3D-TO-2D TRANSITION BY CS INTERCALATION OF VSE2

Angle-resolved photoemission spectroscopy has been employed to study in situ intercalation of the layered compound VSe2 with Cs. The results show that the valence band structure of VSe2, which initially is of 3D character, is transformed to become essentially 2D upon Cs intercalation. The changes, which go far beyond the rigid-band model, are successfully reproduced by self-consistent linear-augmented-plane-wave calculations. This is the first report of a UHV compatible system where the dimensionality of the electronic structure can be controlled in situ.