Here we report the observation of Fermi surface (FS) pockets via the Shubnikov–de Haas
effect in Na x CoO 2 for x= 0.71 and 0.84, respectively. Our observations indicate that the FS
expected for each compound intersects their corresponding Brillouin zones, as defined by
the previously reported superlattice structures, leading to small reconstructed FS pockets,
but only if a precise number of holes per unit cell is localized. For 0.71≤ x< 0.75 the
coexistence of itinerant carriers and localized S= 1/2 spins on a paramagnetic triangular …

Here we report the observation of Fermi surface (FS) pockets via the Shubnikov de Haas
effect in Na $ _x $ CoO $ _2 $ for $ x= 0.71$ and 0.84, respectively. Our observations
indicate that the FS expected for each compound intersects their corresponding Brillouin
zones, as defined by the previously reported superlattice structures, leading to small
reconstructed FS pockets, but only if a precise number of holes per unit cell is\emph
{localized}. For $0.71\leq x< 0.75$ the coexistence of itinerant carriers and localized $ S …