Verwey transition

The Verwey transition is a low-temperature phase transition in the mineral magnetite near 125 kelvins associated with changes in its magnetic, electrical, and thermal properties.[1] Upon warming through the Verwey transition temperature (TV), the magnetite crystal lattice changes from a monoclinic structure to the cubic inverse spinel structure that persists at room temperature.[2] The phenomenon is named after Evert Verwey, a Dutch chemist who first recognized the connection between the structural transition and the changes in the physical properties of magnetite.

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. 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.[3][4]

References

  1. ↑ Walz, Friedrich (15 March 2002). "The Verwey transition - a topical review". Journal of Physics: Condensed Matter. 14 (12): R285&ndash, R340.
  2. ↑ Kosterov, Andrei (2007). "Magnetic properties, low‐temperature". In Gubbins, David; Herrero-Bervera, Emilio. Encyclopedia of geomagnetism and paleomagnetism. Dordrecht: Springer. pp. 515&ndash, 525. ISBN 9781402044236.
  3. ↑ Aragón, Ricardo; Buttrey, Douglas J.; Shepherd, John P.; Honig, Jurgen M. (1 January 1985). "Influence of nonstoichiometry on the Verwey transition". Physical Review B. 31 (1): 430–436. Bibcode:1985PhRvB..31..430A. doi:10.1103/PhysRevB.31.430.
  4. ↑ Özdemir, Özden; Dunlop, David J.; Moskowitz, Bruce M. (20 August 1993). "The effect of oxidation on the Verwey transition in magnetite". Geophysical Research Letters. 20 (16): 1671–1674. Bibcode:1993GeoRL..20.1671O. doi:10.1029/93GL01483.
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