Exploring the effect of strong electronic correlations in Seebeck Coefficient of the NdCoO3 compound : Using experimental and DFT+U approach

Abstract The presence of complexity in the electronic structure of strongly correlated electron system NdCoO 3 (NCO) have sparked interest in the investigation of its physical properties. Here, we study the Seebeck coefficient ( α ) of NCO by using the combined experimental and DFT+ U based methods. The experimentally measured Seebeck coefficient is found to be ∼444 μ V / K at 300 K, which decreases to 109.8 μ V / K at 600 K. In order to understand the measured Seebeck coefficient, we have calculated the PDOS and band structure of the NCO. Furthermore, the calculated occupancy of 6.4 for Co 3 d orbitals and presence of large unoccupied O 2 p states indicate the covalent nature of the bonding. Apart from this, the maximum effective mass is found to be 36.75 (28.13) m e for the spin-up (dn) channel in conduction band indicates the n-type behaviour of the compound in contrast to our experimentally observed p-type behaviour. While, the calculated Seebeck coefficient at the temperature-dependent chemical potential ( μ ) at 300 K shows the p-type behaviour of the compound. Fairly good agreement is seen between the calculated and measured values of α at U ff = 5.5 eV and U dd = 2.7 eV. The maximum power factor (PF) is found to be 47.6 (114.4)×10 14 μW K −2 cm −1 s −1 at 1100 K, which corresponds to p (n)-type doping of ∼1.4 (0.7)×10 21 cm −3 . This study suggests the importance of strong on-site electron correlation in understanding the thermoelectric property of the compound