Exchange interactions in hexagonal YMnO3 and LuMnO3 multiferroic compounds

Abstract

Abstract In this work, spin density functional theory calculations are employed to obtain the exchange interactions in hexagonal YMnO3 and LuMnO3 multiferroic compounds, which have been a matter of debate in the literature. The exchange and correlation electronic effects are approximated using the local spin density approximation (LSDA) with the inclusion of the effective Hubbard U correction (Ueff). The intraplane superexchange interaction (Jnn) decreases with increasing Ueff. Moreover, the Jnn value with the best agreement with experiment is found for Ueff values between 2.55 and 4.0\xa0\u200beV. Without the addition of Ueff corrections, i.e., with standard LSDA calculations, the magnitude of Jnn is overestimated. The Bader topological analysis of the electron density at the bond critical point shows that the closed-shell interaction of the Mn–O3 and Mn–O4 bonds in both materials increases with increasing Ueff, which justifies the decrease of Jnn with increasing Ueff.. Additionally, both interplane and intraplane super-superexchange interactions are computed and compared with previous studies.