Three-dimensional electronic structure in highly doped NaxCoO2 studied by angle-resolved photoemission spectroscopy Original Research Article

We have investigated three-dimensional electronic structure for NaxCoO2 (x =0.77 and 0.65) by high-resolution angle-resolved photoemission spectroscopy to study the origin of antiferromagnetic (AF) transition of highly doped NaxCoO2(x>0.75)(x>0.75). The a 1g large hole-like Fermi surface (FS) in x =0.77 shows distinct three-dimensionality along the k z direction, and a three-dimensional small electron pocket appears around ΓΓ point, indicating strong inter-layer electronic correlation. On the other hand, x=0.65 sample does not show three-dimensional behavior. This result indicates that transition of FS as a function of band filling is closely related to the occurrence of the magnetic transition in highly doped NaxCoO2.