Coulomb Correlations and Electronic Structure of CuCo2S4: a DFT + DMFT Study

By employing a combined method of density functional theory and dynamical mean-field theory (DFT + DMFT) we study the spectral properties and local moment formation in the normal state of a Cobased superconductor CuCo2S4. The obtained quasiparticle mass enhancement m*/m similar to 1.2 is smaller than that in iron-based parent compounds indicating weak correlations in the Co 3d states. We show that the mass enhancement is accompanied by an insignificant renormalization and shift of the bands in the vicinity of the Fermi level. This subtle modification is sufficient to induce a substantial transformation of one of the Fermi surface sheets and occurs due to the presence of shallow Fermi surface pockets in the electronic structure of CuCo2S4. The calculated local and fluctuating moments are smaller than those in iron-based superconductors questioning the importance of spin fluctuations for understanding the pairing mechanism of CuCo2S4.