Electronic and Magnetic Properties of the Candidate Magnetocaloric-Material Double Perovskites La$_2$MnCoO$_6$, La$_2$MnNiO$_6$ and La$_2$MnFeO$_6$

C. Gauvin-Ndiaye; T. E. Baker; P. Karan; É. Massé; M. Balli; N. Brahiti; M. A. Eskandari; P. Fournier; A. -M. S. Tremblay; R. Nourafkan

doi:10.1103/PhysRevB.98.125132

paper

Electronic and Magnetic Properties of the Candidate Magnetocaloric-Material Double Perovskites La $_{2}$ MnCoO $_{6}$ , La $_{2}$ MnNiO $_{6}$ and La $_{2}$ MnFeO $_{6}$

arXiv:1809.07812 · doi:10.1103/PhysRevB.98.125132

Abstract

The search for room-temperature magnetocaloric materials for refrigeration has led to investigations of double perovskites. In particular, a puzzle has appeared in the La $_{2}$ MnNiO $_{6}$ , La $_{2}$ MnCoO $_{6}$ and La $_{2}$ MnFeO $_{6}$ family of compounds. They share the same crystal structure, but while La $_{2}$ MnNiO $_{6}$ and La $_{2}$ MnCoO $_{6}$ are ferromagnets below room temperature, La $_{2}$ MnFeO $_{6}$ , contrary to simple expectations, is a ferrimagnet. To solve this puzzle, we use density-functional theory calculations to investigate the electronic structure and magnetic exchange interactions of the ordered double perovskites. Our study reveals the critical role played by local electron-electron interaction in the Fe- $d$ orbital to promote the Fe $^{3 +}$ valence state with half-filled $d$ -shell over Fe $^{2 +}$ and to establish a ferrimagnetic ground state for La $_{2}$ MnFeO $_{6}$ . The importance of Hund's coupling and Jahn-Teller distortion on the Mn $^{4 +}$ ion is also pointed out. Exchange constants are extracted by comparing different magnetically ordered states. Mean-field and classical Monte-Carlo calculations on the resulting model give trends in $T_{C}$ that are in agreement with experiments on this family of materials.

arXiv commentaccepted in Physics. Rev. B

Electronic and Magnetic Properties of the Candidate Magnetocaloric-Material Double Perovskites La $_{2}$ MnCoO $_{6}$ , La $_{2}$ MnNiO $_{6}$ and La $_{2}$ MnFeO $_{6}$

Abstract

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Electronic and Magnetic Properties of the Candidate Magnetocaloric-Material Double Perovskites La2​MnCoO6​, La2​MnNiO6​ and La2​MnFeO6​

Abstract

References in corpus (3)

Cited by in corpus (5)

Electronic and Magnetic Properties of the Candidate Magnetocaloric-Material Double Perovskites La $_{2}$ MnCoO $_{6}$ , La $_{2}$ MnNiO $_{6}$ and La $_{2}$ MnFeO $_{6}$