Understanding the Magnetic Puzzles of Double Perovskites A2FeOsO6 (A=Ca, Sr)

Abstract

Double perovskites Sr2FeOsO6 and Ca2FeOsO6 show puzzling magnetic properties, the former a low-temperature antiferromagnet while the later a high-temperature insulating ferrimagnet. Here, in order to understand the underlying mechanism, we have investigated the frustrated magnetism of A2FeOsO6 by employing density functional theory and maximally-localized Wannier functions. We find that lattice distortion enhances the antiferromagnetic nearest-neighboring Fe-O-Os interaction but weakens the antiferromagnetic interactions through the Os-O-O-Os and Fe-O-Os-O-Fe paths, which is responsible for the magnetic transition from the low-temperature antiferromagnetism to the high-temperature ferrimagnetism with the decrease of the radius of the A2+ ions. We also discuss the 5d3-3d5 superexchange and propose such superexchange is intrinsically antiferromagnetic instead of the expected ferromagnetic. Our work illustrate that the magnetic frustration can be effectively relieved by lattice distortion, which provides another dimension to tune the complex magnetism in other 3d-5d (4d) double perovskites.

18 pages, 4 figures

References in corpus (8)

• Lattice Instability and Competing Spin Structures in the Double Perovskite Insulator Sr2FeOsO6
• Ab-inito study of low temperature magnetic properties of double perovskite Sr2FeOsO6
• Synthesis, Crystal Structure and Physical Properties of Sr2FeOsO6
• Theory of Half-Metallic Double Perovskites I: Double Exchange Mechanism
• Theory of High T${}_c$ Ferrimagnetism in a Multi-orbital Mott Insulator
• Ferrimagnetism in the double perovskite Ca2FeOsO6: a density functional study
• Theory of Half-Metallic Double Perovskites II: Effective Spin Hamiltonian and Disorder Effects
• Understanding ferromagnetism in Cr-based 3d-5d double perovskites

Cited by in corpus (8)

• Competing effects at Pt/YIG interfaces: spin Hall magnetoresistance, magnon excitations and magnetic frustration
• Spin-orbit coupling controlled ground state in Sr${}_2$ScOsO${}_6$
• Origin of magnetic excitation gap in double perovskite Sr${}_2$FeOsO${}_6$
• The role of nonmagnetic d0 vs. d10 B-type cations on the magnetic exchange interactions in osmium double perovskites
• Canted ferrimagnetism and giant coercivity in the non-stoichiometric double perovskite La2Ni1.19Os0.81O6
• Room-temperature ferrimagnetism of anti-site-disordered Ca2MnOsO6
• Varying magnetism in the lattice distorted Y2NiIrO6 and La2NiIrO6
• Room temperature charge density wave in a tetragonal polymorph of Gd2Os3Si5 and study of its origin in the RE2T3X5 (RE = Rare earth, T = transition metal, X = Si, Ge) series