Above room temperature TC, 100% spin-polarization, and a high thermoelectric response in the ordered CaCu3Mn2Ir2O12

Abstract

Thermoelectric (TE), electronic, and magnetic properties of the CaCu${}_3$Mn${}_2$Ir${}_2$O₁₂ structure were studied based on ab-initio approach. Ferromagnetic and two distinct ferrimagnetic (FiM)-I/FiM-II states were examined to figure out the stable magnetic ground state of the system. Our results revealed that antiferromagnetic interactions between Cu$\uparrow$/Mn$\uparrow$ and Ir$\downarrow$ ions lead to a FiM-II. The charge transport potential for the system is assessed by estimating the various TE factors, where positive S represents the $p$-type semiconducting aspect and a high figure of merit of 0.95 at 300 K, validates the system potential for TE applications. Strikingly, the motif displays a 100% spin-polarization, holding an energy-gap of 0.7 eV in the spin-minority channel, which is high enough to restrict the spin-flipping. Further, the FiM-II ordering is verified from the calculated spin moment of 0.6/3.25/$-0.57{\mu }_B$ on the Cu/Mn/Ir ion and form spin-magnetization density isosurfaces. Finally, the estimated Curie temperature ($T_C$) is 322 K.