Canonical magnetic insulators with isotropic magnetoelectric coupling

Abstract

We have performed an exhaustive representation-theory-based search for the simplest structures allowing isotropic magnetoelectric coupling. We find 30 such structures, all sharing a common pattern of atomic displacements in the direction of atomic magnetic moments. We focus on one of these 30 canonical structures and find that it is generically realized in a class of fractionally substituted pyrochlore compounds with an all-in-all-out magnetic order. Furthermore, we find that these substituted pyrochlore compounds have a substantial Chern-Simons orbital magnetoelectric component (θ=0.1--0.2). While this component is also formally present in strong Z_2 topological insulators (θ=π), its effects are observable there only if time-reversal symmetry is broken at the surface.

5 pages with 2 figures. Supplementary information: http://civet.berkeley.edu/~sinisa/pubs/supp/canon_supp.pdf

References in corpus (3)

• Topological Field Theory of Time-Reversal Invariant Insulators
• Tetrahedral Magnetic Order and the Metal-Insulator Transition in the Pyrochlore Lattice of Cd2Os2O7
• Full magnetoelectric response of Cr2O3 from first principles

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