A DMFT study of Na$_{x}$CoO$_{2}$

Various recent experiments have roughly mapped out the phase diagram of Na$_{x}$CoO$_{2}$ (versus $x$) in an effort to understand the basic electronic structure. Interestingly, the magnetic susceptibility has been observed to be Curie-Weiss- like near NaCoO$_{2}$, and Pauli-like near CoO$_{2}$. This is counterintuitive given that NaCoO$_{2}$ is believed to be a band insulator, and CoO$_{2}$ is in the vicinity of the hydrated superconductor. LDA+DMFT calculations are presented in order to shed light on why signatures of correlations (ie. Curie-Weiss behavior) are observed near what is believed to be a band insulator (ie. NaCoO$_{2}$).