The observation of unusual transport properties in WTe2 , such as the large non-saturating magnetoresistance with values among the highest ever reported, prompted experiments and theory to address the electronic structure of such semimetallic transition metal dichalcogenides (TMD) . WTe2 consists of layers of transition metal (TM) atoms sandwiched between two layers of chalcogen atoms, similarly to other TMDs such as MoS2 and MoSe2. Because of the layered structure, TMDs have commonly been considered as quasi-two-dimensional solids. Our previous investigation by surface sensitive ARPES, spin-resolved ARPES and DFT calculations, gave clear hints on the non-purely 2D electron states of WTe2 and suggested interlayer, i.e. k perpendicular dispersion and cross layer compensation of electrons and holes . However, in order to prove the 3D character of the bulk electronic structure, a direct inspection of the electronic properties by means of bulk sensitive technique, and more accurate calculations, was urgently needed.
By combining bulk sensitive soft-X ray angular resolved photoemission spectroscopy and accurate first principles calculations we explored the bulk electronic properties of WTe2. Despite the layered geometry suggesting a two-dimensional electronic structure, our work unambiguously finds a three-dimensional electronic dispersion. We report an evident band dispersion in the k direction perpendicular to the layers, implying that electrons can also travel coherently when crossing from one layer to the other.
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