Journal
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS
Volume 177, Issue 16, Pages 1514-1517Publisher
ELSEVIER
DOI: 10.1016/j.mseb.2012.03.041
Keywords
Double perovskites; Density functional theory; Small clusters; Bulk material; Half-metallic ferromagnetism
Funding
- UNAM [SIP-IPN: 2012-1439, PAPIIT-IN108710]
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To understand the differences in behaviour between up- and down-spin electrons observed in the half-metallic Sr2FeMoO6 double perovskite, the density of states (DOS) was studied for the (FeO6)(-4) and (MoO6)(-6) octahedral clusters using first-principles density functional theory within the generalised gradient approximation (GGA) scheme and the Perdew-Burke-Ernzerhof (PBE) functional. Our results reveal that half-metallic character is present, even starting from an isolated (FeO6)(-4) cluster, and is a consequence of spin decoupling of antibonding hybridisations between iron t(2g) states and oxygen p states (t(2g)(a) states). i.e., t(2g)(a) states lie below the Highest Occupied Molecular Orbital (HOMO) in the up-spin channel, whereas they lie above the HOMO level in the clown-spin channel. The spin-induced shifting between up-spin and down-spin DOS situates the HOMO in such a way that the molecular orbitals oxygen p states (p bands) are fully spin-paired by octet electrons. Thus, the down-spin channel has metallic character because the HOMO lies just at the p bands, and the up-spin channel is semiconducting because the HOMO falls within the energy gap between the t(2g)(a) and e(g)(a) bands. Finally, the (MoO6)(-6) octahedron does not inhibit the perovskite half-metallic character since this cluster has a zero total spin. (C) 2012 Elsevier B.V. All rights reserved.
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