Advantageous power factor anomaly in Mn1.68-XCu0.6+X+Y+ZCo0.24-YNi0.48-zO4 thin films

Thermopower and electrical conductivity are measured on compositional variations of a reference composition, Mn_1.68-XCu_.6+X+Y+ZCo_.24-YNi_.48$ -_ZO₄, and the changes in the power factor terms are examined. Thin films obtained through Metal Organic Decomposition, MOD, are used for the compositional profiling. MOD is a low-temperature fabrication route allowing for the retention of meta-stable Mn⁴⁺ and Cu¹⁺ ions essential to these n-type materials´ properties. Conduction occurs via polaron hopping between those Mn having different oxidation states. Compositional variations modify the oxidation states of Mn and Cu, and in turn, the conductivity and thermopower values. The data indicates that replacing portions of Co with Cu raises both the conductivity and thermopower magnitude, and exchanging small amounts of Ni with Cu reduces these thermoelectric, TE, factors. Surprisingly, the effects of doping show parallel rises or declines in conductivity and thermopower magnitude.