Enhanced electron correlation in rare-earth doped Ca3Co4O9

Abstract

Thermoelectric and thermodynamic properties of a series of Ca-site rare-earth R3+ doped Ca3Co4O9 were investigated. For a fixed doping level, with the reduction in R3+ radius, thermopower is found to gradually increase despite the carrier concentration remains unchanged. The scaling behavior between thermopower and electron specific heat coefficient reveals that the additional increase in thermopower originates from enhanced electron correlation which may be attributed to doping-induced chemical pressure.