943 research outputs found
Introduction and Fugue for String Quartet
Thesis (M.A.)--Boston University, 1949. This item was digitized by the Internet Archive
Damping of antiferromagnetic spin waves by valence fluctuations in the double layer perovskite YBaFe2O5
Inelastic neutron scattering experiments show that spin dynamics in the
charge ordered insulating ground state of the double-layer perovskite YBaFe2O5
is well described in terms of eg superexchange interactions. Above the Verwey
transition at TV = 308 K, t2g double exchange-type conduction within
antiferromagnetic FeO2--BaO--FeO2 double layers proceeds by an electron hopping
process that requires a spin flip of the five-fold coordinated Fe ions, costing
an energy 5S^2 of approximately 0.1 eV. The hopping process disrupts
near-neighbor spin correlations, leading to massive damping of zone-boundary
spin waves.Comment: RevTeX, 4 pages, 4 figures, submitted to Phys. Rev. Let
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