The antisymmetric double exchange spin state

Abstract

A reconsideration of the lowest antisymmetric spin state in the Anderson-Hasegawa double exchange (DE) model removes several complications which are manifest in the understanding of DE manganite systems. The new approach (1) describes the antiferromagnetic insulating charge ordered state as an excited state of the symmetric DE metallic ferromagnetic state. (2) Mends the discrepancies in the deGennes and Anderson-Hasegawa DE descriptions and can be readily modified to incorporate polaron and Jahn-Teller effects. (3) Reduces the DE binding energy, so that level crossings between symmetric and antisymmetric states become more likely. (4) Asks for a second (orientational) quantization in addition to the standard k-quantization in the case of DE magnetic lattices. (5) Opens a new way of calculating spin-dependent bandstructures simultaneously with the local spin structure. (6) Allows a straightforward interpretation of many so-called peculiar and puzzling experimental results such as sequences of giant positive/negative magnetoresistances, electroresistive effects, giant magnetoabsorption etc. (c) 2007 Elsevier B.V. All rights reserved.