Theory of Half-Metallic Double Perovskites I: Double Exchange Mechanism

Abstract

The double perovskite material \SFMO has the rare and desirable combination of a half-metallic ground state with 100% spin polarization and ferrimagnetic \Tc$\simeq 420$K, well above room temperature. In this two-part paper, we present a comprehensive theoretical study of the magnetic and electronic properties of half metallic double perovskites. In this paper we present exact diagonalization calculations of the "fast" Mo electronic degrees coupled to "slow" Fe core spin fluctuations treated by classical Monte Carlo techniques. From the temperature dependence of the spin-resolved density of states, we show that the electronic polarization at the chemical potential is proportional to magnetization as a function of temperature. We also consider the effects of disorder and show that excess Fe leaves the ground state half-metallic while anti-site disorder greatly reduces the polarization. In a companion paper titled "Theory of Half-Metallic Double Perovskites II: Effective Spin Hamiltonian and Disorder Effects", we derive an effective classical spin Hamiltonian that provides a new framework for understanding the magnetic properties of half-metallic double perovskites including the effects of disorder. Our results on the dependence of the spin polarization on temperature and disorder has important implications for spintronics.

References in corpus (13)

• Electronic Structure of Sr_2FeMoO_6
• Exotic phases induced by strong spin-orbit coupling in ordered double perovskites
• Spin-orbit coupling in $d^2$ ordered double perovskites
• Theory of Half-metallic Ferrimagnetism in Double Perovskites
• Theory of High T${}_c$ Ferrimagnetism in a Multi-orbital Mott Insulator
• Phase diagram and influence of defects in the double perovskites
• Theory of Transition Temperature of Magnetic Double Perovskites
• Theory of Half-Metallic Double Perovskites II: Effective Spin Hamiltonian and Disorder Effects
• Mean field theory for double-perovskites
• A Magnetic Model for the Ordered Double Perovskites
• Metal-insulator transition in the double perovskites
• Hidden Symmetries and their Consequences in $t_{2g}$ Cubic Perovskites
• Effective three-band model for double perovskites

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• Muon spin rotation and neutron scattering investigations of the B-site ordered double perovskite Sr2DyRuO6
• Half Metal Transition Driven by Doping Effects in Osmium Double Perovskite
• Theory of metallic double perovskites with spin orbit coupling and strong correlations; application to ferrimagnetic Ba2FeReO6
• Effects of Strain and Buffer Layer on Interfacial Magnetization in Sr${}_2$CrReO${}_6$ Films Determined by Polarized Neutron Reflectometry
• First-principles analysis of the effect of magnetic states on the oxygen vacancy formation energy in doped La${}_{0.5}$Sr${}_{0.5}$CoO${}_3$ perovskite
• Magnetic order and transport in a spin-fermion model on a superlattice