Electronic Structure Basis for the Extraordinary Magnetoresistance in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>WTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

The electronic structure basis of the extremely large magnetoresistance in layered nonmagnetic tungsten ditelluride has been investigated by angle-resolved photoelectron spectroscopy. Hole and electron pockets of approximately the same size were found at low temperatures, suggesting that carrier compensation should be considered the primary source of the effect. The material exhibits a highly anisotropic Fermi surface from which the pronounced anisotropy of the magnetoresistance follows. A change in the Fermi surface with temperature was found and a high-density-of-states band that may take over conduction at higher temperatures and cause the observed turn-on behavior of the magnetoresistance in WTe2 was identified.