Electronic and Magnetic Properties of double-perovskites La$_2$MnRuO$_6$ and Hole-Doped La$_2$MnFeO$_6$ and their Potential for Magnetic Refrigeration

C. Gauvin-Ndiaye; A. -M. S. Tremblay; R. Nourafkan

doi:10.1103/PhysRevB.99.125110

paper

Electronic and Magnetic Properties of double-perovskites La $_{2}$ MnRuO $_{6}$ and Hole-Doped La $_{2}$ MnFeO $_{6}$ and their Potential for Magnetic Refrigeration

arXiv:1809.07813 · doi:10.1103/PhysRevB.99.125110

Abstract

Magnetic refrigeration at room-temperature is a technology that could potentially be more environmentally-friendly, efficient and affordable than traditional refrigeration. The search for suitable materials for magnetocaloric refrigeration led to the study of double-perovskites La $_{2}$ MnNiO $_{6}$ , La $_{2}$ MnCoO $_{6}$ and La $_{2}$ MnFeO $_{6}$ . While La $_{2}$ MnNiO $_{6}$ and La $_{2}$ MnCoO $_{6}$ are ferromagnets with near room-temperature $T_{C}$ s, previous theoretical study of double-perovskite La $_{2}$ MnFeO $_{6}$ revealed that this material is a ferrimagnet due to strong electronic interactions in Fe- $d$ orbitals. Here, we investigate the double-perovskites La $_{2}$ MnRuO $_{6}$ and LaA''MnFeO $_{6}$ (A'' = Ba, Ca and Sr) with density functional theory (DFT) as materials that can counteract the effects the strong repulsion present in the in Fe- $d$ shells of La $_{2}$ MnFeO $_{6}$ and lead to a ferromagnetic state. Our study reaveals that while La $_{2}$ MnRuO $_{6}$ is also a ferrimagnet, but with a higher net magnetic moment per formula than La $_{2}$ MnFeO $_{6}$ , doubly-ordered LaA''MnFeO $_{6}$ are ferromagnets. By mapping the total energy of the LaA''MnFeO $_{6}$ compounds obtained from DFT calculations to the Ising model, we also calculate their magnetic exchange couplings. This allows us to estimate the trend in $T_{C}$ of the three doped La $_{2}$ MnFeO $_{6}$ materials with classical Monte-Carlo calculations and predict that doubly-ordered LaBaMnFeO $_{6}$ and LaSrMnFeO $_{6}$ could be suitable materials for room-temperature magnetic refrigeration.

Electronic and Magnetic Properties of double-perovskites La2​MnRuO6​ and Hole-Doped La2​MnFeO6​ and their Potential for Magnetic Refrigeration

Abstract

Electronic and Magnetic Properties of double-perovskites La $_{2}$ MnRuO $_{6}$ and Hole-Doped La $_{2}$ MnFeO $_{6}$ and their Potential for Magnetic Refrigeration