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

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.

7 pages, 5 figures. Paper has been slightly restructured, and new refs have been added

References in corpus (3)

• Topological Field Theory of Time-Reversal Invariant Insulators
• Three dimensional topological invariants for time reversal invariant Hamiltonians and the three dimensional quantum spin Hall effect
• Magnetic Order and Charge Disproportionation in a Spin-ice type Kondo Lattice Model: Large Scale Monte Carlo Study

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