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Infrared and Raman Studies of 1T-TiTe2.
Lev Gasparov, Department of Chemistry and Physics, University of North Florida
Magnetite (Fe3O4) is a naturally occurring mineral interesting for remarkably
different fields of science. It is the first magnetic material known to mankind
and it is the earliest compound known to manifest charge-ordering transition
discovered by Verwey in 1939. At the same time magnetite is an integral part
of many live objects such as magnetotactic bacteria. Furthermore, it was
reported that magnetite occurs in human brains and it may play a role in
pathogenesis of the neurodegenerative diseases such as Alzheimer.
Magnetite (Fe3O4) is an example of the Correlated Electron Materials. These
materials represent an intermediate case of the electronic structure of solids
between those that have itinerant electrons and those with localized
electrons. Even though magnetite has been extensively studied for more
than sixty years the physics of this compound is not completely understood.
In particular, one of the main puzzles of magnetite is the nature of the Verwey
transition.
In this project the PI used Raman scattering to study magnetite. Raman
spectra of optimally doped magnetite (Fe3O4) single crystals reveal broad
electronic background extending up to 900 wavenumbers (~110 meV).
Redistribution of this background is observed when sample is cooled below
the Verwey transition temperature (TV= 123K). Such redistribution may be
assigned to an opening of the charge gap at about 350 wavenumbers (43
meV). The value of the gap is within the range of the photoemission data on
freshly fractured magnetite sample.
J. Appl. Phys. 101, 09G108-1 (2007)