Verwey transition

The Verwey transition is a low-temperature phase transition in the mineral magnetite associated with changes in its magnetic, electrical, and thermal properties.^[1] It typically occurs near a temperature of 120 K but is observed at a range of temperatures between 80 and 125 K, although the spread is generally tight around 118–120 K in natural magnetites.^[1][2] Upon warming through the Verwey transition temperature (T_V), the magnetite crystal lattice changes from a monoclinic structure insulator to the metallic cubic inverse spinel structure that persists at room temperature.^[3] The phenomenon is named after Evert Verwey, a Dutch chemist who first recognized, in the 1940s, the connection between the structural transition and the changes in the physical properties of magnetite. This was the first metal-insulator transition to be found.^[4]

The Verwey transition is near in temperature, but distinct from, a magnetic isotropic point in magnetite, at which the first magnetocrystalline anisotropy constant changes sign from positive to negative.^[5]

The temperature and physical expression of the Verwey transition are highly sensitive to the stress state of magnetite and the stoichiometry. Non-stoichiometry in the form of metal cation substitution or partial oxidation can lower the transition temperature or suppress it entirely.^[5][6]

See also

• Morin transition – Magnetic phase transition in α-Fe₂O₃ hematite