Abstract
We investigate novel phases that emerge from the interplay of electron correlations and strong spin-orbit interactions. We focus on describing the topological semimetal, a three-dimensional phase of a magnetic solid, and argue that it may be realized in a class of pyrochlore iridates (such as IrO) based on calculations using the method. This state is a three-dimensional analog of graphene with linearly dispersing excitations and provides a condensed-matter realization of Weyl fermions that obeys a two-component Dirac equation. It also exhibits remarkable topological properties manifested by surface states in the form of Fermi arcs, which are impossible to realize in purely two-dimensional band structures. For intermediate correlation strengths, we find this to be the ground state of the pyrochlore iridates, coexisting with noncollinear magnetic order. A narrow window of magnetic “axion” insulator may also be present. An applied magnetic field is found to induce a metallic ground state.
- Received 23 February 2011
DOI:https://doi.org/10.1103/PhysRevB.83.205101
©2011 American Physical Society
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Physical Review B 50th Anniversary Milestones
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Viewpoint
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Published 2 May 2011
Theorists predict the possibility of topological “Fermi arc” surface states in a system with broken time-reversal symmetry.
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