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SS22 WS22 SS23 WS23 SS24 WS24 Guidelines for Master Students
Electronic, magnetic, and optical properties of manganese pnictides Strong electronic correlations happen very often in open d- or f- shells close to half filling. As an example of such systems we study BaMn2As2 and LaOMnAs, two manganese pnictides. They are similar to the extensively studied iron pnictide high-temperature supercondductors BaFe2As2 and LaOFeAs, but with the difference of having only 5 electrons in the d shell as compared to 6 electrons in the iron systems. This has important consequences, in the sense that electronic interactions are much stronger. As a result, we show that both materials are close to a Mott metal-to-insulator transition. This location in the phase diagram leads to strong magnetism, with a remarkably high Neel temperature of 625K for BaMn2As2. We also discuss the difference in the magnetic ordering temperatures and trace it back to the different dimensionality oft he electronic structure in these compounds. Finally, we also study the optical conductivity. The inclusion of correlation effects gives optical spectra in very good agreement, which cannot be achieved by density-functional theory calculations alone. |