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HISTORY Although the band theory of solids had been very successful in describing various electrical properties of materials, in 1937 Jan Hendrik De Boer and Evert Johannes Willem Verwey pointed out that a variety of Transition Metal Oxide s that were predicted to be conductors by band theory were in fact insulators[1]. Nevill Mott and R. Peierls then predicted that this anomaly could be explained by including interactions between electrons[2]. In 1949, in particular, Mott proposed a model for NiO as an insulator, in which conduction could be understood by the formula {Link without Title} : :(Ni2+O2-)2 Ni3+O2- + Ni1+O2- In this situation, the formation of an energy gap preventing conduction can be understood as the competition between the Coulomb Potential U between 3d electrons, and the transfer integral t of 3d electrons between neighbouring atoms (the transfer integral is a part of the tight-binding approximation). The total Energy Gap is then: :Egap = U - 2zt where z is the number of nearest neighbour atoms. In general, Mott insulators occur when the repulsive Coulomb potential U is large enough to create an energy gap. One of the simplest theories of Mott insulators is the Hubbard Model . APPLICATIONS Mott insulators are of growing interest in advanced Physics research, and are not yet fully understood. They have applications in Thin-film Magnetic Heterostructure s and High-temperature Superconductivity . {Link without Title} SEE ALSO REFERENCES {Link without Title} J H de Boer and E J W Verwey, Proceedings of the Physical Society of London 49, 59 (1937). {Link without Title} N F Mott and R Peierls, Proceedings of the Physical Society of London 49, 72 (1937). {Link without Title} N F Mott, Proceedings of the Physical Society of London Series A 62, 416 (1949). {Link without Title} Simon Foelling, Artur Widera, Torben Mueller, Fabrice Gerbier, Immanuel Bloch, "Formation of spatial shell structures in the superfluid to Mott insulator transition," http://arxiv.org/PS_cache/cond-mat/pdf/0606/0606592v1.pdf. |
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