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The rare earth (R) tri-tellurides RTe3 are model incommensurate charge density
wave compounds, and provide us with a unique opportunity to study the
electronic structure of a material deep in such a state.
The CDW gap is large, up to ~ 400 meV, so we are able to
study the coexistence between gapped and metallic parts of
the Fermi surface via several powerful and complimentary techniques.
The crystal structure of RTe3 consists of double layers of square-planar
Te sheets sandwiched between RTe blocks (shown above).
The RTe blocks do not contribute to the Fermi surface,
but the Te sheets have partially filled electronic bands
formed from Te px and py orbitals. Large regions of this simple
quasi-2D Fermi surface are nested by a single wave-vector,
incommensurate with the underlying lattice. However,
the nesting does not gap the entire Fermi surface, and
small remaining sections give rise to a metallic conductivity.
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