Evaluation of the electronic, optical, thermoelectrical and magnetic properties of manganite perovskites via DFT calculations and critical exponent analysis

Abstract

Samples of La_0.8Sr_0.2Mn_0.8Co_0.2O₃ were synthesized using the sol–gel method at different gelation temperatures to study their electronic, optical, thermoelectric and magnetic properties. Electronic structure calculations for the spin-down configuration reveal a p-type semiconducting behaviour with an indirect band gap of 3.44 eV, while the spin-up configuration exhibited metallic behaviour. Density of states analysis shows a clear spin asymmetry and significant Mn–Co–O hybridization near the Fermi level. The optical results present a high static dielectric constant and strong ultraviolet absorption below 300 nm, with a derived band gap of 3.44 eV, consistent with band structure analysis. The power factor increased steadily with temperature, suggesting suitability for thermoelectric use at high temperatures. Magnetic characterization using modified Arrott plots, Kouvel–Fisher analysis and scaling hypothesis enables determination of the critical exponent, suggesting short-range ferromagnetic interactions or mixed-range magnetic ordering depending on the gelation temperature.