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Spin state and phase competition in TbBaCo_{2}O_{5.5} and the lanthanide series LnBaCo_{2}O_{5+δ} (0<=δ<=1)

Hua Wu
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Abstract

A clear physics picture of TbBaCo$_{2}$O$_{5.5}$ is revealed on the basis of density functional theory calculations. An antiferromagnetic (AFM) superexchange coupling between the almost high-spin Co$^{3+}$ ions competes with a ferromagnetic (FM) interaction mediated by both p-d exchange and double exchange, being responsible for the observed AFM-FM transition. And the metal-insulator transition is accompanied by an xy/xz orbital-ordering transition. Moreover, this picture can be generalized to the whole lanthanide series, and it is predicted that a few room-temperature magnetoresistance materials could be found in LnBa$_{1-x}$A$_{x}$Co$_{2}$O$_{5+δ}$ (Ln=Ho,Er,Tm,Yb,Lu; A=Sr,Ca,Mg).

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Hua Wu. 2001-06-20. Spin state and phase competition in TbBaCo_{2}O_{5.5} and the lanthanide series LnBaCo_{2}O_{5+δ} (0<=δ<=1). https://doi.org/10.1103/physrevb.64.092413

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