Semiconductor to half-metal transition in magnetic Ce cation incorporated A-site-ordered quadruple perovskite CeMn3Mn4O12

Abstract

The charge degree of freedom of A-site cation as well as B-site cation plays a significant role in determining the internal charge distribution and gives rise to fascinating physical properties in perovskite oxides. Here, we discuss the magnetic couplings and electronic structures of rare-earth Ce cation incorporated A-site-ordered quadruple perovskite CeMn3Mn4O12 via first-principles calculations. This report demonstrates that the A site Ce is magnetic cation with quantity of 4 f electrons, which is quite different from the nonmagnetic Ce4+ usually found in isostructural compounds. As a result, not only the A′ and B site manganese sublattices but also the A site cerium sublattice is involved in the complex magnetic interactions. In the low-temperature phase, CeMn3Mn4O12 is ferrimagnetic with the Ce(↓)-Mn1(↑)-Mn2(↓)-Mn3(↑)-Mn4(↑)-Mn5(↓) type, in which the effective magnetic couplings are generated from A-site Ce sublattice as well as the antiparallel arrangement within both the A and B site manganese sublattices. The analysis of electronic structure reveals the valence distribution is Ce3+Mn3+3Mn3+4O2-12 where both the oxidation state of Ce and Mn is +3. Nevertheless, ferromagnet is the most favorable in energy with a large saturated magnetic moment at the high-temperature phase. Interestingly, the electronic structure undergoes a semiconducting to half-metallic transition accompanying with the phase transformation. The present results offer a new strategy to realizing the tunable charge distribution via variable valence A site cation in A-site-ordered quadruple perovskites and thus open an avenue to modulate these materials with exotic properties.