a period of two Fe(B) ions, i.e., bond dimerization. Furthermore, it is found that the interplay between such lattice distortions in Fe(B) ions, and the lattice elastic energy of Fe(B) -O as well as Fe(A)-O bonds, gives rise to a competition between two different three-dimensional patterns for the bond dimerization, and can stabilize a complicated one with a large unit-cell size. The results are compared with the known experimental facts.

【 授权许可】

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