Tungsten telluride is a semi-metallic material, which is a gray solid under normal temperature and pressure. It is non-magnetic. Its CAS number is 12067-76-4; Molecular formula is WTe2; Molecular weight is 441.05600; Accurate mass is 445.77900; Density is 9.43g/cm3; Melting point is 1020°C.
Recently, WTe2 is predicted to be a Weyl semimetal and, in particular, to be the first example of a "Type II" Weyl semimetal, where the Weyl nodes exist at the intersection of the electron and hole pockets.
The structure of tungsten ditelluride is layered, and the substance can be exfoliated into thin sheets down to monolayers. However, electrons can easily move between the layers, unlike in other two dimensional semiconductors.
Tungsten ditelluride was discovered to exhibit an extremely large magnetoresistance in October 2014: 13 million percent with no known saturation point. The resistance is proportional to the square of the magnetic field. This may be due to the material being the first example of a compensated semimetal, in which the number of mobile holes is the same as the number of electrons. The fraction of charge carriers is 0.005 per formula unit (WTe2).
When subjected to pressure, the magnetoresistance effect in WTe2 is reduced. At a pressure of 10.5GPa magnetoresistance disappears. Above this same pressure of 10.5GPa tungsten ditelluride can become a superconducter. At 13.0GPa the transition to superconductivity happens below 6.5K.
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