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arXiv · 1208.4853

Magnetic orders and topological phases from f-d exchange in pyrochlore iridates

Gang Chen·Michael Hermele
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Abstract

We study theoretically the effects of f-d magnetic exchange interaction in the R$_2$Ir$_2$O$_7$ pyrochlore iridates. The R$^{3+}$ f-electrons form localized magnetic doublets due to the crystal field environment, while the Ir$^{4+}$ d- electrons are more itinerant and feel a strong spin-orbit coupling. We construct and analyze a minimal model capturing this physics, treating the Ir subsystem using a Hubbard-type model. First neglecting the Hubbard interaction, we find Weyl semi-metal and Axion insulator phases induced by the f-d exchange. Next, we find that f-d exchange can cooperate with the Hubbard interaction to stabilize the Weyl semi-metal over a larger region of parameter space than when it is induced by d-electron correlations alone. Applications to experiments are discussed.

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Gang Chen, Michael Hermele. 2012-12-10. Magnetic orders and topological phases from f-d exchange in pyrochlore iridates. https://doi.org/10.1103/physrevb.86.235129

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